Author Topic: offset valve seat flow numbers  (Read 1993 times)

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Offline sbcharlie

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offset valve seat flow numbers
« on: November 23, 2017, 05:40:41 AM »
i used a 2006 twin cam head for flow test
i offset the intake seat at the push rod side at .030
intake    stock               offset
.100     60                     62
.200     124                   130
.300     175                   178
.400     209                 215
.500    214                  230
.600    213                  234

no port work  89% throat ratio  standard oem valves

Offline 1FSTRK

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Re: offset valve seat flow numbers
« Reply #1 on: November 23, 2017, 05:47:10 AM »
But the angle cut that the valve contacts is the actual seat, everything else is port work regardless of what you use to machine it.

Offline sbcharlie

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Re: offset valve seat flow numbers
« Reply #2 on: November 23, 2017, 05:50:58 AM »
the angles are altered below the contact valve angle, i have a u-tube  that shows how this done, its listed as offset valve seat fixture..   interesting way to enhance air flow

Offline Admiral Akbar

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Re: offset valve seat flow numbers
« Reply #3 on: November 23, 2017, 06:38:46 AM »
i used a 2006 twin cam head for flow test
i offset the intake seat at the push rod side at .030
intake    stock               offset
.100     60                     62
.200     124                   130
.300     175                   178
.400     209                 215
.500    214                  230
.600    213                  234

no port work  89% throat ratio  standard oem valves

You changed the throat ratio to 91% when you bored out the seat.

So how does it compare to boring the seat throat out 0.030 on center?

Offline sbcharlie

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Re: offset valve seat flow numbers
« Reply #4 on: November 23, 2017, 06:48:42 AM »
it has a 89 % throat ratio . 

Offline sbcharlie

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Re: offset valve seat flow numbers
« Reply #5 on: November 23, 2017, 06:50:45 AM »
i going to have to shoot another video to try and explain this, the bottom line it enhances air flow.

Offline Matt C

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Re: offset valve seat flow numbers
« Reply #6 on: November 23, 2017, 07:26:21 AM »
I saw that video Charlie, pretty cool. (Always more than one way to skin a cat)
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Offline sbcharlie

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Re: offset valve seat flow numbers
« Reply #7 on: November 23, 2017, 08:05:43 AM »
darin Morgan  was impressed , to me, he  is  the guy in cylinder design.

Offline Admiral Akbar

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Re: offset valve seat flow numbers
« Reply #8 on: November 23, 2017, 12:38:41 PM »
it has a 89 % throat ratio .

Why don you give us some actual numbers....   IIRC the intake valve is 1.8 and the stock throat is 1.625.. What is the throat diameter after offset bore?

Corrected..
My mistake
« Last Edit: November 23, 2017, 06:12:31 PM by Admiral Akbar »

Offline gordonr

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Re: offset valve seat flow numbers
« Reply #9 on: November 23, 2017, 01:42:50 PM »
 Interesting sb. Did your "offset oval" workout with the same % increase in your high performance head work?
"If was easy everyone would do it"

Offline Matt C

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Re: offset valve seat flow numbers
« Reply #10 on: November 23, 2017, 02:12:03 PM »
darin Morgan  was impressed , to me, he  is  the guy in cylinder design.

Yep. he's the man
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Offline sbcharlie

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Re: offset valve seat flow numbers
« Reply #11 on: November 23, 2017, 02:56:14 PM »
What part of stock Cylinderhead that you do not understand
The test was with a 1.800 intake valve.  If a 1.900 flowed that low
It would be a safety ported head

Offline 04 SE DEUCE

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Re: offset valve seat flow numbers
« Reply #12 on: November 23, 2017, 03:31:57 PM »
I think he is assuming that you are modifying the throat,  not just the angle/s cut below the seat angle.

Offline HD Street Performance

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Re: offset valve seat flow numbers
« Reply #13 on: November 23, 2017, 06:11:02 PM »
The stock throat and stock valve are 90%.
If you move over you will end up with an oval throat, any way it's diced or sliced you got to get bigger than 90.
Not bashing just not understanding.

Offline Admiral Akbar

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Re: offset valve seat flow numbers
« Reply #14 on: November 23, 2017, 06:18:13 PM »
What part of stock Cylinderhead that you do not understand
The test was with a 1.800 intake valve.  If a 1.900 flowed that low
It would be a safety ported head

My mistake on valve size 1.8...   If the stock throat to value is 89% and you bore out the seat 0.030. How can it still be 89%?  Looked a your video and you look to be boring out the throat with an offset.. Hole is still bigger. Isn't the percent you are talking about, throat ID to valve OD?  Or is it something else?

Offline sbcharlie

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Re: offset valve seat flow numbers
« Reply #15 on: November 24, 2017, 06:31:08 AM »
sorry for some confusion, in the video we are installing a 1.900 intake valve, plus i am offset the seat angles at the 12 oclock position . on the flow numbers i posted, its for a stock head. i want to note the angle on the offset is 82 degree .  i going to try and get a better video on this operation. think about the angle of 82 degree the start point with .030 offset will not touch the throat ratio. I'm seeing on twin cam and other heads  the 3or 9 o'clock position works better. its a new learning process. today will be working with a Serdi machine with this fixture. my thoughts a form tool machine will be a lot easier to offset seat angles   sbc

Offline Admiral Akbar

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Re: offset valve seat flow numbers
« Reply #16 on: November 24, 2017, 07:48:58 AM »
sorry for some confusion, in the video we are installing a 1.900 intake valve, plus i am offset the seat angles at the 12 oclock position . on the flow numbers i posted, its for a stock head. i want to note the angle on the offset is 82 degree .  i going to try and get a better video on this operation. think about the angle of 82 degree the start point with .030 offset will not touch the throat ratio. I'm seeing on twin cam and other heads  the 3or 9 o'clock position works better. its a new learning process. today will be working with a Serdi machine with this fixture. my thoughts a form tool machine will be a lot easier to offset seat angles   sbc

A little more clarification would be helpful..   When you say you are offsetting the tool 82 degrees, is a 82 degree form tool or are you tilting the head another 8 degrees?     Have you measured the throat afterwards?

Offline HD Street Performance

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Re: offset valve seat flow numbers
« Reply #17 on: November 24, 2017, 08:36:29 AM »
1.6251.805 = .900
With an 82deg form tool offset .030 in the x direction the bottom of the seat ring would still be unchanged so it remains at 90%.
The angle is in essence just a one sided bowl hawg below the bottom seat angle from what I understand.  :slap:
« Last Edit: November 24, 2017, 09:31:25 AM by HD Street Performance »

Offline Admiral Akbar

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Re: offset valve seat flow numbers
« Reply #18 on: November 24, 2017, 09:00:15 AM »
1.6251.805 = .900
With an 82deg form tool offset .030 in the x direction the bottom of the seat ring would still be unchanged so it remains at 90%.
The angle is in essence just a one sided hole hawg below the bottom seat angle from what I understand.  :slap:

That makes sense..   Sine(8deg) * 0.25" (seat height) = 0.035"  Adjust the cut depth and the lower edge for the seat (part of the throat) is untouched.  Still wonder if the offset is needed.. How does the seat flow with the same cut and no offset? 

Offline wfolarry

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Re: offset valve seat flow numbers
« Reply #19 on: November 24, 2017, 11:39:48 AM »
If you want to see if it works set it up on your milling machine & you can do the same thing.
I've seen guys do this with car heads where they wanted to open up the throat but didn't want to hit water.

Offline Matt C

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Re: offset valve seat flow numbers
« Reply #20 on: November 24, 2017, 11:59:47 AM »
1.6251.805 = .900
With an 82deg form tool offset .030 in the x direction the bottom of the seat ring would still be unchanged so it remains at 90%.
The angle is in essence just a one sided hole hawg below the bottom seat angle from what I understand.  :slap:

That makes sense..   Sine(8deg) * 0.25" (seat height) = 0.035"  Adjust the cut depth and the lower edge for the seat (part of the throat) is untouched.  Still wonder if the offset is needed.. How does the seat flow with the same cut and no offset?

Now my curiosity is kicking up; I'm going to test a stock head in the coming days.

No fancy offset stuff, just a stock head, then put a really good seat profile on it, then same head with a better valve and
matching 90% throat. I might even hit the short side with a little loving. I want to see what a stock head with minimal
work can achieve.

I'll post the graphs on my FB page.
« Last Edit: November 24, 2017, 12:13:52 PM by MCE Performance »
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Offline HD Street Performance

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Re: offset valve seat flow numbers
« Reply #21 on: November 24, 2017, 12:35:31 PM »
Keep the test clean, first no short turn work just seat, no back cuts. Then move forward one step at a time to show the progression,  would be my approach.

Offline Matt C

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Re: offset valve seat flow numbers
« Reply #22 on: November 24, 2017, 12:59:18 PM »
That's the plan.

(wouldn't be worth shit otherwise)
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Offline Timinator

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Re: offset valve seat flow numbers
« Reply #23 on: November 25, 2017, 07:22:06 PM »
OK. If I understand what's happening here, the seat remains the same, and the lower angle cuts below the seat are set to favor some other angle toward the port. Correct? If this is what we are discussing, you folks haven't installed smaller  ID seats and hand ported from the lower seat cut to the port angle? I thought that's how we all do it? What am I missing here? Why do it with a separate setup, when you are in there porting anyway? I have also experimented with lathe profiling the lower portion of a smaller diameter, taller seat before installation so as to create a venture below the seat before porting. Am I all wet here? Help!!!!   TIMINATOR
MODESTY IS A CRUTCH FOR THE INCOMPETENT!!!

Offline 1FSTRK

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Re: offset valve seat flow numbers
« Reply #24 on: November 25, 2017, 07:56:29 PM »
OK. If I understand what's happening here, the seat remains the same, and the lower angle cuts below the seat are set to favor some other angle toward the port. Correct? If this is what we are discussing, you folks haven't installed smaller  ID seats and hand ported from the lower seat cut to the port angle? I thought that's how we all do it? What am I missing here? Why do it with a separate setup, when you are in there porting anyway? I have also experimented with lathe profiling the lower portion of a smaller diameter, taller seat before installation so as to create a venture below the seat before porting. Am I all wet here? Help!!!!   TIMINATOR

Many buy a seat cutting machine and hold to the belief that the work done on them as delivered is the holy grail and must never be touched. I have been told more than once you can mess around in the port or chamber just do not touch that valve seat area it was cut on the machine. Fortunately some years back I found a guy that knew better.

Offline wfolarry

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Re: offset valve seat flow numbers
« Reply #25 on: November 26, 2017, 05:38:40 AM »
There was a company selling valve seats with a radius on the bottom with claims of big flow gains some years back. Some people believed it. The guys that actually ported heads knew better. If you're making changes & flow testing the changes you're on the right path. If you make changes without testing then you're missing the whole point.

There are some big name companies out there that would be better off leaving the seat as it was instead of blending it all in & killing the flow. There's a right way & a wrong way for everything. You'd be surprised how many heads I fix with nothing more than a valve job.

Offline 1FSTRK

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Re: offset valve seat flow numbers
« Reply #26 on: November 26, 2017, 06:20:12 AM »
There was a company selling valve seats with a radius on the bottom with claims of big flow gains some years back. Some people believed it. The guys that actually ported heads knew better. If you're making changes & flow testing the changes you're on the right path. If you make changes without testing then you're missing the whole point.

There are some big name companies out there that would be better off leaving the seat as it was instead of blending it all in & killing the flow. There's a right way & a wrong way for everything. You'd be surprised how many heads I fix with nothing more than a valve job.

Add the final step of confirming the new found flow actually makes more power in the intended rpm either with a proper dyno comparison or at a timed track and I am with you 100%.

Offline Timinator

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Re: offset valve seat flow numbers
« Reply #27 on: November 26, 2017, 06:26:48 AM »
If adding a venturi in the seat ring below the seat worked, I'd be doing it. On a few heads it was a Band-Aid and did provide small gains, but not on decent heads to begin with. Anything current is better than that. In the old days, we did such things to Class racing drag cars, until the NHRA made a standardized valve job mandatory. That act stifled innovation, except in the Pro classes, at least until aftermarket heads flooded the scene.
Myself, my SF-600, and my Dyno Jet 250 work as a team, its a good team. But I try everything that I can think of and anything hinted at or suggested to effect improvements. Its an ongoing thing, sometimes its even fun, no, make that interesting.
Present thread not included, sometimes I have no idea where some of the stuff I read about comes from. I read the ads, go to the trade shows and look at stuff and I know that if the guy selling it had a brain, or a Dyno, he'd have kept his mouth shut and his advertising cash in his pocket!
As for the Pros everywhere, most of them  keep the good stuff to themselves.
David Vizard told me 30 years ago that any info in an article written by him was 3-5 years old, and anything in his books was 5-10 years old, he stays that far ahead of the pack. Engineers and companies pay him for the latest info, that, he doesn't give away. The old info is cheap, or free, because it is old info. Carry on!    TIMINATOR
MODESTY IS A CRUTCH FOR THE INCOMPETENT!!!

Offline Matt C

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Re: offset valve seat flow numbers
« Reply #28 on: November 26, 2017, 07:00:30 AM »
If adding a venturi in the seat ring below the seat worked, I'd be doing it. On a few heads it was a Band-Aid and did provide small gains, but not on decent heads to begin with. Anything current is better than that. In the old days, we did such things to Class racing drag cars, until the NHRA made a standardized valve job mandatory. That act stifled innovation, except in the Pro classes, at least until aftermarket heads flooded the scene.
Myself, my SF-600, and my Dyno Jet 250 work as a team, its a good team. But I try everything that I can think of and anything hinted at or suggested to effect improvements. Its an ongoing thing, sometimes its even fun, no, make that interesting.
Present thread not included, sometimes I have no idea where some of the stuff I read about comes from. I read the ads, go to the trade shows and look at stuff and I know that if the guy selling it had a brain, or a Dyno, he'd have kept his mouth shut and his advertising cash in his pocket!
As for the Pros everywhere, most of them  keep the good stuff to themselves.
David Vizard told me 30 years ago that any info in an article written by him was 3-5 years old, and anything in his books was 5-10 years old, he stays that far ahead of the pack. Engineers and companies pay him for the latest info, that, he doesn't give away. The old info is cheap, or free, because it is old info. Carry on!    TIMINATOR

Ha ha ha...  :agree:

Those that can do, do. (And keep secrets close to the vest). The exception to that is Darin, I went through
his program, and he showed me everything and anything I wanted to see. 
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Offline Timinator

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Re: offset valve seat flow numbers
« Reply #29 on: November 26, 2017, 06:29:50 PM »
Smaller diameter than normal seat, deeper too. Machine portend with a forming tool in lathe before installation. Now you could also do the venturi or offset seat planform with a single point seat cutter machine or CNC. Just do one and trace it!  I'm in Avondale,AZ. mebbie I'll stop in...  TIMINATOR
MODESTY IS A CRUTCH FOR THE INCOMPETENT!!!

Offline sbcharlie

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Re: offset valve seat flow numbers
« Reply #30 on: November 27, 2017, 03:46:36 AM »
come over i would like to meet you. sbc

Offline PanHeadRed

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Re: offset valve seat flow numbers
« Reply #31 on: November 29, 2017, 05:01:06 AM »
i used a 2006 twin cam head for flow test
i offset the intake seat at the push rod side at .030
intake    stock               offset
.100     60                     62
.200     124                   130
.300     175                   178
.400     209                 215
.500    214                  230
.600    213                  234

no port work  89% throat ratio  standard oem valves

Impressive that it does not stall after .4"

Offline HD Street Performance

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Re: offset valve seat flow numbers
« Reply #32 on: November 29, 2017, 05:35:31 PM »
I tested a stock head, cleaned, stock guides and OEM valve job
.100 66.7
.200 123.5      
.300 187.9      
.400 220.8      
.500 227.1      
.600 225.0

I then did a valve job 5 angles in and 3 + radius ex, protrusion set to 2.030 all, no back cuts stock re-faced valves 45 seats
.100 65.3      
.200 127.5      
.300 189.3      
.400 229.2      
.500 237.5      
.600 241.7

63F, 1.7 x 2" Inlet velocity stack. 3.937 bore, 08 Mercury casting
Saenz 600 Bench calibrated with PTS plates

Offline Matt C

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Re: offset valve seat flow numbers
« Reply #33 on: November 29, 2017, 06:00:57 PM »
Was the sparkplug in?
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Offline 1FSTRK

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Re: offset valve seat flow numbers
« Reply #34 on: November 30, 2017, 04:15:38 AM »
I tested a stock head, cleaned, stock guides and OEM valve job
.100 66.7
.200 123.5      
.300 187.9      
.400 220.8      
.500 227.1      
.600 225.0

I then did a valve job 5 angles in and 3 + radius ex, protrusion set to 2.030 all, no back cuts stock re-faced valves 45 seats
.100 65.3      
.200 127.5      
.300 189.3      
.400 229.2      
.500 237.5      
.600 241.7

63F, 1.7 x 2" Inlet velocity stack. 3.937 bore, 08 Mercury casting
Saenz 600 Bench calibrated with PTS plates

Did you offset any of the angle cuts?

Offline HD Street Performance

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Re: offset valve seat flow numbers
« Reply #35 on: November 30, 2017, 05:27:05 AM »
Nothing more than what I stated. No cuts below a Serdi form tool valve job

Offline 1FSTRK

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Re: offset valve seat flow numbers
« Reply #36 on: November 30, 2017, 11:28:54 AM »
Nothing more than what I stated. No cuts below a Serdi form tool valve job

Ok, for some reason I thought you were testing the before and after offset results for yourself.
Not sure what your post has to do with this thread  :scratch:

Offline HD Street Performance

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Re: offset valve seat flow numbers
« Reply #37 on: November 30, 2017, 12:50:18 PM »
My own interest and to compare what influence a proper valve job has on the mix. I am sure there is a very nice valve job that is accompanied with those offset seats. I just wondered what the stock heads did with a centered seat plus or minus and I had some jobs in the shop already to test this.

Offline 1FSTRK

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Re: offset valve seat flow numbers
« Reply #38 on: November 30, 2017, 01:18:37 PM »
My own interest and to compare what influence a proper valve job has on the mix. I am sure there is a very nice valve job that is accompanied with those offset seats. I just wondered what the stock heads did with a centered seat plus or minus and I had some jobs in the shop already to test this.


And you post it here. Do you really feel it has any relevance ?
To compare you need to now offset the seat with your valve job and flow test on your bench with your inlet flange.
 

Offline HD Street Performance

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Re: offset valve seat flow numbers
« Reply #39 on: November 30, 2017, 01:20:01 PM »
Ok

Online kd

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Re: offset valve seat flow numbers
« Reply #40 on: November 30, 2017, 01:33:11 PM »
i used a 2006 twin cam head for flow test
i offset the intake seat at the push rod side at .030
intake    stock               offset
.100     60                     62
.200     124                   130
.300     175                   178
.400     209                 215
.500    214                  230
.600    213                  234

no port work  89% throat ratio  standard oem valves


I tested a stock head, cleaned, stock guides and OEM valve job
.100 66.7
.200 123.5      
.300 187.9      
.400 220.8      
.500 227.1      
.600 225.0

I then did a valve job 5 angles in and 3 + radius ex, protrusion set to 2.030 all, no back cuts stock re-faced valves 45 seats
.100 65.3      
.200 127.5      
.300 189.3      
.400 229.2      
.500 237.5      
.600 241.7

63F, 1.7 x 2" Inlet velocity stack. 3.937 bore, 08 Mercury casting
Saenz 600 Bench calibrated with PTS plates



I want to qualify my observation by stating I do not see this as a competition but use the expression "race" in my statement to make a point. 

Without knowing if the CBC head first had a "good' multi angle valve job before the offset cut and numbers were posted makes it tough to compare the value of the offset work. It appears to me at least that when you compare the steps in the flow test there is not enough difference between the two to call the "race" on. I would guess each set of similar heads getting a similar valve job would have a variance of plus or minus what we see between the CBC offset head and Don's head. Similarly the variance between the two we now have for comparison are so close that I would call a draw. Now, if the CBC head did not have the benefit of a good and similar valve job, but was given one and then after the offset treatment gained more, we may have evidence of a procedure that has something to offer. This would be contingent on repeatability on both counts.  Good stuff guys but I think we need more evidence to show real change and the ability to repeat the gains. Have at er. 
KD

Offline 1FSTRK

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Re: offset valve seat flow numbers
« Reply #41 on: November 30, 2017, 01:50:17 PM »
I agree that at this point neither set of tests mean much.
I have seen that offsetting the the cuts both above and below the seat cut does make a difference on many heads but the direction you need to go and the amount of difference it makes will vary with head and port design. It can be enough that over the years many race sanctions with stock classes have added rules stating all valve seat cuts must be concentric. Moving cuts below the seat can effectively alter the short and long side radius of the port in one of the most important parts of the intake tract.

One other other thing to remember is the precision with which HD casts these heads, the ports are all over the place with core shift so that along will alter the results from head to head.
This is not a game changer on otherwise stock heads but on a proven port design if researched properly it can provide consistant gains.

Offline TorQuePimp

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Re: offset valve seat flow numbers
« Reply #42 on: November 30, 2017, 03:00:58 PM »
Run a CNC program on two rear or two front heads along with the chamber that cleans up 100%
One valve job normal.....one offset
Pretty simple

Offline jsachs1

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Re: offset valve seat flow numbers
« Reply #43 on: November 30, 2017, 03:10:17 PM »
Run a CNC program on two rear or two front heads along with the chamber that cleans up 100%
One valve job normal.....one offset
Pretty simple
The proper way to analyze.  :up:
John

Offline Matt C

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Re: offset valve seat flow numbers
« Reply #44 on: November 30, 2017, 03:45:34 PM »
Hot damn! Now that's the best idea I hurd so far. That wood put it to rest.
Life is like a roll of TP. The closer you get to the end the faster it goes.

Offline Ohio HD

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Re: offset valve seat flow numbers
« Reply #45 on: November 30, 2017, 04:00:48 PM »
Run a CNC program on two rear or two front heads along with the chamber that cleans up 100%
One valve job normal.....one offset
Pretty simple

Empirical data       :up:

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Offline 1FSTRK

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Re: offset valve seat flow numbers
« Reply #46 on: November 30, 2017, 04:46:54 PM »
CNC is definitely the way to go in todays world but back in the days I witnessed this testing it was done by porting a head and flow testing to achieve the best result then the seat was removed and a new test seat was installed and cut and flow tested. This test seat replacement was performed several times until the best offset was achieved then actual permanent seats were installed, cut, then dyno tested.

Offline Timinator

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Re: offset valve seat flow numbers
« Reply #47 on: November 30, 2017, 06:07:40 PM »
Even CNC machined ports can vary, you would still have to flow test them first to make sure they are of the same flow, or the test goes out the window. Still I believe flow guides are a lousy way to test a head flow. Air can flow 360 degrees around the inlet guide, but with the T-Body and intake it must follow what is actually being used to supply the air. I believe that the port MUST BE ported differently with a manifold and T-body attached to get the best results. That's why we do it that way. I also believe there is more difference in porting with a manifold and the brand T-body actually used, than an offset seat alone can provide, you should actually do both. I also believe that the offset would be different from a guide to a manifold/ T-body. If you want to be the best, you need to do the most. Let the s**t storm continue....    JMHO  TIMINATOR
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Offline 1FSTRK

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Re: offset valve seat flow numbers
« Reply #48 on: November 30, 2017, 06:13:19 PM »
Old news

Offline TorQuePimp

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Re: offset valve seat flow numbers
« Reply #49 on: November 30, 2017, 08:05:32 PM »
Even CNC machined ports can vary, you would still have to flow test them first to make sure they are of the same flow, or the test goes out the window. Still I believe flow guides are a lousy way to test a head flow. Air can flow 360 degrees around the inlet guide, but with the T-Body and intake it must follow what is actually being used to supply the air. I believe that the port MUST BE ported differently with a manifold and T-body attached to get the best results. That's why we do it that way. I also believe there is more difference in porting with a manifold and the brand T-body actually used, than an offset seat alone can provide, you should actually do both. I also believe that the offset would be different from a guide to a manifold/ T-body. If you want to be the best, you need to do the most. Let the s**t storm continue....    JMHO  TIMINATOR

I have 2 programs that have been ran over 100 times for one and 70+ for the other that both clean up 100% and flow within 1% of another set to set every time.

Good bad indifferent they flow that close on the bench every time as the time was taken to make changes to vectoring and cutting speed,pre cutting the seat ID to make sure the tool doesnt deflect from taking too big a bite.

Not all heads or programs come out this good it takes cutting from a few to quite a few but it can be done

use the same valve for testing both heads on the flow bench would help as well

Then find a test engine or bike.....id prefer a engine only test OR someone with a climate controlled dyno cell

And see what there is to the offset seat profiles

Offline Matt C

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Re: offset valve seat flow numbers
« Reply #50 on: December 01, 2017, 07:30:46 AM »
Even CNC machined ports can vary, you would still have to flow test them first to make sure they are of the same flow, or the test goes out the window. Still I believe flow guides are a lousy way to test a head flow. Air can flow 360 degrees around the inlet guide, but with the T-Body and intake it must follow what is actually being used to supply the air. I believe that the port MUST BE ported differently with a manifold and T-body attached to get the best results. That's why we do it that way. I also believe there is more difference in porting with a manifold and the brand T-body actually used, than an offset seat alone can provide, you should actually do both. I also believe that the offset would be different from a guide to a manifold/ T-body. If you want to be the best, you need to do the most. Let the s**t storm continue....    JMHO  TIMINATOR

The intake port entrance has to be developed/shaped with the intake tract in mind and attached to the port.
(Wet & dry flow tests with that thing on there will tell you what you need to know)

Once you have that nailed down, you really don't NEED to attach it for subsequent tests. You already have the
data, with and without. (and I save everything)

Everyone has their own way of doing things. That's what makes the world go around.
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Offline HD Street Performance

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Re: offset valve seat flow numbers
« Reply #51 on: December 01, 2017, 07:39:14 AM »
Tim & John I agree with what you both are saying.
Will the added airflow make more horsepower though? In my opinion that will depend on if the pressure differential across the seat is close to even around the perimeter of the valve while adding this airflow potential. There are many airflow enhancers that will have guys hugging their flow bench but for various reasons don't work in the real world. Then we have nothing more than airflow challenges.

Offline Matt C

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Re: offset valve seat flow numbers
« Reply #52 on: December 01, 2017, 08:52:03 AM »
It's a quality vs. quantity thing. I'd trade lower CFM numbers to get more uniform
velocity through a port any day of the week.

I don't get hung up on CFM numbers. Velocity gradients are more detrimental
than anything else.

(Most "ported" heads out there flow more than enough in raw CFM terms)
« Last Edit: December 01, 2017, 12:01:57 PM by MCE Performance »
Life is like a roll of TP. The closer you get to the end the faster it goes.

Offline sbcharlie

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Re: offset valve seat flow numbers
« Reply #53 on: December 02, 2017, 04:45:24 AM »
i was busy this week hosting a porting class.  on this subject  i used a r-3 to digitize the stock valve seat profile, the refresh of the valve seat was to stock values. its interesting on porting a head with off set seats. thanks sbc

Offline sbcharlie

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Re: offset valve seat flow numbers
« Reply #54 on: December 20, 2017, 10:28:15 AM »
another video on offset valve seats https://youtu.be/tgGM7F-4GBE  thanks sbc

Offline sfmichael

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Re: offset valve seat flow numbers
« Reply #55 on: January 01, 2018, 11:51:17 PM »
interesting thread - thanks to all  :up:
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