Head CFM vs. HP per c.i.?

[Nastytls]

Is there a standard of how much HP you should be able to achieve given the amount of CFM your heads flow? Meaning, if your head flows 300CFM you can achieve (x) hp ci.

[Ohio HD]

It's all dependent on everything else being maximized and optimum as well.


http://www.wallaceracing.com/calcafhp.php

[kd]

   What he said. I think it's better to think in terms of what it will "support" and not what it will "produce" because the other components team up to help the "produce" part.

[Don D]

Assuming what a hurricane head that flows 372 @.7 lift 28" at 124" VS a CVO head that flows 330 similar conditions, all parts being the same and assuming a proper tune will the bigger heads make 12+% more power?

[No Cents]

   too many unknown variables to give a positive answer to the OP's question. Calculators can put you in the ball park...but they are not an exact science.
   Unless you can find the same exact combo you are questioning...the answer would be to dyno the combination you have in question to see what the results will show you. Changing one simple part in a combo can change the outcome you will see on a dyno.
   A good set of flowing heads won't do crap for you if you don't have the other needed accompanying parts to go with it. A good induction system with a good exhaust are critical to make a good set of flowing heads work up to their potential.

[Hossamania]

It also depends on who is making them flow 300 cfm. I bet with a little practice, I could get 300 cfm flow numbers.
But I'm pretty sure they are not going to work very well, no matter what combination of parts you use!

[Nastytls]

  What he said. I think it's better to think in terms of what it will "support" and not what it will "produce" because the other components team up to help the "produce" part.

OK, so I think you have verbalized it better than I did. The above posted calculator kind of does what I was thinking. According to it, 300cfm will support approximately 1.2HP per ci. in a 2 cylinder engine.
What made me think of the question was the amount of CFM the 4valves are flowing vs. the power they seem to be producing. The twin cam heads that are flowing these large numbers are generally the real high HP builds

[K4FXD]

Velocity is important. The 370 head will support more HP but it might only make power starting at 5000 RPM. The 320 CFM head will make less HP but might start making power at 2000 RPM.

That is a very generalized description cause I'm sure a Head Porter will chime in and tell us his 370 CFM heads make good velocity starting at 1500.

[Matt C]

Velocity is a function of the port's cross sectional area (CSA), the displacement of the cylinder
it's feeding and the targeted RPM range.

That formula only tells you how much air you have to move to achieve a certain HP. It doesn't
take into account weather you move it through a 2" opening or a 2' opening. Moving the right
amount of air through the correct CSA is the key.

[Matt C]

Additionally, if the engine for example, demands 250 CFM, putting a head on it that delivers
350 CFM, will likely hurt performance b/c the CSA will be too big to maintain a high enough
velocity through the runner.

The engine will theoretically be able to deliver more HP with the bigger head, but it would likely
be an RPM that would not be attainable or one that would destroy the engine. And it wouldn't have any TQ
until the velocity got up to around 250-350 ft/s.

[1FSTRK]

Is there a standard of how much HP you should be able to achieve given the amount of CFM your heads flow? Meaning, if your head flows 300CFM you can achieve (x) hp ci.

It is a yes and no answer. This is why large data samples are so important, the best number you can find for an engine family is the standard at the time. This is one reason I have posted so much on the M-8 engines not living up to their potential.

The ratio of air to hp gives you an indicator of the over all efficiency of that engine so when the CFM of the heads is to high in relation to the hp it tells you something is wrong in the combination, the hard part for most people is it does not tell you what is wrong.

[Deye76]

"Velocity is important. The 370 head will support more HP but it might only make power starting at 5000 RPM."

Guy I know has Hurricane heads on a 120" @ 12.4:1 cr, says it's a PIA to ride under 3500 rpm. He is rapidly learning that bigger isn't always better.

[rigidthumper]

I had a local put MVA heads on his 103 with 999 cams and wonder why it was a slug!

[Don D]

  What he said. I think it's better to think in terms of what it will "support" and not what it will "produce" because the other components team up to help the "produce" part.

OK, so I think you have verbalized it better than I did. The above posted calculator kind of does what I was thinking. According to it, 300cfm will support approximately 1.2HP per ci. in a 2 cylinder engine.
What made me think of the question was the amount of CFM the 4valves are flowing vs. the power they seem to be producing. The twin cam heads that are flowing these large numbers are generally the real high HP builds

How do you know 300 cfm will support 1.2? That engine, the air pump, may be 88" or 131" for example.  It has so much demand at the VE and peak rpm dictated by the rest of the system forming both individual and a system constraint.
Velocity can be your friend or enemy. Too much and there are pumping losses and a very hard to tune motor. Too slow and the ports are too big to feed the pump, result reversion low VEs, and high brake specific fuel consumption. All total a very inefficient engine. A larger slower port is more easily dealt with especially with an efi fed engine.  Harley just did this clad in emissions legal trim. It's called the m8.
Oh by the way what about the exhaust side? Some of the best of harley offerings have an awful handling of the waste, just saying.

[Nastytls]

  What he said. I think it's better to think in terms of what it will "support" and not what it will "produce" because the other components team up to help the "produce" part.

OK, so I think you have verbalized it better than I did. The above posted calculator kind of does what I was thinking. According to it, 300cfm will support approximately 1.2HP per ci. in a 2 cylinder engine.
What made me think of the question was the amount of CFM the 4valves are flowing vs. the power they seem to be producing. The twin cam heads that are flowing these large numbers are generally the real high HP builds

How do you know 300 cfm will support 1.2? That engine, the air pump, may be 88" or 131" for example.  It has so much demand at the VE and peak rpm dictated by the rest of the system forming both individual and a system constraint.
Velocity can be your friend or enemy. Too much and there are pumping losses and a very hard to tune motor. Too slow and the ports are too big to feed the pump, result reversion low VEs, and high brake specific fuel consumption. All total a very inefficient engine. A larger slower port is more easily dealt with especially with an efi fed engine.  Harley just did this clad in emissions legal trim. It's called the m8.
Oh by the way what about the exhaust side? Some of the best of harley offerings have an awful handling of the waste, just saying.

"I" don't know, I said according to the posted calculator that's what it will do.

[Don D]

OK my point is CFM/hp at 2 cylinders is not enough information to come to any decision. Bore, stroke, VE all are important data needed. This is where the software calculators such as dynomation come in and do a good job of helping calculate the engines demands when the user has some real world experience to temper the results. Also the software included in the flow bench programs helps calculate velocity based on CSA. Or you can calculate that long hand.
If this is of interest I suggest a book
Engine Airflow, A Practical Guide to Airflow Theory, by Harold Bettes ISBN-10: 1557885370

[Thermodyne]

Head flow can be used to calculate volumetric efficiency.  That's one of the numbers you'll need to plug into any good HP calculator. 

VE =  3456 x CFM / CID x RPM

[Don D]

Well not exactly
That calculation would be how much the air pump moves at 100% VE
Problem is VE is a factor and varies according to the efficiency of the whole system. An average Harley is not running that high, 100%. A well healed LS chevy new story, a F1 better yet

[prodrag1320]

Having a build with parts that compliment each other,with the proper compression & quality headflow is way more important than CFM amount

[1FSTRK]

Head flow can be used to calculate volumetric efficiency.  That's one of the numbers you'll need to plug into any good HP calculator. 

VE =  3456 x CFM / CID x RPM

I believe this formula is used to calculate VE at a given rpm when using air turbine data from a dyno run.

[Matt C]

Having a build with parts that compliment each other,with the proper compression & quality headflow is way more important than CFM amount

As long as the air speed in the intake runner is sub-mach, you're good. Velocity is 10X more important than CFM .
It provides a "ram" effect which can cause VE to exceed 100%. "Ram tuning" is far more effective in filling a cylinder
than the piston pulling the charge in.

[pwmorris]

Having a build with parts that compliment each other,with the proper compression & quality headflow is way more important than CFM amount

As long as the air speed in the intake runner is sub-mach, you're good. Velocity is 10X more important than CFM .
It provides a "ram" effect which can cause VE to exceed 100%. "Ram tuning" is far more effective in filling a cylinder
than the piston pulling the charge in.

This^^^^^^^^^^^^^^^^^^^^^^
That's why I shake my head at "best" cam threads, "best" pipe, etc, as the correct combo (with many variables involved) working together as ONE, always produces the best power and achieves the goal of the owner/builder.
This is also why top race teams, and top street builders and porters consistently make more horsepower than the rest-they know (don't guess) what works and what doesn't. 
My street heads flow well over 400, but that ain't why my street motor makes good power.....it's the head and intake velocity, and the correct combo of parts from valve train all the way down and out the pipe-planned in advance based on the goals of the build.

Some great learning on Speedtalk, as many top pro head guys share knowledge and experiences with similar principles that apply here....
https://speedtalk.com/forum/viewforum.php?f=1

[Matt C]

Jessel rocker/S&S pro stock top ends and SA cases aren't really standard fare around here.
Apples and oranges. But I get the point.

Just thinking out loud...

[build it]

I'm'a put my waders on.

[motolocopat]

Interesting conversation.
My youngest son, 17, has an interest in being a Mechanic and the other day he stated something about Air Flow being important, got me to thinking he's actually read/studied some on the subject. He's not the best at the righty tighty lefty loosey stuff but he's pretty good on Math etc and I've thought he'd be better off more on a design/Engineering path  . . . anyhow I've sent him an email directing him to this thread and bought the book referenced on the matter, and another on Engine Formulas.

[1FSTRK]

Most of the posts mention the importance of velocity, How much velocity do we need?
What is the proper way to calculate intake air velocity?

[pwmorris]

Jessel rocker/S&S pro stock top ends and SA cases aren't really standard fare around here.
Apples and oranges. But I get the point.

Just thinking out loud...

No, apples and apples. My 91 octane, pump gas, no PMS, daily driven street bike motor was the example I mentioned, and yeah, it is ALL S&S (except for CP Pistons).
Principles still apply though-street, strip, dirt, or on the lake or in the snow.

[Matt C]

Jessel rocker/S&S pro stock top ends and SA cases aren't really standard fare around here.
Apples and oranges. But I get the point.

Just thinking out loud...

No, apples and apples. My 91 octane, pump gas, no PMS, daily driven street bike motor was the example I mentioned, and yeah, it is ALL S&S (except for CP Pistons).
Principles still apply though-street, strip, dirt, or on the lake or in the snow.

Yep. The same principles apply whether its a Briggs&Stratton or a Top-Fuel dragster. Its not rocket
science.

[1FSTRK]

 
https://www.youtube.com/watch?v=B0hCHGAiF0g

[build it]

Interesting conversation.
My youngest son, 17, has an interest in being a Mechanic and the other day he stated something about Air Flow being important, got me to thinking he's actually read/studied some on the subject. He's not the best at the righty tighty lefty loosey stuff but he's pretty good on Math etc and I've thought he'd be better off more on a design/Engineering path  . . . anyhow I've sent him an email directing him to this thread and bought the book referenced on the matter, and another on Engine Formulas.

If your son is serious about making power he should read fluid dynamics textbooks and practice with a grinder, I'd recommend air. These forum discussions, specifically on air flow have little to no value. The correlation between static flow at 1psi and performance is tenuous at best, and will lead him down the wrong path at worst.  A lot of cylinder head shops produce results in spite of what they think they know.

Make sure he knows how to measure and take molds. If he goes down this path, not recommended, his ability to measure and track performance will be the sole indicator of success.

The best tools he can have access to are a dyno, burette, indicator, mold making materials, and an ass load of burrs and cartridge rolls. The dyno can wait for now, but track everything typically mentioned in a dyno sheet and CSA. Comparing sheets from one hand port shop to another is a waste of time.

I'd also suggest visiting the local university that has an ME program and ask them what textbooks they use.

[Matt C]

 
Making molds and sectioning them is a great way to see the shape and measure the various sections (number them).

You'll need access to a seat and guide machine as well. You can't do airflow research without being able to cut seats
and try different shapes. (a flowbench helps too).

PS: An engineering program/degree will open up all kinds of doors. Even if it's not directly related to this specific subject,
the job opportunities will be far greater in the long run.

[build it]

Making molds and sectioning them is a great way to see the shape and measure the various sections (number them).

You'll need access to a seat and guide machine as well. You can't do airflow research without being able to cut seats
and try different shapes. (a flowbench helps too).

PS: An engineering program/degree will open up all kinds of doors. Even if it's not directly related to this specific subject,
the job opportunities will be far greater in the long run.

He can farm s&g out for now. Right now he needs grinder and measuring time, nothing else. If the kid is disciplined and has a good work ethic he'll go far.

[Matt C]

Good point (I take that part for granted). You have to walk before you run...

Since he's good in math, I'd try to steer him into an engineering program. But that's
just the old man in me talking. That was the best thing I ever did for myself (next to
marrying my high school sweetie).

Actually, my parents talked me into school. But man, it paid off big.

[thumper 823]

The BIG Picture-
Textbook answers are ok .
But the devil is always in the details.
I have worked very hard at discovering more then what is says on say page 93.
The guy that has applied all of that and 1000 other pages in details will win.
I am not sure what he will win, It is just personal satisfaction for me.
Everything (all most) that will make your engine perform better will never make it last longer.
The novice wants a hi-performance guaranteed to go hundred thousand mile engine.
That is upside down and not going to happen.
Narrow seats, steeper angles, shorter narrowed guides, will outperform the textbook answers.
I have arrived at the 20K mark .
By this I mean I will sell out miles for performance if it will make it 20K mark.
That is about two years for me and just long enough to make me forget all the frustrations last time.
So, guys and gals pick your poisons.

[FXDBI]

The BIG Picture-
Textbook answers are ok .
But the devil is always in the details.
I have worked very hard at discovering more then what is says on say page 93.
The guy that has applied all of that and 1000 other pages in details will win.
I am not sure what he will win, It is just personal satisfaction for me.
Everything (all most) that will make your engine perform better will never make it last longer.
The novice wants a hi-performance guaranteed to go hundred thousand mile engine.
That is upside down and not going to happen.
Narrow seats, steeper angles, shorter narrowed guides, will outperform the textbook answers.
I have arrived at the 20K mark .
By this I mean I will sell out miles for performance if it will make it 20K mark.
That is about two years for me and just long enough to make me forget all the frustrations last time.
So, guys and gals pick your poisons.

Well I disagree to a point, a well built high performance engine should make 50k+. Brother did up a 103 HQ kit years back. 117 tq  111 hp . Engine has 60k on it now and still running strong compression still 210 a cylinder.  Good parts, good recipe good tune and attention to details will get you there. 20k is just enough time to show all the short comings of your endeavors and if it needs a rebuild by then something wasn't done right.  Bob

[Ohio HD]

The BIG Picture-
Textbook answers are ok .
But the devil is always in the details.
I have worked very hard at discovering more then what is says on say page 93.
The guy that has applied all of that and 1000 other pages in details will win.
I am not sure what he will win, It is just personal satisfaction for me.
Everything (all most) that will make your engine perform better will never make it last longer.
The novice wants a hi-performance guaranteed to go hundred thousand mile engine.
That is upside down and not going to happen.
Narrow seats, steeper angles, shorter narrowed guides, will outperform the textbook answers.
I have arrived at the 20K mark .
By this I mean I will sell out miles for performance if it will make it 20K mark.
That is about two years for me and just long enough to make me forget all the frustrations last time.
So, guys and gals pick your poisons.

Well I disagree to a point, a well built high performance engine should make 50k+. Brother did up a 103 HQ kit years back. 117 tq  111 hp . Engine has 60k on it now and still running strong compression still 210 a cylinder.  Good parts, good recipe good tune and attention to details will get you there. 20k is just enough time to show all the short comings of your endeavors and if it needs a rebuild by then something wasn't done right.  Bob

Agree Bob, I pulled the 117 out of my bike with over 40k, hard miles. Still was running like a top. Only removed to make way for the 124 I built.

[thumper 823]

The 20K is an arbitrary number.
Pick one that works for you, and transparently you did.
The bigger point is performance numbers are not linear in longevity.
Sort of like- how long will a dragster engine last compared to your go to town car.
I always get a tickle when the dude says I want this, this,  and that and how long will it all last..............
It is a slippery slope.

[Barrett]

I expect my built S&S engine to last longer than what I had..
Mine isn't on the extreme edge but it will get it done. I hope..
Don't know how much my heads flow but they look good...

[thumper 823]

S&S is not really a HIPO engine.
It is a better engine.
Again John Q Know nothing Public,  would be pissed as hell if he bought a real performance engine
and it needed a top end every two years.
There is no way a very narrow seat way to the top of the valve going to go 50K.
I think that example is agreeable?

[1FSTRK]

This thread sure took a turn. How many bike shows should you be able to do before you need to rebuild a performance street engine?

[thumper 823]

I am not sure as I have never done a show......LOL

[1FSTRK]

How wide is a very narrow seat and what is your spring pressure and cam?

[build it]

I think a performance oriented HD can make more power and last longer than 20k. 50° seats and Ti valves are standard in OE environments, they aren't bleeding edge by any means.

No one is saying the textbook can replace experience. Experience and rigorous study will get you there though, as far as the specific individual can go.

Forums are good for experience based knowledge, IME.

[thumper 823]

I will run right out and measure it for ya...
LOL
Actually Just took it apart and I can give you just a couple number cause I can't remember everything.
I believe the seats are 2/32  way at the top.
Cam is DM 530 with his spring set.
  I measure it about 2.5 years ago..  Brain farts
I am now going to a 50 deg seat angle with perhaps a 3/32 seat..I will not know until a few other items are solved here.
(I need the rockers back from Basily )
Like i said
Don't do what I do if you want a 5oK (mile ) engine.

[FXDBI]

I will run right out and measure it for ya...
LOL
Actually Just took it apart and I can give you just a couple number cause I can't remember everything.
I believe the seats are 2/32  way at the top.
Cam is DM 530 with his spring set.
  I measure it about 2.5 years ago..  Brain farts
I am now going to a 50 deg seat angle with perhaps a 3/32 seat..I will not know until a few other items are solved here.
(I need the rockers back from Basily )
Like i said
Don't do what I do if you want a 5oK (mile ) engine.

Well your doing something wrong if it cant make 50k. Tell us more so we don't make the same mistakes....Bob

[1FSTRK]

I will run right out and measure it for ya...
LOL
Actually Just took it apart and I can give you just a couple number cause I can't remember everything.
I believe the seats are 2/32  way at the top.
Cam is DM 530 with his spring set.
  I measure it about 2.5 years ago..  Brain farts
I am now going to a 50 deg seat angle with perhaps a 3/32 seat..I will not know until a few other items are solved here.
(I need the rockers back from Basily )
Like i said
Don't do what I do if you want a 5oK (mile ) engine.

So how many horse do you honestly feel all this will yield at the rear wheel?
Sounds like a lot of work to give up longevity and gain little. 

[thumper 823]

Like I said, I do this for my own satisfaction.
I have no clue what TQ/Hp is as there is no dyno available here.
I could travel a 100 miles...I guess I am not that interested.
Next-milage
I have no clue how long the TBO would actually be, But my goal is always at least 20K miles.

Everyone says a Harley cannot beat a Honda F6
I own one and this POS Road king makes it look like it is going backward.
Ths F6 is so wimpy in comparison i seriously considering selling it.'Quite disappointing really.

[1FSTRK]

How would you know if something you try makes an improvement?

[pwmorris]

I think it's great Thumper that you are out there, testing, testing, testing and more testing stuff. Fail, succeed, fail, succeed-No Dyno, no problem. Sure it would be a lot easier to evaluate changes but, "Potty mouth", Just take it out on the open road or a track and rip it-you will learn what works, and what doesn't. BTW, there was an AHDRA pro stock champ who never put his bike on the Dyno during his championship year run...
You are actually exploring the possibilities and potential of your motor, not playing keyboard commando and never doing anything.
Depends on many factors how long they last, but my current street bike motor lasted about 30k hard core miles till it needed a rebuild....must have been all the "shows" the bike was in that wore it out-

[thumper 823]

I a not here to Bragg.
THE BIKE  goes like hell.
I will dyno it this summer after back together as I have done enough changes to warrant the cost.
Speaking of my 20K mark.......
i installed a 12 lb ring pack thinking this might be my biggest mistake .
Truly I was on the fence about it .
I have been to Sturgis twice with it same rings and about 2oK all told.
It uses a QT in about 2500 miles .
Now some people would say that is HORRIBLE!
I say that is freeking    TERRIFIC!
This engine sees at least 15 lbs less friction then most.

[thumper 823]

I think it's great Thumper that you are out there, testing, testing, testing and more testing stuff. Fail, succeed, fail, succeed-No Dyno, no problem. Sure it would be a lot easier to evaluate changes but, "Potty mouth", Just take it out on the open road or a track and rip it-you will learn what works, and what doesn't. BTW, there was an AHDRA pro stock champ who never put his bike on the Dyno during his championship year run...
You are actually exploring the possibilities and potential of your motor, not playing keyboard commando and never doing anything.
Depends on many factors how long they last, but my current street bike motor lasted about 30k hard core miles till it needed a rebuild....must have been all the "shows" the bike was in that wore it out-

I do have AFR gauge ....it is almost a dyno..LOL
The two dyno people sort of close to me have given me a bunch of shet..I was going to dyno it last summer.....
But one operator thought the twin plugs were a novel idea and great for emissions.
No clue.
Both operators wanted it to come off the rack with a tune of 13.5
I am not the smartest there is...but not the dumbest either.
There is no way I could run this thing that lean.
So no it was not dynoed

[thumper 823]

I will run right out and measure it for ya...
LOL
Actually Just took it apart and I can give you just a couple number cause I can't remember everything.
I believe the seats are 2/32  way at the top.
Cam is DM 530 with his spring set.
  I measure it about 2.5 years ago..  Brain farts
I am now going to a 50 deg seat angle with perhaps a 3/32 seat..I will not know until a few other items are solved here.
(I need the rockers back from Basily )
Like i said
Don't do what I do if you want a 5oK (mile ) engine.

Well your doing something wrong if it cant make 50k. Tell us more so we don't make the same mistakes....Bob

No not at all , you just are not understanding the subject matter.
If I was shooting for long, longevity I would do like the diesel and most aircraft engines do, a 35 deg seats.
Hvy sodium valves.
Aunt tillies 3o lb ring pack, cheap cast slugs .
And a few other mods.
Harley comes to you with a detuned engine and then wants to sell you stuff to bring it to par.
Rule of thumb  -one cubic inch per hp, is way safe, too safe, considering some crotch rockets are upwards and past 3 HP per cube.
However, they have no internal RPM governor.
I am hoping i am in the 1.3 Hp per cube area.
With as much as I have done I think that is a conservative guess.
But it is just a guess without the papers.

[1FSTRK]

I will run right out and measure it for ya...
LOL
Actually Just took it apart and I can give you just a couple number cause I can't remember everything.
I believe the seats are 2/32  way at the top.
Cam is DM 530 with his spring set.
  I measure it about 2.5 years ago..  Brain farts
I am now going to a 50 deg seat angle with perhaps a 3/32 seat..I will not know until a few other items are solved here.
(I need the rockers back from Basily )
Like i said
Don't do what I do if you want a 5oK (mile ) engine.

Well your doing something wrong if it cant make 50k. Tell us more so we don't make the same mistakes....Bob

No not at all , you just are not understanding the subject matter.
If I was shooting for long, longevity I would do like the diesel and most aircraft engines do, a 35 deg seats.
Hvy sodium valves.
Aunt tillies 3o lb ring pack, cheap cast slugs .
And a few other mods.
Harley comes to you with a detuned engine and then wants to sell you stuff to bring it to par.
Rule of thumb  -one cubic inch per hp, is way safe, too safe, considering some crotch rockets are upwards and past 3 HP per cube.
However, they have no internal RPM governor.
I am hoping i am in the 1.3 Hp per cube area.
With as much as I have done I think that is a conservative guess.
But it is just a guess without the papers.

My guess is you read a lot and talk to a lot of knowledgeable people.
If you stay away from flow benches, dynos, as well as professionally built engines and components your projected hp will continue to go up and up. You will continue to happily work on your bike all winter and ride with a smile all summer long.

[Matt C]

There's a guy on youtube, Tatro Machine. You should check him out (he doesn't believe in Dyno and Flowbench testing) Uses his 'fingers' to predict airflow patterns. I don't know why some Nascar team hasn't snapped up this
genius. 

[1FSTRK]

There's a guy on youtube, Tatro Machine. You should check him out (he doesn't believe in Dyno and Flowbench testing) Uses his 'fingers' to predict airflow patterns. I don't know why some Nascar team hasn't snapped up this
genius. 

Don't knock it if you have not tried it, your finger is very sensitive to air flow and is invaluable when picking which direction to face when peeing outdoors.

[Matt C]

The BIG Picture-
Textbook answers are ok .
But the devil is always in the details.
I have worked very hard at discovering more then what is says on say page 93.
The guy that has applied all of that and 1000 other pages in details will win.
I am not sure what he will win, It is just personal satisfaction for me.
Everything (all most) that will make your engine perform better will never make it last longer.
The novice wants a hi-performance guaranteed to go hundred thousand mile engine.
That is upside down and not going to happen.
Narrow seats, steeper angles, shorter narrowed guides, will outperform the textbook answers.
I have arrived at the 20K mark .
By this I mean I will sell out miles for performance if it will make it 20K mark.
That is about two years for me and just long enough to make me forget all the frustrations last time.
So, guys and gals pick your poisons.

Narrow seats, steeper angles, shorter narrowed guides? (That stuff is in text books, if you look for it).

That crap is for unlimited budget racers *Nascar for example*. We don't need any of that crap for
these low RPM street driven engines. Keep it simple, ride it sanely and they'll last a long time.   

[Matt C]

Anything that increases the efficiency of the engine will make it last longer. It's when you start raising
the engine's operating RPM range that potentially shortens its life.

Engine blueprint, quality parts, break-in and good maintenance all will extend it's life. Along with riding
it sanely. I have 25,000 on my Dyna and it's never been into. Just oil changes and routine maintenance.

I do plan on going into it before I ride it this year b/c it's probably due (lol). And, since I'm going to be in
there; better heads, cams, gear drives and BB kit are going on it. It will last another 40K at least after that.
 

[thumper 823]

The subjects seem to get turned around here.
Sort of into insults, and I in no way have tried to do that to anyone...
So whatever makes you all happy.
Nothing I have done has not been done others, somewhere else.
I am no genius, just rather predictably always looking for better.
I do study a lot, Smokey Yunick should be on everyone's shelf.
The saying I use is "it is VERY hard to bolt on horsepower ".
I think I may have stolen that too from perhaps Corky Bell.
To the point-
We all want more power, it comes with cost .
Like I said B4, - 20K miles is a good number for me, it allows ideas outside the box of conformity.
No one is going to do anything different by repeating the stuff over and over.Again .
Shaving heads 50 thou, 10.5 CR, bigger carbs and pipes.........sending heads out for thousand dollar port jobs
Is all stuff that can be done at home.

[thumper 823]

Anything that increases the efficiency of the engine will make it last longer. It's when you start raising
the engine's operating RPM range that potentially shortens its life.

Engine blueprint, quality parts, break-in and good maintenance all will extend it's life. Along with riding
it sanely. I have 25,000 on my Dyna and it's never been into. Just oil changes and routine maintenance.

I do plan on going into it before I ride it this year b/c it's probably due (lol). And, since I'm going to be in
there; better heads, cams, gear drives and BB kit are going on it. It will last another 40K at least after that.

I cannot agree with that, as a IC engine is about 20% efficient.
Example-Drain the water out of your car and will be more efficient, but will not last very long.
Everything is a trade-off. Compromise.
That is why all the R&D has been going into ceramic engines-no liquid cooling just hotter.
If we ask more from most anything we get it but the time ticks away faster on the other end.

[build it]

Thumper, I applaud what you're doing and encourage you to go further with each succcessive build. Make sure those seats are concentric and vacuum test the head. You're on the right path and just might be surprised upon freshen if you follow good principles.

[thumper 823]

Thanx !
The  Devil is in the details.
No production shop will ever treat your heads like their own.
Simple.
That is why I encourage everyone to buy a hard seat grinder and needed pilots /stones.
Used is cheap on eBay.
Do your own work and this will no longer baffle you.
Then, one is willing to try some other stuff. Like narrow short guides.
Its just no big deal along with whatever other tricks might be applied.

[Matt C]

The subjects seem to get turned around here.
Sort of into insults, and I in no way have tried to do that to anyone...
So whatever makes you all happy.
Nothing I have done has not been done others, somewhere else.
I am no genius, just rather predictably always looking for better.
I do study a lot, Smokey Yunick should be on everyone's shelf.
The saying I use is "it is VERY hard to bolt on horsepower ".
I think I may have stolen that too from perhaps Corky Bell.
To the point-
We all want more power, it comes with cost .
Like I said B4, - 20K miles is a good number for me, it allows ideas outside the box of conformity.
No one is going to do anything different by repeating the stuff over and over.Again .
Shaving heads 50 thou, 10.5 CR, bigger carbs and pipes.........sending heads out for thousand dollar port jobs
Is all stuff that can be done at home.

I wasn't insulting anyone, sorry if you took it that way. Just trying to add common sense perspective.
If you can do a "$1000" port job yourself, more "power" to ya.

Power comes with cost, yes. But allot of ppl operate under a false assumption that if it costs more, it has
to be better.

I spend 80% of my time doing R&D because it's what I'm into. I'm not in it for money. I'm retired and have
that covered. I do it b/c I enjoy the challenge. A Flowbench and a Dyno is what I use to develop cylinder
heads.

If you think you can to a "$1000 port job" with stones and no flowbench, that's great. You're smarter than
99% of the people out there.

Have a nice new year.

[No Cents]

   so...your saying no head porters are needed like wfolarry, J Sachs, Jim Libo, or even Dave Ward...just to name a few off the top of my head. 
Just do it yourself huh?
  You say these guys won't show you their best work. That's a pretty bold statement...and I have to disagree with you. They will give you their best work...but you have to pay for it. Horsepower doesn't come cheap or free. I leave things like head porting to the professionals. Tell them what your after...and set back and let them do their thing. These guys got to where they are today by hard work and constantly experimenting to find more. I'd rather pay them for their knowledge and expertise, rather than me ruin a good set of heads by me trying to improve the velocity and flow with no way to test it besides bolting it together and running it down the road to see if I felt an improvement. I guess if it was a full time drag bike you could tune it according to results your seeing off the strip. But a bike ran on the street I'd want it on a dyno for break in while it's being monitored. Too lean, or too rich can be destroying your engine without you even knowing it.
   I know Nascar teams use high dollar wet flow bench's to actually see what's going on inside the heads. They will make very small changes, one at a time, and then re-evaluate after seeing the results. It's a never ending process they do to try to gain more power. They have full time design engineers and machinist working on this every day.

[thumper 823]

More money should get more power.
But more often than not it dont!
for instance-
The 400.00 dollar air cleaners .....
I wish I could tell people......what a waste

[thumper 823]

   so...your saying no head porters are needed like wfolarry, J Sachs, Jim Libo, or even Dave Ward...just to name a few off the top of my head. 
Just do it yourself huh?
  You say these guys won't show you their best work. That's a pretty bold statement...and I have to disagree with you. They will give you their best work...but you have to pay for it. Horsepower doesn't come cheap or free. I leave things like head porting to the professionals. Tell them what your after...and set back and let them do their thing. These guys got to where they are today by hard work and constantly experimenting to find more. I'd rather pay them for their knowledge and expertise, rather than me ruin a good set of heads by me trying to improve the velocity and flow with no way to test it besides bolting it together and running it down the road to see if I felt an improvement. I guess if it was a full time drag bike you could tune it according to results your seeing off the strip. But a bike ran on the street I'd want it on a dyno for break in while it's being monitored. Too lean, or too rich can be destroying your engine without you even knowing it.
   I know Nascar teams use high dollar wet flow bench's to actually see what's going on inside the heads. They will make very small changes, one at a time, and then re-evaluate after seeing the results. It's a never ending process they do to try to gain more power. They have full time design engineers and machinist working on this every day.

you read more into that then I actually said.

I have raced a couple people that had Brand X  do their heads.
They were quite pissed.
All i am saying is most people can do a lot of the work for a lot less. (if they put their mind to it)
They might not do as well  as Mondello, but they are off to some satisfaction.

[Matt C]

   so...your saying no head porters are needed like wfolarry, J Sachs, Jim Libo, or even Dave Ward...just to name a few off the top of my head. 
Just do it yourself huh?
  You say these guys won't show you their best work. That's a pretty bold statement...and I have to disagree with you. They will give you their best work...but you have to pay for it. Horsepower doesn't come cheap or free. I leave things like head porting to the professionals. Tell them what your after...and set back and let them do their thing. These guys got to where they are today by hard work and constantly experimenting to find more. I'd rather pay them for their knowledge and expertise, rather than me ruin a good set of heads by me trying to improve the velocity and flow with no way to test it besides bolting it together and running it down the road to see if I felt an improvement. I guess if it was a full time drag bike you could tune it according to results your seeing off the strip. But a bike ran on the street I'd want it on a dyno for break in while it's being monitored. Too lean, or too rich can be destroying your engine without you even knowing it.
   I know Nascar teams use high dollar wet flow bench's to actually see what's going on inside the heads. They will make very small changes, one at a time, and then re-evaluate after seeing the results. It's a never ending process they do to try to gain more power. They have full time design engineers and machinist working on this every day.

Yeah Ray, that's the way I read it.

I sometimes spend 40-50 hours a week, flowbench testing (on one port). Trying very small incremental
changes. Seat profiles, short side shapes, valve shapes wet flow, etc & so-on...

I think if you told Smokey he didn't need a flowbench, he would have laughed you out of his shop. Smokey was
one of the pioneers of flowbenches. Very sharp guy and ahead of his time. He held many many patents as well.

His books are very good too.

Joe Mondello was another one, he was a good friend and a mentor to me.

[thumper 823]

Where did I say "No flow bench needed?"
You all hung over?
I have seen some hacks with flow benches too.
Snake oil comes in various containers.

[No Cents]

     Matt...I wasn't fortunate enough to ever meet Joe Mondello...but I did get the chance to talk to him on the phone once. He impressed the hell out of me after he took the time out to talk to a nobody like me. I was humbled. He was a very smart man. 

[Matt C]

     Matt...I wasn't fortunate enough to ever meet Joe Mondello...but I did get the chance to talk to him on the phone once. He impressed the hell out of me after he took the time out to talk to a nobody like me. I was humbled. He was a very smart man. 

He was awesome, (I was devastated when he passed). The really good ones, will take the time to pass their
knowledge on willfully. I went to a couple of his classes/seminars, that was a chance of a lifetime.

I had the honor of meeting Darin Morgan last year, and I managed to get into his advanced induction system
design course.

He's allot like Joe. Very down to earth and will show you everything and anything you want to know and stuff
you didn't think you wanted/needed to know. Highly recommend that one, if you can get in.

[kd]

Thumper, you can't compare what happens in a race based solely on how the heads turned out (no matter who did them). There are too many other parts to the equation like compression, cam specs, intake, pipe, tune yadda yadda yadda.

If anyone can get some book learnin on how to pull air around a short side, how long to cut the seat angles and how many if any, what and where the CSA should be, (and on and on) ..... then pull out their Harbour Freight grinder and produce a set of heads that are even close to the same as WFO, Dan Baisley, Don or any of the others considered worthy professionals you should be on stage telling jokes. Seriously, I can't get my head around that any one can believe that. Valve jobs .... OK. Change guides ..... sure, follow the instructions.  To know by appearance (through experience) how to pull up the torque #'s when that is the riding style or get the most out of a certain cam spec to get that 1/10 of a second in 1320 does not happen in your first or even 10th set of heads.  All I can see here is a bin full of aluminum castings on the way to the recyclers. That is of course unless what you are really talking about is cleaning up the port castings and doing typical valve jobs.  That is doable.

I hope that no one starts thinking they can do head work better than "Brand X" (if they are a proven porter) because they read somewhere there is nothing to it. Having said all that, I am only trying to say THERE IS NO SUBSTITUTE for a set of heads custom ported and massaged by one of the top porters who's names we generally throw around here. The money is ALWAYS well spent when you are trying to pull 1.25 or there about out of a build. Top tier engines require top tier work. That's a well known fact.

If you have read and studied head porting techniques you will likely be able to have a well educated discussion with a top porter and subsequently get more of what you are after in the end from that porter. That's about it. Doing the work involves a huge amount of learning hands on and testing to confirm success or failure.   My 2 cents 

[build it]

Thanx !
The  Devil is in the details.
No production shop will ever treat your heads like their own.
Simple.
That is why I encourage everyone to buy a hard seat grinder and needed pilots /stones.
Used is cheap on eBay.
Do your own work and this will no longer baffle you.
Then, one is willing to try some other stuff. Like narrow short guides.
Its just no big deal along with whatever other tricks might be applied.

You’re doing guide work first, correct?

I dig that you’re using stones plenty to be said about that, all positive.

If you have a good foundation and principles no reason you can’t go as far as you want to go. In my experience a lot of people especially on forums make port work sound like magic, it isn’t, all it is is area scheduling.

That’s my last post in this thread.

[kd]

     Matt...I wasn't fortunate enough to ever meet Joe Mondello...but I did get the chance to talk to him on the phone once. He impressed the hell out of me after he took the time out to talk to a nobody like me. I was humbled. He was a very smart man. 

He was awesome, (I was devastated when he passed). The really good ones, will take the time to pass their
knowledge on willfully. I went to a couple of his classes/seminars, that was a chance of a lifetime.

I had the honor of meeting Darin Morgan last year, and I managed to get into his advanced induction system
design course.

He's allot like Joe. Very down to earth and will show you everything and anything you want to know and stuff
you didn't think you wanted/needed to know. Highly recommend that one, if you can get in.

I had a similar experience with Dan Baisley over a period of phone calls looking for head work. Once he found my level of understanding, he explained what he would do to satisfy my needs and qualified it with examples. He then delivered in spades. Best money I spent on my 120 as far as I am concerned.

[Matt C]

Thanx !
The  Devil is in the details.
No production shop will ever treat your heads like their own.
Simple.
That is why I encourage everyone to buy a hard seat grinder and needed pilots /stones.
Used is cheap on eBay.
Do your own work and this will no longer baffle you.
Then, one is willing to try some other stuff. Like narrow short guides.
Its just no big deal along with whatever other tricks might be applied.

You're doing guide work first, correct?

I dig that you're using stones plenty to be said about that, all positive.

If you have a good foundation and principles no reason you can't go as far as you want to go. In my experience a lot of people especially on forums make port work sound like magic, it isn't, all it is is area scheduling.

That's my last lost in this thread.

There's nothing wrong with stones, I still have the set I bought in 1973. The only downside(s) I can think of,
is they can't do radius seats, and it takes a little longer. Other than that they're fine. I still use them on quickie passenger car heads if the guides are good.

If I have to heave the damn thing on the machine for guides, then I'll do the seats too while its on there.
car heads

[Hossamania]

For me, I pay someone else for their knowledge and skill, and I do all the small things I can. I do not chase all the horsepower anymore, just enough to beat my friends.
I don't have the time, patience, or money to practice all the little details to squeeze every horse out of an engine, but I sure appreciate the guys that do.

A friend of mine got his kid into go-cart racing. We are talking the low end of the carting ladder. But, he wanted his kid to be competitive (not even close at the beginning), and asked for a little help from some of the other fathers. He got the coldest shoulder possible. He couldn't believe it.
He asked me what to do, so I said to start talking to others in the industry, search the net, and he and I talked often about theory and actual specs.
One of my favorite contributions was clutch mods, shaving it to the minimum spec (using a cordless drill, a vise, and some sandpaper!) to help with the starting line launch. So many other small mods. One of the best things he did was take it to a guy to set up the chassis, and learn how to adjust it himself, keeping tight notes.
Long story short, by the end of the year, he was starting to win races, and the next three years his kid was series champ and traveling out of state to compete nationally. I was proud of him, and a little proud myself that I could make some contribution to his kid's success.
Beating those dicks that wouldn't help at the beginning was the best reward.

Now he wants to get back into riding, and Harleys especially. He already is asking me how to make more horsepower before he even has a bike.
And so it continues!!

[thumper 823]

I use a combination of stones/cutters and other stuff., like most anyone
Depending what I am doing.
The Porsche stuff is very exacting.

[Don D]

"I wasn't fortunate enough to ever meet Joe Mondello.."
I was when he blew my doors off with an Olds vs my LS6 powered GTO at Lyons drag strip in 1970 on a Wednesday night tune up grudge deal.

Thumper
I applaud the "dare to be different" mind set, truly. Go give it hell.

Problem I see, which in time and with money spent will all lay out, is the areas targeted and your ideas are the highest on the tree of where to find horsepower and a lot of the low hanging fruit are left unpicked. I have been presented with heads many times and asked "how do they look"? Somethings I see glaring mistakes that will obviously cost power and/or cause serious running issues and tuning but I keep my mouth shut and throw them on the bench. What I usually do though while the guy is there is take a cleaned stock head and valves and test that as a baseline then theirs. Not only the flow numbers but the sound of the port and stability of the water column at different lifts can tell a lot. If one is acting up then taking a welding rod with an eye bent in the end and probing the port can often times locate the hot spot and smooth it right out. They are amazed that their jewels that had so many hours in them didn't pan out too well and could add 10cfm or whatever with a flow ball or an intrusion in the port. The bench is not the end all be all however. We already covered velocity and the importance of that but in the context of the proper CSA for the application. It is very possible to have a huge port with impressive flow but it doesn't work well for the application. Plus when you have the benefit of a bench and pitot probe you can find the hot spots and fix them so the flow is smooth and balanced throughout the port. Not high tech but how can you find these trouble areas with a set of calipers and grinder? David Vizard probably has written about making cheap flow benches. I know he has done this with big shop vacs. Its' better than nothing. There are plans all over the net for benches that are not costly. That and Betts book will get you a long ways faster than change try and change again. It will also help you choose what is the lower hanging fruit more intelligently related to the heads and airflow.

Good luck in your pursuit.

[Matt C]

  well put, Don.

Added: I'll pull up a test of a stock head saved on the machine and overlay that on top
of customers' test head on the computer screen.

(Same difference, it just saves me from having to test a stock head over and over.)
Seeing it on a screen it really stands out.

[thumper 823]

I will leave the thread bashers this -
Dyno day with the Porche club 
My 2.7 flat 6  pulled all most as much as a 3.0
Harley leaves a LOT on the table or junk in the head.
Porsche does not.
I beat the devil.

[FXDBI]

I will leave the thread bashers this -
Dyno day with the Porche club 
My 2.7 flat 6  pulled all most as much as a 3.0
Harley leaves a LOT on the table or junk in the head.
Porsche does not.
I beat the devil.

   Tell us how you really feel!   Bob

[sfmichael]

I will run right out and measure it for ya...
LOL
Actually Just took it apart and I can give you just a couple number cause I can't remember everything.
I believe the seats are 2/32  way at the top.
Cam is DM 530 with his spring set.
  I measure it about 2.5 years ago..  Brain farts
I am now going to a 50 deg seat angle with perhaps a 3/32 seat..I will not know until a few other items are solved here.
(I need the rockers back from Basily )
Like i said
Don't do what I do if you want a 5oK (mile ) engine.

been doing heads for years (not high volume #'s) and I'm happy with a 2/32(?) or what I would call a 1/16 or .060+ seat width

I never put it at the very top of the valve edge as to allow for run-in, or a little recession, but longevity has never been a problem

to the op's point: CFM requirement for me is determined by my overall goals

really big hp can't be achieved without really good heads, but I tailor the heads to the rest of the motor in terms of budget and desired outcome'

yes, thumper, the devil is in the details and that holds true to most things in life if you wish to rise above mediocrity

you can get 'okay' anywhere - excellence must be earned / striven for

[Matt C]

I don't see any "hating" going on, did I doze off and miss something?

[sfmichael]

I don't see any "hating" going on, did I doze off and miss something?

...you might have?    I do it all the time

[Matt C]

I don't see any "hating" going on, did I doze off and miss something?

...you might have?    I do it all the time

lmao! That happens to old farts like me. Just checking. Thanks!

[kd]

I don't see any "hating" going on, did I doze off and miss something?

...you might have?    I do it all the time

lmao! That happens to old farts like me. Just checking. Thanks!

The title of the thread does have "Vs" in it.    Usually technical discussions (on here) have more than one opinion. Therein lies the basis of discovery. Some don't see it that way I guess and feel like they are being dissed for having a different view.    That's what I liked about Max when he was around more. He made you think (and learn) and he certainly was more to the point than gentle. We're all getting soft without him watching over us as often. Maybe this year he'll spend more time with us and knock us back into shape?

Now back to the thread    Head CFM vs. HP per c.i.?  I was trying to learn somethin.     

[Matt C]

Here's a link to some reading that may (or may not) help. There's other links to all kinds of
stuff at: wallaceracing.com It has calculators to help/confuse you even more. If nothing
else, this may help put you to sleep, or keep you up at night. Read it at your own risk!

http://garage.grumpysperformance.com/index.php?threads/port-speeds-and-area.333/

Enjoy,

[1workinman]

I not sure how much cfm it takes to make xxx horse power and torque , but the easiest way I know of is call your favorite porter , discuss your goals . Open up check book . I know what my heads flow.  They done the build several times and its repeatable . For me I just saw a build that I liked and I just copied it or very close. I know that not the answer to the question . That is one of the reasons why I like this forum , as much as I like the guys at the local Harley dealer I doubt they ever heard of the porters Ray mentioned . 

[pwmorris]

Joe Mondello was another one, he was a good friend and a mentor to me.

Mondello did this handmade plenum manifold for a build I ran years back. Very well done, and worked well.

I not sure how much cfm it takes to make xxx horse power and torque , but the easiest way I know of is call your favorite porter , discuss your goals . Open up check book . I know what my heads flow.  They done the build several times and its repeatable . For me I just saw a build that I liked and I just copied it or very close. I know that not the answer to the question . That is one of the reasons why I like this forum , as much as I like the guys at the local Harley dealer I doubt they ever heard of the porters Ray mentioned . 

Nope, they have no clue, as well as several Ray didn't mention. Virtually all Harley dealer guys wouldn't know 425 cfm intake head flow from 425 cubic inches...lol....

[Jonny Cash]

Joe Mondello was another one, he was a good friend and a mentor to me.

Mondello did this handmade plenum manifold for a build I ran years back. Very well done, and worked well.

I not sure how much cfm it takes to make xxx horse power and torque , but the easiest way I know of is call your favorite porter , discuss your goals . Open up check book . I know what my heads flow.  They done the build several times and its repeatable . For me I just saw a build that I liked and I just copied it or very close. I know that not the answer to the question . That is one of the reasons why I like this forum , as much as I like the guys at the local Harley dealer I doubt they ever heard of the porters Ray mentioned . 

Nope, they have no clue, as well as several Ray didn't mention. Virtually all Harley dealer guys wouldn't know 425 cfm intake head flow from 425 cubic inches...lol....

cool intake! Interesting that the throttle blade centerline is above the intake port centerline. hmmm. I would like to try this on an injected setup if I can clearance the fuel tank enough for IAC clearance.

[Don D]

Back to the OP
Consider PipeMax software. A cheap tool that will calculate the port area and show velocity with the cubic inch parameters input.

[Barrett]

     Matt...I wasn't fortunate enough to ever meet Joe Mondello...but I did get the chance to talk to him on the phone once. He impressed the hell out of me after he took the time out to talk to a nobody like me. I was humbled. He was a very smart man. 

He was awesome, (I was devastated when he passed). The really good ones, will take the time to pass their
knowledge on willfully. I went to a couple of his classes/seminars, that was a chance of a lifetime.

I had the honor of meeting Darin Morgan last year, and I managed to get into his advanced induction system
design course.

He's allot like Joe. Very down to earth and will show you everything and anything you want to know and stuff
you didn't think you wanted/needed to know. Highly recommend that one, if you can get in.

While searching for my flow numbers a few days ago I found a link with multiple heads listed.
Darin has race heads listed as 691/375@1" lift.. I'll bet they're kinda soft on the bottom tho..

http://www.users.interport.net/s/r/srweiss/tablehdc.htm#Harley-Davidson

[1workinman]

Joe Mondello was another one, he was a good friend and a mentor to me.

Mondello did this handmade plenum manifold for a build I ran years back. Very well done, and worked well.

I not sure how much cfm it takes to make xxx horse power and torque , but the easiest way I know of is call your favorite porter , discuss your goals . Open up check book . I know what my heads flow.  They done the build several times and its repeatable . For me I just saw a build that I liked and I just copied it or very close. I know that not the answer to the question . That is one of the reasons why I like this forum , as much as I like the guys at the local Harley dealer I doubt they ever heard of the porters Ray mentioned . 

Nope, they have no clue, as well as several Ray didn't mention. Virtually all Harley dealer guys wouldn't know 425 cfm intake head flow from 425 cubic inches...lol....

cool intake! Interesting that the throttle blade centerline is above the intake port centerline. hmmm. I would like to try this on an injected setup if I can clearance the fuel tank enough for IAC clearance.

I chatted with a fellow from SA racing about some head work and the intake work is one of the things that was discussed . Smart guy

[pwmorris]

     Matt...I wasn't fortunate enough to ever meet Joe Mondello...but I did get the chance to talk to him on the phone once. He impressed the hell out of me after he took the time out to talk to a nobody like me. I was humbled. He was a very smart man. 

He was awesome, (I was devastated when he passed). The really good ones, will take the time to pass their
knowledge on willfully. I went to a couple of his classes/seminars, that was a chance of a lifetime.

I had the honor of meeting Darin Morgan last year, and I managed to get into his advanced induction system
design course.

He's allot like Joe. Very down to earth and will show you everything and anything you want to know and stuff
you didn't think you wanted/needed to know. Highly recommend that one, if you can get in.

While searching for my flow numbers a few days ago I found a link with multiple heads listed.
Darin has race heads listed as 691/375@1" lift.. I'll bet they're kinda soft on the bottom tho..

http://www.users.interport.net/s/r/srweiss/tablehdc.htm#Harley-Davidson

5 1/8 bore, S&S 160" billet Prostocks-
Yeah, at over 2.2 HP per Cube, they move some air, but since they make their power from 5,500-9 grand, well, they wouldn't be so good in the typical bagger

[aswracing]

Is there a standard of how much HP you should be able to achieve given the amount of CFM your heads flow? Meaning, if your head flows 300CFM you can achieve (x) hp ci.

If I had a nickel for every time I made a change, saw the flow go one direction, and saw the power go the opposite direction, I'd have like a ton of nickels.

And it's not just about port size and velocity ...



This experimental valve job really hurt the flow bench numbers, low lift to high lift. No changes to the port. We almost didn't even dyno test it, we didn't think it would be worth the trouble. The dyno had a whole different opinion from the flow bench.


Here's another example of the flow bench being a poor predictor of results:



We had a valve vendor trying to win our business. Offered us some high quality valves for considerably less than we were already paying. This was a test of the intake valve, that's the only thing we changed. We put it on the flow bench and there wasn't a dime's worth of difference as compared to our current valves. Good thing we dyno tested them before we made a decision.

What's really going on here is that the flow bench does a piss poor job of reproducing what's actually happening in a motor. Motors don't sit there and hold a nice steady cylinder pressure no matter what the valve lift or where in the cycle you are. A cylinder pressure chart shows that clearly:



This is from one of Vizard's books. Look at the cylinder pressure. As the valve is coming off the seat and the exhaust is pulling, you can exceed 100" of depression. Does your flow bench measure what's going on at 100" and .075" lift? No, a flow bench throttles down at low lifts to maintain a constant 28" or 10". But that's not what a motor does. Air acts very differently with 100" as compared to 28" or 10".

I'm not saying it's a useless tool, hell, we use one every day. But it's not the whole story, as many people seem to assume. It's entirely possible to go one direction on the flow bench and go the opposite direction on the dyno, even without changing the port size or shape.

We really need a better tool, one that can actually reproduce what the motor is doing.

[Matt C]

That's very accurate information Aaron.

The flow at Overlap lift (whatever it ends up being) is 'under appreciated' or not considered in
allot of cases. The overlap event (the fifth cycle of a four cycle engine) is where all the magic
starts to happen. (It's also where some undesirable things can occur as well).

I agree that Flowbenches are only an approximation and in no way can duplicate what goes on
in a running engine. Dyno testing is the best thing we have. I've been disappointed many times
by dyno results compared to FB results, but that's how we learn.

I quit chasing peak CFM numbers b/c they don't equate to area under the TQ curve.

General Motors had a test cell that would pull 200+" of WC for testing this type of thing, but good
luck getting any of that research. Bottom line is, the overlap event is probably the most important
of all. IC being a distant second.

Good info, thanks!

[thumper 823]

There are people with talent out there.
Measuring what it takes to fill two cylinders 30 to 50 times a second, one has to see air.
Understand it.
Not just a carver and a re do and a retry.
It is not just a soft breeze at that speed.
But is material doing odd and strange things.
There was a guy over at Skunkworks and it was said he did just that!
Reynolds and Burnalie are a living thing to some people,, not just a number pulled from the wind tunnel.

Of course, i am speaking of the Great  Kelly Johnson,

Quote-" was pugnacious, stubborn, serious and combative. Yet he had an almost artistic flair for matters aeronautical. One of his bosses remarked that Johnson could "see air." His successor, Ben Rich, commented on Johnson's more earthy side this way:"      End Q

[Timinator]

The closest way I have found to really "see" air is to jump through it. I ported for about 18 + years before I ever decided to skydive. Those 430+ jumps in the last 25 years didn't allow me to see air, but it gives me a better idea of what is happening in a port. What little nuances in finger/hand position and what clothing you wear will do to your entire body attitude and fall speed. Playing catch with a weighted ball in a breeze of 110+ mph gives you a far different perspective of what air is capable of. I have never thought of air and its mass in the same way since.
We all know that what a port sounds like at max flow is important to flow and quality, imagine being inside of a port and feeling and listening to what is going on around you. Porting, as life, is about perspective and perception. Anything that helps with that will be a big plus. 
Study: Boyle, Gay-Lussac, Hilsch, and Bernoulli for insights into air and its properties. You'll be miles ahead in the porting game, not just if you are a porter, but it will also allow you to better analyze ports when you look at them.      TIMINATOR

[build it]

Is there a standard of how much HP you should be able to achieve given the amount of CFM your heads flow? Meaning, if your head flows 300CFM you can achieve (x) hp ci.

If I had a nickel for every time I made a change, saw the flow go one direction, and saw the power go the opposite direction, I'd have like a ton of nickels.

And it's not just about port size and velocity ...



This experimental valve job really hurt the flow bench numbers, low lift to high lift. No changes to the port. We almost didn't even dyno test it, we didn't think it would be worth the trouble. The dyno had a whole different opinion from the flow bench.


Here's another example of the flow bench being a poor predictor of results:



We had a valve vendor trying to win our business. Offered us some high quality valves for considerably less than we were already paying. This was a test of the intake valve, that's the only thing we changed. We put it on the flow bench and there wasn't a dime's worth of difference as compared to our current valves. Good thing we dyno tested them before we made a decision.

What's really going on here is that the flow bench does a piss poor job of reproducing what's actually happening in a motor. Motors don't sit there and hold a nice steady cylinder pressure no matter what the valve lift or where in the cycle you are. A cylinder pressure chart shows that clearly:



This is from one of Vizard's books. Look at the cylinder pressure. As the valve is coming off the seat and the exhaust is pulling, you can exceed 100" of depression. Does your flow bench measure what's going on at 100" and .075" lift? No, a flow bench throttles down at low lifts to maintain a constant 28" or 10". But that's not what a motor does. Air acts very differently with 100" as compared to 28" or 10".

I'm not saying it's a useless tool, hell, we use one every day. But it's not the whole story, as many people seem to assume. It's entirely possible to go one direction on the flow bench and go the opposite direction on the dyno, even without changing the port size or shape.

We really need a better tool, one that can actually reproduce what the motor is doing.

I'm glad you said it first! I've seen data that would have some guys lose their hair trying to figure out what went "wrong", and worse yet, try to "fix" the port with disasterous results. I used to dream of having a little mom and pop shop, now all I can do is work to pay for my own RD because I have to many damn questions!

[thumper 823]

The closest way I have found to really "see" air is to jump through it. I ported for about 18 + years before I ever decided to skydive. Those 430+ jumps in the last 25 years didn't allow me to see air, but it gives me a better idea of what is happening in a port. What little nuances in finger/hand position and what clothing you wear will do to your entire body attitude and fall speed. Playing catch with a weighted ball in a breeze of 110+ mph gives you a far different perspective of what air is capable of. I have never thought of air and its mass in the same way since.
We all know that what a port sounds like at max flow is important to flow and quality, imagine being inside of a port and feeling and listening to what is going on around you. Porting, as life, is about perspective and perception. Anything that helps with that will be a big plus. 
Study: Boyle, Gay-Lussac, Hilsch, and Bernoulli for insights into air and its properties. You'll be miles ahead in the porting game, not just if you are a porter, but it will also allow you to better analyze ports when you look at them.      TIMINATOR

I like your skydiving illustration.

[K4FXD]

I wonder when, if it isn't already being done (probably Nascar or Pro Stock cars) someone will design a flow bench that has moving pistons and a camshaft to actuate the valves.

[Matt C]

That's been done, but CFD Simulations have pretty much made that "Potty mouth" obsolete.

[prodrag1320]

one thing ive found out a long time ago with porting is that a lot of stuff that looks real good & looks like it should flow great dosnt work as well as some stuff that looks like it shouldn't work at all

[Hossamania]

My heads were done back in '05, so I have a question, for you guys that have been doing this forever, have there been great improvements in headporting in the last 12 years, or is it possible my heads are about as good as they could be by today's standards?
In other words, is it possible that they are ported today as good as possible if the guy that did them was at the top of his game, back then and now? Or is it a given that knowledge in the field has leapt so far forward that there is no way they could possibly be as good as a modern head, castings being the same?

[thumper 823]

What static CR do you have ?

[Matt C]

My heads were done back in '05, so I have a question, for you guys that have been doing this forever, have there been great improvements in headporting in the last 12 years, or is it possible my heads are about as good as they could be by today's standards?
In other words, is it possible that they are ported today as good as possible if the guy that did them was at the top of his game, back then and now? Or is it a given that knowledge in the field has leapt so far forward that there is no way they could possibly be as good as a modern head, castings being the same?

If you got the same guy that did them back then, to do them now, they should be better. Maybe not allot
but everyone improves their game over time.

[thumper 823]

For me, Axtell reshaped the chambers for hi-dome pistons .
I run    HVY  two up most the time.
Twin plugged 10.5 CR
I also run an AFR gauge and have learned that dialing it in any other way is ..arrogant.
I used to think I could read plugs ...well you can, I can, BUt BUT but -
You can only read one test at a time .
One load range at a time , one RPM range at a time.
Very hard to do, and,  some think just pull the plug and look at it .
I will tell you this they are just reading the last couple minutes of what the plug was doing.
To see in the window the AFR is the best dam tool I have ever subscribed to!
Now you may wonder why i went off this direction.
A Higher CR is going to demand more fuel.
How much?
If your heads are like my heads they are just alike,..... but different.
There is not going to be a universal answer for which carb jet.
Perhaps close.
Close with ting ting is not a good thing.

[Hossamania]

My heads were done back in '05, so I have a question, for you guys that have been doing this forever, have there been great improvements in headporting in the last 12 years, or is it possible my heads are about as good as they could be by today's standards?
In other words, is it possible that they are ported today as good as possible if the guy that did them was at the top of his game, back then and now? Or is it a given that knowledge in the field has leapt so far forward that there is no way they could possibly be as good as a modern head, castings being the same?

If you got the same guy that did them back then, to do them now, they should be better. Maybe not allot
but everyone improves their game over time.

That was my thought too. I was just wondering if there was a technique(s) discovered that suddenly made 10 or 15 percent more power out of a head, all else being equal. Maybe even discovering that a slightly larger valve could be fit, along with different blending, and an "aha" moment, that has happened in the last ten years.
Maybe not relevant to this thread, sorry if that is so. I'm certainly not trying to waste anybody's time.

[thumper 823]

A proper port and valve job will allow a higher CR.
If you are getting 1.25 to 1 .33 per cube , you are doing real good by HD standards.

[build it]

A proper port and valve job will allow a higher CR.
If you are getting 1.25 to 1 .33 per cube , you are doing real good by HD standards.

Angled squish bands have their own troubles piston and combustion specific, respectively. I categorically agree that a good chamber and ports, along with other things, can tolerate more compression.

[thumper 823]

Glad you mentioned it.
Without pulling my paperwork I know i do have  .O30  squish.
I forget the angle.
This is one of the most important aspects of extracting TQ and HP.

[Matt C]

My heads were done back in '05, so I have a question, for you guys that have been doing this forever, have there been great improvements in headporting in the last 12 years, or is it possible my heads are about as good as they could be by today's standards?
In other words, is it possible that they are ported today as good as possible if the guy that did them was at the top of his game, back then and now? Or is it a given that knowledge in the field has leapt so far forward that there is no way they could possibly be as good as a modern head, castings being the same?

If you got the same guy that did them back then, to do them now, they should be better. Maybe not allot
but everyone improves their game over time.

That was my thought too. I was just wondering if there was a technique(s) discovered that suddenly made 10 or 15 percent more power out of a head, all else being equal. Maybe even discovering that a slightly larger valve could be fit, along with different blending, and an "aha" moment, that has happened in the last ten years.
Maybe not relevant to this thread, sorry if that is so. I'm certainly not trying to waste anybody's time.

(You're not wasting anyone's time, I may be, but that's not your problem. lol)

Anyway, It's not just about CFM. That's only a partial picture. The "quality" of flow, (velocity gradients
and fuel dispersion for example) need to be appreciated/considered.

We now have much better tools to model and see what's going on (where we had to use crude methods before).

For example, port mapping software lets you make graphical pictures of the port's air speeds at various lifts. This
stuff is just plain amazing, it's the closest thing to seeing the air.

The technology of today vs. just 10 years ago is so much more advanced. Weather we're talking about fuel
injection systems, measuring equipment or just raw computing power. The machines that we have at our
disposal right now are incredible.

Crunching the data to make a CFD model of an intake tract is no longer limited to universities and rich guys.
This stuff is more readily available and much less expensive now than even 5-8 years ago. We're living in
exciting times!

[kd]

Hoss, that's a carbed bike and one thing that was changing back then was intake port finish. The discussions on here indicate that carb intake carries fuel (as opposed to fuel injection at the head) and the polished intakes seemed to have pooling on the intake wall. Someone with more knowledge can confirm the problem (or slap me around  ). 

[Matt C]

Hoss, that's a carbed bike and one thing that was changing back then was intake port finish. The discussions on here indicate that carb intake carries fuel (as opposed to fuel injection at the head) and the polished intakes seemed to have pooling on the intake wall. Someone with more knowledge can confirm the problem (or slap me around  ). 

Absolutely correct. Polishing intake ports is a no-no.

[Hossamania]

Thanks for that, it's what I was looking for. Not necessarily an "aha" moment, but a bunch of little improvements that lead to significantly better performance.
And of course I understand that it always comes down to the combination of parts working with those heads. Improved heads on my combo may not really show up as any significant gains, as it cannot take advantage of the improved flow. So, it probably isn't going to be worth the time and money to drop new heads on mine, as the gains won't be significant enough to warrant it.
Now, if I squeeze it a little more, a more radical cam, a little bigger carb, I might be on to something...

[sfmichael]

Thanks for that, it's what I was looking for. Not necessarily an "aha" moment, but a bunch of little improvements that lead to significantly better performance.
And of course I understand that it always comes down to the combination of parts working with those heads. Improved heads on my combo may not really show up as any significant gains, as it cannot take advantage of the improved flow. So, it probably isn't going to be worth the time and money to drop new heads on mine, as the gains won't be significant enough to warrant it.
Now, if I squeeze it a little more, a more radical cam, a little bigger carb, I might be on to something...

nailed it

[thumper 823]

I asked what the CR is already. Even with better flowing heads, there is only so much BTU in given amount of gas.
you might improve the flow marginal.
Up the jet size marginally.
If you up the CR you will be able to add more gas and have more power. (up the jet size a couple numbers  )
it is a dawg chasing the tail thing.
We are never happy where we are at.
that's is why I shoot for the two-year tear dwn program.

[Matt C]

Adding more "gas" is not going to get you more power by itself. Doesn't work that way.

You have to figure a way to move more air through the engine along with that extra fuel.
That's the only way you're going to produce more BTUs.

[thumper 823]

True, but i thought that was a known factor.
One has to be somewhere in the ballpark of stoichiometric AFR
The AFR meter is the best thing I have ever invested in.

[Matt C]

  AFR meters are indispensable. I added them to my dyno stack even though I don't officially
"tune" bikes. Still nice to have... 

[Hossamania]

I asked what the CR is already. Even with better flowing heads, there is only so much BTU in given amount of gas.
you might improve the flow marginal.
Up the jet size marginally.
If you up the CR you will be able to add more gas and have more power. (up the jet size a couple numbers  )
it is a dawg chasing the tail thing.
We are never happy where we are at.
that's is why I shoot for the two-year tear dwn program.

If you were asking me what my CR is, I have no idea. This build was done long ago before I knew all the questions to ask. All I said to my trusted shop was, "I need to beat my friends." My heads were done by Eagle Jim, a local retired porter, 95" SE flattops, Andrews 55g cams. CCR is 175 currently on both cylinders with over 80,000 hard miles on this build. It still makes me happy.

[1workinman]

I asked what the CR is already. Even with better flowing heads, there is only so much BTU in given amount of gas.
you might improve the flow marginal.
Up the jet size marginally.
If you up the CR you will be able to add more gas and have more power. (up the jet size a couple numbers  )
it is a dawg chasing the tail thing.
We are never happy where we are at.
that's is why I shoot for the two-year tear dwn program.

If you were asking me what my CR is, I have no idea. This build was done long ago before I knew all the questions to ask. All I said to my trusted shop was, "I need to beat my friends." My heads were done by Eagle Jim, a local retired porter, 95" SE flattops, Andrews 55g cams. CCR is 175 currently on both cylinders with over 80,000 hard miles on this build. It still makes me happy.

Hoss I don't know a lot about Harley high performance engines , but I always thought that a really good set of head along with the supporting equipment would make better power with less compression and camshaft and carry further .  The reason I try to get good head work money well spent in my option

[Hossamania]

I agree on the headwork. I am the only one in my group of friends to do heads, and it is obvious every time we race. Fine by me.

[Matt C]

I agree on the headwork. I am the only one in my group of friends to do heads, and it is obvious every time we race. Fine by me.

Harley heads as they come from the factory are pretty lame.

[Matt C]

one thing ive found out a long time ago with porting is that a lot of stuff that looks real good & looks like it should flow great dosnt work as well as some stuff that looks like it shouldn't work at all

+1

Air goes where IT wants wants to go, not where you think it should go, (And it's counter-intuitive
most of the time).

That's why I laugh my ass off when I watch that guy on Youtube (tatro) port heads using his fingers
as a guide to where material should be removed. He doesn't believe in flowbenches! You can't make
this stuff up.

I could see where someone could develop the skills over time to "finger port", but never having used
a flowbench would make that very difficult to master.

"Ports don't need to look good, they just need to flow good" -Harold Bettes

[thumper 823]

I agree on the headwork. I am the only one in my group of friends to do heads, and it is obvious every time we race. Fine by me.

Harley heads as they come from the factory are pretty lame.

Harley head castings come with your motorcycle ready to be finished.
A Fresh  Evo can and should have .080 shave off it just to get it near the piston.
Freeeekin ridiculous.

[build it]

I agree on the headwork. I am the only one in my group of friends to do heads, and it is obvious every time we race. Fine by me.

Harley heads as they come from the factory are pretty lame.

Harley head castings come with your motorcycle ready to be finished.
A Fresh  Evo can and should have .080 shave off it just to get it near the piston.
Freeeekin ridiculous.

That's .080 less shortturn on a short turn limited application. Are you sure they should be cut .080?

Just a talking point, please read it as such.

I've got a set of b2s that're almost raw, I'm struggling to keep .040 on the deck. Came up with a plan but can't pop for the welding, yet. I'll tell you this much, the short turn will be at least .250 taller when I'm done with them.

[Matt C]

Making the s/s .250 taller should pay huge dividends. Well worth it, at least for experimental purposes.

That's the kind of stuff I like to do. Good luck!

 

[Don D]

Along the path we found that properly shaped domed pistons worked better in some of the CVO style chambers.
Reminiscent of the evolution of the BBC.

[Ohio HD]

The only thing that B2 heads and Evo heads have in common, is they're both heads. You can take 0.080" from an Evo head easy enough. Dealers used to take 0.050" off routinely when installing certain SE cams back when Evo was a current production motor.

[Don D]

I do this all the time on Evos and with minimal port work and an ev27 they make 85 squared. Happy owners for very low cost.

[thumper 823]

My info comes from Dave Mackie  and Larry over at Axtell
Dave said .050 is super EZ and should be done. And did it.
Then as I got deeper into this Atell reshaped the chambers and whacked a bunch more off.
(after remeasuring deck Ht and ECT,)
HD comes with .050 and more squish band if they have one, and not by mistake.
I am talking about virgin EVO heads.
Perhaps different years are better or worse.
The point being, without measuring this is a lot like using a yardstick with a large dose of presumption.
You can not bolt on Hp, and if you don't take the time to measure it all up
you are leaving more in the box on the table rather than in the engine.
All the pistons and cams in the world will not realize their full potential unless the whole install is done correctly.
Which is more than just aligning the index marks.

[Matt C]

Along the path we found that properly shaped domed pistons worked better in some of the CVO style chambers.
Reminiscent of the evolution of the BBC.

If you look at the most recent prostock/promod heads, the chambers are shallower, ports are taller, and valve-port angles are more favorable.

Shallower domes and smaller chambers improve flame travel, resist detonation and require less spark advance. (all good power making mods).

Both SB and BB heads have evolved along these lines.

The question is, will someone implement these developments/technology into Harley heads. Who knows?

[Don D]

Look at the b2 and b3 heads

[Matt C]

I've seen many b2/3 heads.

Problem is, we're pretty much limited to the architecture they've given us. We can't (easily) alter the port heights & angles of entry like the car guys can, so there's only so much we can do with what we have. ;/

[build it]

I've seen many b2/3 heads.

Problem is, we're pretty much limited to the architecture they've given us. We can't (easily) alter the port heights & angles of entry like the car guys can, so there's only so much we can do with what we have. ;/

Order them unfinished, then there's no difference.

[Matt C]

There has to be enough of a demand for someone to take that on.

[Don D]

My point is there are good castings.
And the hurricane is not a contender in my opinion. Too much work to fix the exhaust side.
Oh yeah remember that side..

[build it]

My point is there are good castings.
And the hurricane is not a contender in my opinion. Too much work to fix the exhaust side.
Oh yeah remember that side..

Is it noisey in stock form?

[Don D]

Not with the intake on 

[build it]

Not with the intake on 

I was referring to exhaust noise on the bench with or without a pipe? Or are you saying the exhaust quiets down with the intake on?

[Don D]

Yes, noisy all the way up

[build it]

Yes, noisy all the way up

With absolute certainty, that's not good.

[Don D]

Of course but in my case I was just flow testing. The fix is complex and expensive.
We, head porters et al, need to be able to roll with the punches and know how to fix the issues. That said sometimes the fixes are so time and labor intensive it puts the whole effort in question. Good news is there are head castings that are decent and don't need a huge amount of rework. So in this case the added airflow potential is good for nothing and actually can cause trouble like hard to tune.

[1workinman]

Of course but in my case I was just flow testing. The fix is complex and expensive.
We, head porters et al, need to be able to roll with the punches and know how to fix the issues. That said sometimes the fixes are so time and labor intensive it puts the whole effort in question. Good news is there are head castings that are decent and don't need a huge amount of rework. So in this case the added airflow potential is good for nothing and actually can cause trouble like hard to tune.

no doubt

[04 SE Deuce]

A hurricane after all is a turbulent storm.

[build it]

A hurricane after all is a turbulent storm.

Wise ass! LOL

[Unbalanced]

A hurricane after all is a turbulent storm.

Wise ass! LOL

Build it,  I thought you were done 4 pages ago LOL.         

Thanx !
The  Devil is in the details.
No production shop will ever treat your heads like their own.
Simple.
That is why I encourage everyone to buy a hard seat grinder and needed pilots /stones.
Used is cheap on eBay.
Do your own work and this will no longer baffle you.
Then, one is willing to try some other stuff. Like narrow short guides.
Its just no big deal along with whatever other tricks might be applied.

You're doing guide work first, correct?

I dig that you're using stones plenty to be said about that, all positive.

If you have a good foundation and principles no reason you can't go as far as you want to go. In my experience a lot of people especially on forums make port work sound like magic, it isn't, all it is is area scheduling.

That's my last post in this thread.

[build it]

Unbalanced, it happens.

[Unbalanced]

The B2's with just a little bit of clean up and setting of the squish obviously with all the right supporting cast, cam, pipe, and throttlebody and injectors 160 is in reach without stupid compression.     

[thumper 823]

No one would do seats first then the guides.
The trick is, and most shops even high-end ones,
will not take the time to get the new guide to relax in its new home..
All the work in the head is wasted if the guide moves at all.

[build it]

No one would do seats first then the guides.
The trick is, and most shops even high-end ones,
will not take the time to get the new guide to relax in its new home..
All the work in the head is wasted if the guide moves at all.

Aside from heating the head post install, what're you doing to get the guide to get it to relax.

[thumper 823]

To relax the heads for the long haul
There are some tricks I use and no secret.
  A man that does not know much will not share much.
I may miss a step as reflex habit abound here.
One, , always drill out the guide as much as you can to make it an EZ pull.
use a threaded puller rather than a driver.
Heat the head first B4 the extraction.
This way you do not need to OS the guide ..usually
I like dry ice and to hear the guides scream.
Literally.
try it.
Cryogenics is nothing new. A very tight guide to head fit helps cool the valve better.
You want the tightest fit posable without hurting the head.
Two,-
Next, you want to heat the head in the oven and install the cryogenic guide of your choice.
Dont use a beater to install them. Use a push or pull method.
Let cool, and heat a few times.
I do it six times with banging the heads on wood blocks as they cool.
I feel this makes everyone comfy for the long haul, plus we do this on out 911  engines.
It will not hurt anything and I am sure it helps.
We don't want the guide to move at all after it has been fitted for the valve, so it is all an insurance policy.
If it does it no longer will seat and be a leaker.
I would like to know how you guys do this also.

[1workinman]

To relax the heads for the long haul
There are some tricks I use and no secret.
  A man that does not know much will not share much.
I may miss a step as reflex habit abound here.
One, , always drill out the guide as much as you can to make it an EZ pull.
use a threaded puller rather than a driver.
Heat the head first B4 the extraction.
This way you do not need to OS the guide ..usually
I like dry ice and to hear the guides scream.
Literally.
try it.
Cryogenics is nothing new. A very tight guide to head fit helps cool the valve better.
You want the tightest fit posable without hurting the head.
Two,-
Next, you want to heat the head in the oven and install the cryogenic guide of your choice.
Dont use a beater to install them. Use a push or pull method.
Let cool, and heat a few times.
I do it six times with banging the heads on wood blocks as they cool.
I feel this makes everyone comfy for the long haul, plus we do this on out 911  engines.
It will not hurt anything and I am sure it helps.
We don't want the guide to move at all after it has been fitted for the valve, so it is all an insurance policy.
If it does it no longer will seat and be a leaker.
I would like to know how you guys do this also.

apples to pears I guess but I was watching a fellow on u tube go into some head work where he stated that some of the guys built a new engine ran in on the dyno for a while then pulled the heads down and reworked the heads as now the head have heat cycled and the valve seats would be concentric with the guides or I believe that is correct

[thumper 823]

That seems more OCD then needed...but to each their own...

[kd]

It sounds like that was a symptom of poor fitting (as in maybe worn) valve grinding tools or guides being changed and no follow up seat work?     There always will be some valve shake due to stem to guide fit tolerance so I don't really see what is to be gained if the initial work was done accurately.

[Don D]

What does this have to do with head flow and horsepower

[1workinman]

What does this have to do with head flow and horsepower

None I guess as I have not seen any suggestions on for example what is needed to make 150 hp in a 124 inch engine . I have an idea but only that 

[thumper 823]

What does this have to do with head flow and horsepower

None I guess as I have not seen any suggestions on for example what is needed to make 150 hp in a 124 inch engine . I have an idea but only that

Cyanide, suicide, and being cynical have the same results.
Tort comments for a thread that meanders is not  not such a bad thing.
There is a lot of merits and a whole bunch to be gleaned here.
For instance -you just aske about 150 Hp from a 124-inch engine.
That should be EZ as all you are asking for is 1.25 HP per cube.
That's pretty conservative in the big picture of things.
Crotch rockets and hitech engines produce way more  (@ a way higher RPM )
The devil is always in the details, and that part is the confluence of some math and some luck.
The tight guide to head assembly just talked about is a detail,
and a very good stem fit will help keep the hell created in there cool.
A proper cam, a fuel map generated and spark advance to follow it and the RPM up the scale should net you the results.
Once past the basics,  HP in most arenas cost 100 bucks per, its just a matter how much you want to spend.
With good heads ETC , 10.5/1 CR,  I am pretty sure you would be there.

[TJAH]

Is there a standard of how much HP you should be able to achieve given the amount of CFM your heads flow? Meaning, if your head flows 300CFM you can achieve (x) hp ci.

This was(?) Superflows formula. I could not find the document anymore from their site, https://www.superflow.com/

Potential hp = [0.256 x cfm @ 28 in. water] x no. of cylinders , at the crank.

I'm not saying that this is the whole truth, but should give you a ball park figure.
Propably the headporters here disagree, because none of the Superflow operators did bring this up ?

[N-gin]

There are some combos here that I've seen have 300 CFM put out 115 hp while others that top out at 270 CFM and lay down 170hp.

Like others say it is the whole picture, Dyno included.

Way too many variables.

[Don D]

 

[Barrett]

There are some combos here that I've seen have 300 CFM put out 115 hp while others that top out at 270 CFM and lay down 170hp.

Like others say it is the whole picture, Dyno included.

Way too many variables.

I do understand it's the whole package but I doubt 270CFM will get you 170HP.... Unless, it's a very happy dyno..

[rigidthumper]

Or a hair dryer attached to the intake

[build it]

To relax the heads for the long haul
There are some tricks I use and no secret.
  A man that does not know much will not share much.
I may miss a step as reflex habit abound here.
One, , always drill out the guide as much as you can to make it an EZ pull.
use a threaded puller rather than a driver.
Heat the head first B4 the extraction.
This way you do not need to OS the guide ..usually
I like dry ice and to hear the guides scream.
Literally.
try it.
Cryogenics is nothing new. A very tight guide to head fit helps cool the valve better.
You want the tightest fit posable without hurting the head.
Two,-
Next, you want to heat the head in the oven and install the cryogenic guide of your choice.
Dont use a beater to install them. Use a push or pull method.
Let cool, and heat a few times.
I do it six times with banging the heads on wood blocks as they cool.
I feel this makes everyone comfy for the long haul, plus we do this on out 911  engines.
It will not hurt anything and I am sure it helps.
We don't want the guide to move at all after it has been fitted for the valve, so it is all an insurance policy.
If it does it no longer will seat and be a leaker.
I would like to know how you guys do this also.

Good practices Thumper. I'll only install guides and seats with liquid nitrogen in my own stuff. I have 3 sets of moldstar 90 seats for some raw b2s thatre just itching to get touched, 2.300" intakes, 1.700" exhaust valves. I wanted to run a 2.350" or bigger intake, and a 1.600 or smaller exhaust but someone I know personally with a lot of experience with UPM heads didn't like it at all; I respect this guy, he's a mentor and a friend.

OHC or block machine aside, where a torque plate is necessary for most procedures, and unbolting the plate, letting the work return to room temp and retorquing at each successive step is absolutely necessary; I'm not seeing much "binding" necessitating a "relaxing" process. That includes extreme duty max effort two valve applications.

Now, if serious welding is part of the program, particularly around the seats or guides, I have a different opinion. In that case, first, I machine shy of where I want to end up, and expect it to run like "Potty mouth". I might even use a single angle cutter for a seat to come in and leave all else alone (talking about seats only). I'd run the engine for 500-1000 miles and tear it down for inspection. The goal here would be adequate heat cycles for the probable but not inevitable movement to take place. Then I'd tear everything down, inspect, measure, final machine, and measure again.

If you keep pushing I think you'll achieve a level of performance higher than you expect.

[thumper 823]

Hay !
I am glad someone agrees with a way to do this! LOL
After studying Metallurgy for a whilst  (welding school about 40 years ago ) LOL
One quickly learns there is much to be learned.
There is no end.
There is no end, to the little details that make the difference between satisfactory and excellent.
I have not ever tried welding up my heads ..yet.
You have me there.
Raised ports are looking like another interesting project.

[build it]

Hay !
I am glad someone agrees with a way to do this! LOL
After studying Metallurgy for a whilst  (welding school about 40 years ago ) LOL
One quickly learns there is much to be learned.
There is no end.
There is no end, to the little details that make the difference between satisfactory and excellent.
I have not ever tried welding up my heads ..yet.
You have me there.
Raised ports are looking like another interesting project.

There're some very interesting things you can do with welded heads, flow, spring, chamber, valve train wise, and still fit in an OE frame. No one will like it though because it's based on efficiency and not that atypical bulk cube approach.

[Don D]

There are some combos here that I've seen have 300 CFM put out 115 hp while others that top out at 270 CFM and lay down 170hp.

Like others say it is the whole picture, Dyno included.

Way too many variables.

I do understand it's the whole package but I doubt 270CFM will get you 170HP.... Unless, it's a very happy dyno..

Tounge in cheek.
Agree on that too a bit of an exaggerated statement but I get his point

[thumper 823]

Hay !
I am glad someone agrees with a way to do this! LOL
After studying Metallurgy for a whilst  (welding school about 40 years ago ) LOL
One quickly learns there is much to be learned.
There is no end.
There is no end, to the little details that make the difference between satisfactory and excellent.
I have not ever tried welding up my heads ..yet.
You have me there.
Raised ports are looking like another interesting project.

There're some very interesting things you can do with welded heads, flow, spring, chamber, valve train wise, and still fit in an OE frame. No one will like it though because it's based on efficiency and not that atypical bulk cube approach.

I would love to see some pics  of your work.!
I will warn you,
iI I like them I will steal your ideas! LOL
Like I said my heads are off right now ....Between Sturgis overhaul.

[build it]

Thumper, as I said earlier it will be a while before I can afford the welding. It could be a few months or more, but I'll gladly send some progress pics once I put chips on the floor. I'm just wrapping up an education in high performance, and looking for work in the field with either strong leadership or a low hourly rate and a lot of hours. FWIW, whatever I send will be backed up by cold hard data, nothing else.

[thumper 823]

I tried to PM you..
My Nephew tigs, we are both gearheads.
I know I can get him to fill what you want for nothing.
He just needs to know where and how much.

[build it]

I tried to PM you..
My Nephew tigs, we are both gearheads.
I know I can get him to fill what you want for nothing.
He just needs to know where and how much.

Thank you for the generous offer, but I have to pass. I've got enough scratch to get me where I need to go in 3 weeks, buy a tent, and get a storage unit. It's looking like Florida, Indy, or possibly Phoenix; I prefer the second two but originally planned on being further west or the Carolinas. Not many shops hiring, so we'll see how it turns out. I give you my word that I'll update you the second I make progress.

[N-gin]

There are some combos here that I've seen have 300 CFM put out 115 hp while others that top out at 270 CFM and lay down 170hp.

Like others say it is the whole picture, Dyno included.

Way too many variables.

I do understand it's the whole package but I doubt 270CFM will get you 170HP.... Unless, it's a very happy dyno..

sorry  150 hp!

http://harleytechtalk.com/htt/index.php?topic=91480.0

[thumper 823]

There ya go 1.36 per cube .
A very doable number,

[1FSTRK]

So we have an higher rpm, street strip 110 ci example of 1.36 HP/CI with .545 HP/CFM.

[Johnwesley]

Oops

Wrong thread

[1FSTRK]

There are some combos here that I've seen have 300 CFM put out 115 hp while others that top out at 270 CFM and lay down 170hp.

Like others say it is the whole picture, Dyno included.

Way too many variables.

I do understand it's the whole package but I doubt 270CFM will get you 170HP.... Unless, it's a very happy dyno..

sorry  150 hp!

http://harleytechtalk.com/htt/index.php?topic=91480.0

N-gin you get the concept. A 110 CI making 150hp is 1.36 HP/CI and the heads flow about 282cfm so we are at .531 HP/CFM
Once we have examples of what is possible we can look at what is going on with similar combos that do not produce as well. The happy dyno and flow bench BS is always brought up but really is just a diversion from the subject . If you gather large data samples (like we have here on HTT) you can always disregard the very top and very bottom numbers and still have plenty of usable data to draw from when looking for trends. You also can only draw so much from programs and info gathered from autos or any other types of engines because of the unique design of the HD V-twin engine. Your not going to get a formula that spits out the HP of an engine just by plugging in the cfm number of the head from a flow bench. What you can get is an idea of what should be possible from a given CI V-twin engine of the HD design with a head that flows X cfm and when the engine comes up short you know something is wrong and you need to find out what. This is the very basis for questioning the performance of the M-8's. They have flow but as a group the power is not on par with other HD engines when you compare similar stages of builds using the hp/cfm numbers.

[thumper 823]

There are some combos here that I've seen have 300 CFM put out 115 hp while others that top out at 270 CFM and lay down 170hp.

Like others say it is the whole picture, Dyno included.

Way too many variables.

I do understand it's the whole package but I doubt 270CFM will get you 170HP.... Unless, it's a very happy dyno..

sorry  150 hp!

http://harleytechtalk.com/htt/index.php?topic=91480.0

N-gin you get the concept. A 110 CI making 150hp is 1.36 HP/CI and the heads flow about 282cfm so we are at .531 HP/CFM
Once we have examples of what is possible we can look at what is going on with similar combos that do not produce as well. The happy dyno and flow bench BS is always brought up but really is just a diversion from the subject . If you gather large data samples (like we have here on HTT) you can always disregard the very top and very bottom numbers and still have plenty of usable data to draw from when looking for trends. You also can only draw so much from programs and info gathered from autos or any other types of engines because of the unique design of the HD V-twin engine. Your not going to get a formula that spits out the HP of an engine just by plugging in the cfm number of the head from a flow bench. What you can get is an idea of what should be possible from a given CI V-twin engine of the HD design with a head that flows X cfm and when the engine comes up short you know something is wrong and you need to find out what. This is the very basis for questioning the performance of the M-8's. They have flow but as a group the power is not on par with other HD engines when you compare similar stages of builds using the hp/cfm numbers.

I have to give that 5  STAR paragraph.
There are a lot of problems depending just on a flow bench.
For every different cam ,and every different cam event, and piston position  in the bore,   a plethora of numbers arises that none has time to chase.

[Don D]

N-gin
There are some fundamental reasons why there are some excellent producers and some not so great. Airflow potential on the intake side is yet again just one data point out of the context of the whole build combination. Many, but not all, of the builds that drop like a rock after 5k are being screwed up by problems on the exhaust side which then has bad effects during overlap. The head can and is sometimes related to the issue but the pipe is usually the culprit along with a cam that doesn't cooperate and help and sometimes flat out gets in the way. When these big builds fall flat at WOT full rpm under load you will also see the MAP pressure that started at 100kpa (sea level) start to taper back when they enter the problem area.
Comes back to the method used to design the build again.
Standard logic..
Good pipe + good cam + good heads + good throttle body + good tune= good combination
There are a half dozen or so reasons why that method sucks and many times ends up with disappointing results.

A better logical approach..
A good combination of parts properly installed, rings broken in (ring seal, low blowby), and tuned right = good combination

Heads are part of that combination and play their part but remember the barn door wide open in the front all the time doesn't do squat for airflow if the back door is closed or the back door is wide open and the front door closed.

On another topic, side note, I am impressed with the results we are seeing with the M8 motor and see high aggregate torque available with simple stage 2 changes. That makes riders happy. Now they need to get the sumping fixed, a bigger issue then how to get these to run.

[1FSTRK]

Don as always many good points, maybe too many. The thread on how to build a performance HD engine could get a little long and wander a bit. To eat this elephant one bite at a time we can use things like the intake flow or any other part of the mix to set very general guide lines. For a 103 with a TR590 cam we know that 185cfm would be lacking and 350cfm would likely be coming through to big a valve and port, so looking at any combo we have to look at the pieces. On the other end if we see a know engine combo that is not working up to par and everything else is spot on can we not look to the heads from an unknown vendor that flow 30% to much air for the power being made? would we be wrong to question the valve size, port size, velocity, and so on of the head, remember we are dealing with a tried and true combo.

[Don D]

If separating out and examining only intake (not my suggestion but for discussion purposes) you could also say that 150 FPS is too slow and 600 is too high port speed. If you know the cross-sectional area of a port you can calculate the port velocity based on the cylinder diameter and the piston speed at any given RPM. This matters too and the soggy reversion laden example is one precipitate of improper head sizing, too big of a barn door. The result is again falling flat at high rpm. Cams can only crutch this. Better to get it right first.

[1FSTRK]

Let us approach this from a different angle. Here is the OP's question.

Is there a standard of how much HP you should be able to achieve given the amount of CFM your heads flow? Meaning, if your head flows 300CFM you can achieve (x) hp ci.

Now doesn't every engine sim program ask for head flow to be input?
The question isn't "can head flow alone predict the hp of an engine"
The part in red is covering all the other variables that you will have to get right to "achieve" the power potential of the flow and velocity is one of them just like compression, cam timing, and all the others.