This seems to be a buz word... What does it mean?
I'd figure rhinestones with too much exhaust cam to the rest of the build may be "over exhausting" but that that'd be about it..
Max
Too much exhaust duration or a high intake/exhaust flow ratio. You don't want to know what I think about that because it's the opposite of what everybody else does. :wink:
good question Max, I'm curious to the answer as well (maybe I even helped inspire the question?). My little pea brain kinda thinks that as longs as the fuel supply keeps up with the air flow, why would the torque suffer? ....although I would think that would be contingent on the exhaust creating enough back pressure. so, how much is enough back pressure?
Quote from: wfolarry on May 25, 2009, 02:53:09 PM
Too much exhaust duration or a high intake/exhaust flow ratio. You don't want to know what I think about that because it's the opposite of what everybody else does. :wink:
actually, I would like to know...I'm all ears:
(http://i381.photobucket.com/albums/oo256/wannabmayor/Smileys/aod_ears.gif)
:teeth:
The goal is to open and close the valves throughout the crank rotations and keep the torque and cylinder pressure maximized. Increased flow and/or increased cylinder volume gives increased power. In short, the intake/exhaust moved less volume as the rpm is increased.
Restrictive exhaust - close early - the cylinder volume is not completely emptied of exhaust gases, has residual pressure and the inlet charge is compromised by exhaust pressure and spent gases still in the cylinder.
Exhaust is effectively designed and timed correctly; it will not have residual pressure at the closing point. It is possible to help draw clean intake charge into the cylinder referred to as scavenging.
Over exhaust - close later - the cylinder volume will be contaminated with residual exhaust gases coming back toward the cylinder, lessen the total cylinder filling, in turn reduces the cylinder pressure due to the exhaust system seeing atmospheric pressure.
QuoteOver exhaust - close later - the cylinder volume will be contaminated with residual exhaust gases coming back toward the cylinder, lessen the total cylinder filling, in turn reduces the cylinder pressure due to the exhaust system seeing atmospheric pressure.
Good stuff now what's the best way to control this problem..
BTW Larry I'd bet that you are not alone.. Max
QuoteI'm all ears
Why?
I been listing to my computer and all I hear is the fans.. :teeth: Max
Quote from: MaxHeadflow on May 25, 2009, 05:37:09 PM
QuoteOver exhaust - close later - the cylinder volume will be contaminated with residual exhaust gases coming back toward the cylinder, lessen the total cylinder filling, in turn reduces the cylinder pressure due to the exhaust system seeing atmospheric pressure.
Good stuff now what's the best way to control this problem..
BTW Larry I'd bet that you are not alone.. Max
WildThings TW-26g cams
Variable Valve Timing
Quote from: MaxHeadflow on May 25, 2009, 05:40:57 PM
QuoteI'm all ears
Why?
I been listing to my computer and all I hear is the fans.. :teeth: Max
you mean your computer don't have the "word to talk" software? well, mine must be a newer version. :smilep:
Quoteyou mean your computer don't have the "word to talk" software? well, mine must be a newer version.
Oh,, I sorry mayor,,, Didn't know you couldn't read.. :teeth: Max
Quote from: MaxHeadflow on May 25, 2009, 05:37:09 PM
QuoteOver exhaust - close later - the cylinder volume will be contaminated with residual exhaust gases coming back toward the cylinder, lessen the total cylinder filling, in turn reduces the cylinder pressure due to the exhaust system seeing atmospheric pressure.
Good stuff now what's the best way to control this problem..
BTW Larry I'd bet that you are not alone.. Max
On a two stroke make sure your expansion chamber is matched to your port timing :soda:
Joel 2001 FLHT
Barny here Max , perhaps do a dyno run ,with what you have, then one with a washer in the exaust port head, drilled out to restrict the out let ,eg if you have1, 3/4 inche put it at1,1/2, this im sure will flow back to the port more so than one down further, like the old two stroke motors,see how the dyno excepts this towards your inlet over lap , be nice to try ,if it was variable it im sure it would flow different numbers,but as it was said before variable cam timming will be on the agenda for HD in the future easy to do ,cheers Barny
Quote from: MaxHeadflow on May 25, 2009, 10:44:30 PM
Oh,, I sorry mayor,,, Didn't know you couldn't read.. Max
that's ok, happens all the time. :teeth: that's why I prefer when people post pictures of how they did something. :wink: a picture
says a thousand words...
>What does it mean<
Drag pipes on a street bike.
You might find these next three interesting.
95" @ 9.7:1 CV40 V&H Straight Shots
[attachment removed after 60 days by system]
95" @ 9.7:1 CV44 Borzilla
[attachment removed after 60 days by system]
Borzilla CV44 vs. V&H CV40
[attachment removed after 60 days by system]
Quote from: wfolarry on May 25, 2009, 02:53:09 PM
Too much exhaust duration or a high intake/exhaust flow ratio. You don't want to know what I think about that because it's the opposite of what everybody else does. :wink:
Larry we do want to hear what you think. The following is a qoute I saw on Speed Talk
"If the results don't agree with the Theory,
believe the results, and get a new Theory"
Red,
I assume the better curve shows what a the 44 can do over the 40 with a set of good flowing heads.. What is interesting is that some like to say CV self compensate on the low end but it's obvious here that they don't...
Quote"If the results don't agree with the Theory,
believe the results, and get a new Theory"
I would change this a little.. "If the results consistently don't agree with the Theory" One of the biggest problems is that bad data leads to bad theories. Max
This logic may hold water if the builds were identical time after time. Unfortunately they are not.
Max, what I found interesting is it has been reported on a few occasions that a Borzilla is to much exhaust for a 95", TQ dips and all that.
What I find to be true is the better the heads breath on BOTH ends, the better the potential of the entire rpm range the cam is designed to work in, including the low end. A wise man once told me "if you choke your exhaust in an attempt to improve your low end, you should rethink you system".
I also have heard a lot about "over exhausting" and like you I am waiting for the explanation.
IMO exhausting an engine in and of it's self is a system. Not just an arbitrary thing, defined by the size of a valve.
I might believe that if a cam such as a TW37 with these heads could reach 107+ tq rather consistently with 9.2/1 corrected compression in an older model at 95". I don't see that happening with many heads. I have a set of competitor heads here now that if I was looking for problems would not be able to find them they are high flow from the bottom up and exhaust is right there at 80+ % all the way up. Problem is this only makes a little over 90hp and 95tq with a good pipe (roadrage) and tune (Latus), TW6h cams.
Red your heads are just working well with the cams you chose and of course the pipe just enhances that. I think that heads that don't have flow problems such as vortexing and hot spots work better across the board but still not sold on 90+ exhaust ratio with most cams, or for that matter 70% range with some cams. Matched parts work well together, simple as that. VE is picked up when the exhaust is working properly during overlap and assuming the cam choice is not too long that is where the desired torque band occurs. I am inclined to like the idea of a little more head flow and throttle that back with a shorter cam rather than a longer cam and an inadequate head
>assuming the cam choice is not too long<
Long cams = higher rpm range, and as you know RPMs have a big effect on exhausting.
QuoteI think that heads that don't have flow problems such as vortexing and hot spots work better across the board but still not sold on 90+ exhaust ratio with most cams,
If you were designing a set of heads from scratch, it would be advantageous to pick a more appropriate intake to exhaust valve ratio. Since head porters here are dealing with heads that HD has already designed, shrinking the exhaust valve to get more intake might be more than what the average guy wants to pay.. (I guarantee mayor ain't buyin' it.. :wink:) Might as well buy a new head. With that in mind it seems to me that you get the best flow out of what you got and find a set of cams intake and exhaust that giver you a power band you want. I think on of the issues here is that many find a set of heads with good power numbers, a cam on another build that gave good numbers, and an exhaust system that give nice torque where wanted (and sound). They throw the combo together and it don't run.. The problem is that they don't look at the motor as a complete system that needs to function with all the components together.. They complain that the head, cam, or exhaust is a piece of poop..
Now me? I don't mind trying different combos and striking out (well I do but I expect to strike out occasionally :teeth:) .. Eventually you get a hit or two but there is still that swing and miss.. Those wanting to get on base need to go with proven combos.. Even then it doesn't guarantee that here is some obscure problem that needs sorting out..
Max.
Quote from: MaxHeadflow on May 26, 2009, 08:32:13 AM
If you were designing a set of heads from scratch, it would be advantageous to pick a more appropriate intake to exhaust valve ratio. Since head porters here are dealing with heads that HD has already designed, shrinking the exhaust valve to get more intake might be more than what the average guy wants to pay.. (I guarantee mayor ain't buyin' it.. :wink:)
Max.
well, I wouldn't be the least bit surprised if my level of cheapness may be far more advanced than the average person. (http://i381.photobucket.com/albums/oo256/wannabmayor/Smileys/Smileyremovingshades.gif) although, I do agree that most enthusiasts have a price point that they are unwilling to cross in pursuit of being faster than their buddies. Lucky for me, I'm satisfied with just being cooler (http://i381.photobucket.com/albums/oo256/wannabmayor/Smileys/pimp.gif)
:teeth:
Quote from: mscoolone on May 25, 2009, 05:25:32 PM
The goal is to open and close the valves throughout the crank rotations and keep the torque and cylinder pressure maximized. Increased flow and/or increased cylinder volume gives increased power. In short, the intake/exhaust moved less volume as the rpm is increased.
Restrictive exhaust - close early - the cylinder volume is not completely emptied of exhaust gases, has residual pressure and the inlet charge is compromised by exhaust pressure and spent gases still in the cylinder.
Exhaust is effectively designed and timed correctly; it will not have residual pressure at the closing point. It is possible to help draw clean intake charge into the cylinder referred to as scavenging.
Over exhaust - close later - the cylinder volume will be contaminated with residual exhaust gases coming back toward the cylinder, lessen the total cylinder filling, in turn reduces the cylinder pressure due to the exhaust system seeing atmospheric pressure.
If this were the case the bigger the exhaust the better the engine will perform.............but it`s not the case.
>What is interesting is that some like to say CV self compensate on the low end but it's obvious here that they don't...<
AFR data might show why......
Take the 110 exhaust port for example. Huge, 1.625 exhaust valve and 88% throat. 220cfm on a good day out of the box with very slow velocity.
Quote from: hardyheadscom on May 26, 2009, 08:56:42 AM
Quote from: mscoolone on May 25, 2009, 05:25:32 PM
The goal is to open and close the valves throughout the crank rotations and keep the torque and cylinder pressure maximized. Increased flow and/or increased cylinder volume gives increased power. In short, the intake/exhaust moved less volume as the rpm is increased.
Restrictive exhaust - close early - the cylinder volume is not completely emptied of exhaust gases, has residual pressure and the inlet charge is compromised by exhaust pressure and spent gases still in the cylinder.
Exhaust is effectively designed and timed correctly; it will not have residual pressure at the closing point. It is possible to help draw clean intake charge into the cylinder referred to as scavenging.
Over exhaust - close later - the cylinder volume will be contaminated with residual exhaust gases coming back toward the cylinder, lessen the total cylinder filling, in turn reduces the cylinder pressure due to the exhaust system seeing atmospheric pressure.
If this were the case the bigger the exhaust the better the engine will perform.............but it`s not the case.
During overlap, there is charge exchange possible between the inlet and exhaust ports. If the intake and exhaust timing events have been optimized to produce maximum cylinder filling and pressure, the TDC overlap activity has to be a balance of intake opening and exhaust outflow. The inlet port effectiveness and valve timing events control cylinder-filling capability.
What controls exhaust effectiveness at a given RPM range with a fixed size inlet port & valve? Lag, Inertia? A balance of exhaust valve timing events, the emptying of the cylinder volume and exhaust outflow?
All true which is why one size that flows well does not fit all.
People use different cams, pipes, compression. Many heads work OK but to leverage the advantages of the overlap cylinder filling and emptying the relationship and exhaust flow and velocity come into play during this period. Remember Mayor this topic comes up again.
Quote from: Deweysheads on May 26, 2009, 11:03:58 AM
All true which is why one size that flows well does not fit all.
People use different cams, pipes, compression. Many heads work OK but to leverage the advantages of the overlap cylinder filling and emptying the relationship and exhaust flow and velocity come into play during this period. Remember Mayor this topic comes up again.
yep, I think this is definitely a good topic for discusion. I think there may actually be enough grounds for two sepperate conversations.....one based on exhaust port flow in the heads, the other being the actual exhaust system.....I guess that's the tough part for you pro's to make sure both work together.
to kinda hi-jack Bruce's over exhaust question, I'd like some comments on the results of the autotune (T-Max) results that I got using my tunable Supertrapp internal disc mufflers (currently 18 discs in each). I used the base map for Rinstone TD's and stock 88" ('01-'04). Here's the front:
(http://i381.photobucket.com/albums/oo256/wannabmayor/HTT%20hosted%20pictures/3328rpmautotunefrontfueloffset.jpg)
and the rear offset:
(http://i381.photobucket.com/albums/oo256/wannabmayor/HTT%20hosted%20pictures/3328rpmautotunerearfueloffset.jpg)
the blue was baseline, and the green was what the autotune changed from the base map settings. if I'm reading this correct, the front cylinder needed fuel to be trimmed out and the back cylinder needed fuel to be added? if that's the case, couldn't I add discs to the front muffler and subtract discs from the back cyclinder to tune the mufflers more to the bike?
:pop:
the other being the actual exhaust system
Well many assume their system actually scavenges, some do, so do not very evenly, so do overly well.
QuoteIf this were the case the bigger the exhaust the better the engine will perform.............but it`s not the case.
I would say not always the case..
I had a 95 ci TC FXDX 10.8 to 1 CR, a 122 cfm intake and 115 CFM exhaust home ported heads(didn't knoe how bad the intakes were until I got the flow bench and at that time the motor no longer existed), G carb, CS slipons, TW50 cam.. Bike ran great, tried a TH and power dropped.. If I'd known about baffle bending I would have tried it. When to arIIIs and the motor picked up 6 hp..
Flip side,
113 SnS evo 11 to 1, 640 cam mild clen up on the stock heads pick up 10 hp (114 to 124) going from pretty much any high perforamce muffler to a 2 1/4 stepped exhaust system with straight through glass pack exhaust. All it wanted was flow...
Max
Mayor,
I would have used the VnH true duals as the pipe diameter is probably closer to you pipes.
Sonny,
Caught me on that one.. :wink:
Max
the only V&H I saw a map for was staggered duals for Softails...
map 428 was the base map I used.
Mayor.... maybe you are under exhausting :wink:
Quote from: Sonny S. on May 26, 2009, 02:00:39 PM
Mayor.... maybe you are under exhausting :wink:
that's what I was thinking with the front pipe, yet seems like the rear pipe probably flows a little more than needed (but probably ok). I may look for 4 3" discs to through on the front pipe muffler.
How bout valve timing events?
Was the lift and the duration checked at the valve to insure the cam is installed per specific requirements, Do both cylinders have equal amounts of cylinder compression?
Could there be a manufactures error in one of the cams/hydraulic lifters?
Could one cam be lagging behind due to lash adjustment, sprocket wear, chain stretch?
Could retarding or advancing the camshafts improve on the desired performance?
Over exhausting? There is no 'one size fits all' answer, although exhaust manufacturers may want you to believe that. One thing that must be kept in mind, and most people overlook, is the state of the air/fuel mixture. On one side of the equation you basically have atmospheric pressure, on the other you have a heated compressed gas. An exhaust system must not only pass this compressed gas, but it must also control the expansion rate. The expansion rate, I feel, plays a more important role in velocity, than simply the size and shape of the exhaust, to put it simply.
With this being the case, over exhausting would then be defined as uncontrolled expansion of a gas.
Quote from: mayor on May 26, 2009, 01:31:08 PM
the only V&H I saw a map for was staggered duals for Softails...
map 428 was the base map I used.
I'll look at home but I bet you are right and I'm in error..
BTW based on what the thing leaned out on the front The swing on the rear makes sense since it is referenced to the front.
QuoteThere is no 'one size fits all' answer, although exhaust manufacturers may want you to believe that.
absolutely,,,
Max
In fact the only exhaust rule of thumb I know of is:
A well designed exhaust system will work better than a poorly designed one no matter what the application.
IE: Thunderheader, Fatcat, Supermeg, etc work well for most all builds, whereas straightpipes, bagger tru-duals with open muffs, and other systems produced for looks rather than performance, do not work well no matter what they are bolted onto.
Just my $.02,
Bob
The V&H true duals & Hooker adjustable slip ons played fairly well on my bagger with the HQ split duration cams, but not so much with the Tman cams I'm running now...just food for thought Bob not trying to start an argument :teeth:
Quote from: 05FLHTC on May 26, 2009, 05:02:50 PM
The V&H true duals & Hooker adjustable slip ons played fairly well on my bagger with the HQ split duration cams, but not so much with the Tman cams I'm running now...
Can you elaborate? You must admit your comment isn't very technical addressing the differences in cams and how they worked with the V&H w/Hooker slipons. :teeth:
Did you dyno tune the different cams with the same exhaust? What was the finding?
Yep the Propipe busted the rear nipple off for the 2nd time & I had the duals & Hookers from prior. Took it in had it dynoed, the setup duals actually made more on the bottom end & left about 6 HP off the top from what I recall. This was on the same 250I at Valley racing & with the same dyno operator Brian. When I decided to swap out the 33G's for the Tman 625's over the winter, they did not fair well with the duals but did well with the Propipe.
By the way at that time the pipe then & continues to shine now was the new Bub 7 (2 in 1), the only way we could get anything to compare close was to close off a couple of rows on the Propipe stock baffle. That Bub has performed well on everything that it has been tried on...I'm just tired of forking out 500 bucs for another exhaust system & my Propipe sounds good & only lack like maybe a couple numbers behind.
Hope that was technical enough :wink:
Edit addition so I guess if I had to draw a conclusion based on my own experience, the split duration cams do not seem to be as sensitive to exhaust needs scavenging ... or maybe it was just a fluke coincidence?
Quote from: 05FLHTC on May 26, 2009, 05:52:34 PM
When I decided to swap out the 33G's for the Tman 625's over the winter, they did not fair well with the duals but did well with the Propipe.
Guess what I'm asking is for a more specific comparison such as where the power moved from and/or to with the change. Did the power increase in an area where the other pipe lost? etc.
Where did the duals look desireable over the 2into1, if at all?
IMO cam timing can make even the best of pipes look bad.
QuoteEdit addition so I guess if I had to draw a conclusion based on my own experience, the split duration cams do not seem to be as sensitive to exhaust needs scavenging ...
Totally agree with this statement. :wink:
Bob
Quote from: FLTRI on May 26, 2009, 06:22:37 PM
Guess what I'm asking is for a more specific comparison such as where the power moved from and/or to with the change. Did the power increase in an area where the other pipe lost? etc.
Where did the duals look desireable over the 2into1, if at all?
IMO cam timing can make even the best of pipes look bad.
Yep moved the Tq & Hp like said about 6 numbers from 6K rpm & transferred it right into the 3K rpm range. I was shocked based on all the readings & bad rap the duals receive, never would have believed it & would not be saying it without seeing it on the dyno. Oh and buy the way, nothing & I mean nothing sounded as good as them true duals & hookers did though they were a tad loud at 80 mph on the slap IMHO.
Edit sorry Max didn't mean to side track the thread
Quotefrom 6K rpm & transferred it right into the 3K rpm
So the Duals made 6 less hp/tq @6k but made 6 more hp/tq in the 3k range as compared to a Propipe?
Sorry just trying to garner some knowledge from the comparison as I have not done back to back tests with these 2 exhaust systems, but definitely interested.
Thanks,
Bob
O.K...............it seems some have a good grasp to what`s going on... so when is a good time for the intake to close and the ex to open.
Quote from: hardyheadscom on May 26, 2009, 09:36:38 PM
O.K...............it seems some have a good grasp to what`s going on... so when is a good time for the intake to close and the ex to open.
When I finished eating and gotta take a .... :wink:
QuoteEdit sorry Max didn't mean to side track the thread
Actually you are right on the money.. See below
QuoteBy the way at that time the pipe then & continues to shine now was the new Bub 7 (2 in 1), the only way we could get anything to compare close was to close off a couple of rows on the Propipe stock baffle.
So wouldn't you say that the pro-pipe was over exhausting? By blocking it off you picked up power.
IMO Hookers make good low end TQ because they are not a "flow through" exhaust and have a good reflection point.. Cycle shacks are another.. Give a nice power band but not maximum power..
QuoteEdit addition so I guess if I had to draw a conclusion based on my own experience, the split duration cams do not seem to be as sensitive to exhaust needs scavenging ...
If you mean longer exhaust duration than intake, I would disagree here. I assume the split duration cam did better than the non split one with the propipe when the holes were covered. over exhausting..
BTW
Larry not sure the answer to your question but I'd bet the exhaust system will have an effect as to where the best timing is and vise versa..
Bob, I though you didn't think that an exhaust would have any effect on pushing the TQ curve around..
Max
Quote from: MaxHeadflow on May 26, 2009, 10:07:35 PM
Bob, I though you didn't think that an exhaust would have any effect on pushing the TQ curve around..
Max
What I meant to convey was the cam's profile sets the peronality and the exhaust can either help or hurt that personality show through.
Peak power rpm should be dictated by the cam profile not the exhaust.
QuoteWhat I meant to convey was the cam's profile sets the peronality and the exhaust can either help or hurt that personality show through.
Peak power rpm should be dictated by the cam profile not the exhaust.
Gotcha,
We're saying the same thing only, I like to add that you can used the exhaust to change the personality.. I like to think of all the major systems/components of a motor as a simple tuned circuits :smileo:.. In electronics the simplest is an LCR (LC is the ideal but there is always R).
http://www.electronics.dit.ie/staff/ptobin/lab007.pdf
Now if you take all these circuits and stack them together right you cam make very good power.. Miss-tune a bunch and you get them fighting each other and a sucko output.
The dreaded torque dip is a prime example.. But you can also use the "miss tuning" of the exhaust to spread a torque peak of narrow LSA cam.. 2 into 1s? They have 2 tuned circuits, one in the head pipe, the other in the muffler.
Max
FLTRI well put.
The exhaust is the second most important consideration after cam profile selection. Unfortunately, more often than not, it is one of the last things people consider, almost as an after thought.
Bolting on some 2.5 inch head pipes on a stock motor will most certainly 'change the personality'
Backpressure as some refer to, is expansion rate.
Here another data point..
TC 116
625 cams
Gcarb or CV51 with about 4/6 different manifolds
10.8 to 1 CR
head were some prototypes with 2 in intakes, 1.615 exhausts
5 different exhausts
Best the motor always made about 124hp /124-8 tq sae (in 4th) with including 3 hours on the dyno with one setup. The exhaust did not make any difference in HP output.
After I swapped out the heads I put these on the flow bench... Exhausts flowed about 115cfm 0.6 lift at 10 in H20..
Motor actually made the best HP / TQ with a 260/ 266 cam I had in there for a short time..
Max
Quote from: MaxHeadflow on May 28, 2009, 07:17:42 AM
The exhaust did not make any difference in HP output.
Quote from: FLTRI on May 27, 2009, 08:09:09 AM
Peak power rpm should be dictated by the cam profile not the exhaust.
We do agree. :teeth:
Disclaimer: My statement only includes free-flowing exhausts.....corks will always kill power.
Quote from: FLTRI on May 28, 2009, 07:57:46 AM
Quote from: MaxHeadflow on May 28, 2009, 07:17:42 AM
The exhaust did not make any difference in HP output.
Quote from: FLTRI on May 27, 2009, 08:09:09 AM
Peak power rpm should be dictated by the cam profile not the exhaust.
We do agree. :teeth:
Disclaimer: My statement only includes free-flowing exhausts.....corks will always kill power.
Just to clarify here. In the case the exhaust "system" didn't make any difference because the port was causing the restriction.. The "whole" system was limited by the port. The only way to increase flow was to increase exhaust duration..Changing stuff on the down side of the port made no difference. In this case more time the value was open the better.
My point was "Why limit yourself with a poor flowing exhaust port?" Use the pipe to get the band you want..
You must only deal with exhaust ports that don't flow.. :wink:
QuoteMy statement only includes free-flowing exhausts.....corks will always kill power.
How do you explain the 113 that I that only make more HP when all restrictions were removed form the exhaust?
Max
QuoteMy statement only includes free-flowing exhausts.....corks will always kill power.
QuoteHow do you explain the 113 that I that only make more HP when all restrictions were removed form the exhaust?
No argument here, so no explanation necessary.
Max,
If the port size/design is crap then it makes no difference how big the exhaust is. The only point I'm trying to make here is that the exhaust is something that hurts or helps a design, not dictate peak numbers, unless of course it is a restrictive system. I've seen the same
peak numbers with "Zoomie" straight pipes as with a Boarzilla and LSR, but the Zoomies are not street/rideability friendly and kill low end power.
Bob
I'm trying to find something to argue about with you but I guess I can't... :teeth: Max
I got a few questions guys. :teeth:
Bruce
So if you had a set of heads that had less than stellar exhaust ports you may be able to use a longer exhaust duration cam to make up a little flow and increase hp numbers a bit.? As long as you don't sacrifice too much compression.
And if you had a set with good intake and exhaust ports and bolted on some restrictive style pipes the TQ should come up a bit and then HP will suffer. And vice verser. ? It wants what it wants to be happy. And you guys with the dyno got the advantage here as a test and tune aid to find the best pipe to complement the build . But it seems you may have to spend a lot of scratch on differant pipes and set ups to find the magic exhaust system for your build.
Is there a short cut for the average Joe ?
Proven package maybe a short cut.
If the TQ improves with the restrictive pipes where did it come from , And How? Reversion ? ,Increased exhaust velocity? scavenging ?
Exhaust gas expansion ?
Doesn't the exhaust gas expansion and exhaust velocity go hand in hand , and is this what induces scavenging?
What would help induce scavenging a restrictive exhaust OR a free flowing exhaust? Or is it in the port design ? OR both ?
So Bob, Have you ever seen an improvement on the dyno with a bike with free flowing exhaust pipes and the lollipops installed make a difference as far as fine tuning the exhaust? Or is it a waste of time?
Just trying to learn a few things here, this is very interesting to me. Wanted to keep the tread going.
I don't have access to a lot of equipment to test things so I envy you guys a bit . LOL :wink:
Quote from: ICANTD55 on May 28, 2009, 01:18:53 PM
So Bob, Have you ever seen an improvement on the dyno with a bike with free flowing exhaust pipes and the lollipops installed make a difference as far as fine tuning the exhaust? Or is it a waste of time?
Lollipops are bandaids that help to make the exhaust work better @ mid/lower rpms. They can loosely be called tuning devices.
In other words, if the exhaust system is not a good design there are things/tricks that can help them work better.
IMO, it is best to start with a good design and adjust as needed from there. Straight pipes are the worst for street applications and stock mufflers are worst for racetrack applications. Find the happy medium (2into1 :idea:) and it will perform great in both applications.
HTH,
Bob
Baa, it's all wave tuning. Wave tuning, wave tuning, wave tuning. :rtfb:
Pipes too open? The waves think your pipe is a lot shorter than it really is.
Glasspacks? The waves see your glasspacks as a megaphone with a suddenly contracted exit.
Lollipops? An alteration of the wave tuning.
Throw pipes at your bike with no response? Your engine's configuration cannot utilize wave tuning for its benefit.
Drag pipes on a Shovelhead? No problem, that engine can't take advantage of wave tuning either.
Ok Bob, I will take that as a no. with a twist, :wink:+
Aren't some good 2-1 exhaust tuneable? Like your two favorites the super trap and the thunder header{ bending tabs}
And haven't some guys on this websight adapted the traps to the Boarzilla and fat cat with success?
Not being a smart a$$ just saying if its a good exhaust cant it be made better? or better suited to your build.
And I would consider all of the above pipes good pipes.
I would not consider drag pipes at all, but some guys love um.
I know you have tuned a lot of bikes Bob that's why I asked you. I just don't believe the perfect pipe comes as is out of a box. And this is what I would like to learn more about.
So,
Hey Fuzz, got a recommendation for that :rtfb:
I still like the look of cycle shacks on the shovels. :wink:
>>Baa, it's all wave tuning. Wave tuning, wave tuning, wave tuning<<
Well, "Potty mouth" fire! 'Bout time someone finally said the "magic" words! On the exhaust side, valve timing, exhaust duration, pipe diameter and length, and to a slightly lesser degree port design and flow all have a role to play in both clearing the cylinder and to aid the fill cycle during the overlap period. Get them all "right" and you gain power over a specific RPM range. Get them wrong and you will lose power from inadequate fill (reduced VE), less trapped mass, short circuit losses, residual exhaust gasses (charge dilution), and so on.
Just as dry flow numbers on the intake side can skew how a head will actually perform under operating conditions, dry exhaust flow numbers and intake to exhaust ratios can be misleading as well. Remember, the object on the exhaust side is to not only clear the cylinder of burned gasses, it must also create the negative pressure waves to lower the cylinder below atmospheric pressure at the proper time to aid cylinder fill and thus enhance VE. Depending on the application and power band, this can be done with the proper exhaust system, cam, head, and with intake to exhaust ratios ranging from 65% to 90% for NA motors, higher ratios for turbo and blower motors. CharlesTaylor and others proved that a motor would not lose appreciable power with intake to exhaust ratios of 75% way back in the 1940's. Since then, it's been found that ratios less than that can actually improve power in certain engnes and applications.
Flow is good, but as I've said before, it's not the whole story. BTW, pipe diameter sets the exhaust velocity, pipe length sets the tune point. Holds true for primaries (headers), collectors, and megaphones or muffler cans. And then there is volume ... the gasses need the right volume to expand and develop those all important pressure waves. The best port in the world is all but useless if it's matched with the wrong cam or exhaust system for the application at hand.
Back pressure? No thanks. I want my exhaust system to be as low restriction as possible but with the right balance of tuning and noise abatement. If you think back pressure is good, just stick a large potatoe up yer pipe and see what happens :>)
EDIT: Over exhausting to me means an exhaust system (includes head and cam) that is tuned to the wrong portion of the RPM band. Too large or too small of a primary pipe and/or the wrong length(s) and the power curve(s) will definitely show the effects. Motorcycle exhaust systems are far more challenging to design as you have both space limitations and "looks" to contend with. By the same token, if the head, cam, and intake are wrong for the pipe/power band desired then it's gonna be tough to optimize an exhaust system tp produce best power in an RPM range that the cam/head/intake are not suited for. The engine is a system and all of it's parts must work together if one wants more than average power from it.
"The Devil is in the details."
Ed! You're making me seasick, and I'm on land! :teeth:
Reminds me of when I used to play guitar, I thought I was good, and then I would see someone that just blew me away. Made me want to burn the guitar and rewire the amp into a ham radio. :smilep:
But I am reminded why I "cheated" and used Pipemax and Engine analyzer pro to make my exhaust.
55, if you feel like spending 100 bucks, "Design and Simulation of 4 stroke engines" is a really good book. A lot of it is over my head, or more than I want to know, but it covers exhaust theory well.
This is a good read:
http://www.superchevy.com/enginemasters/articles/hardcore/0505em_exh/index.html
Fuzz,
Good link ... the man know his chit! The 45 deg. V-Twin does it's best to negate a lot of what works with other designs, but thankfully, most of it holds true. The book you referenced is also good. IMO, it ranks right up there with C.W Taylor, Sir Harry, A. Bell, and the Denish books as "must reads" for those who are serious about wanting to do something other than bolt stuff together and pray to the "motor gods" for success ... and wave a dead chicken :>)
Dead chicken, gotta try that someday! Will frozen cutlets work? :teeth:
QuoteWell, "Potty mouth" fire!
And save matches?
QuoteEDIT: Over exhausting to me means an exhaust system (includes head and cam) that is tuned to the wrong portion of the RPM band. Too large or too small of a primary pipe and/or the wrong length(s) and the power curve(s) will definitely show the effects.
This is definitely right on..
QuoteCharlesTaylor and others proved that a motor would not lose appreciable power with intake to exhaust ratios of 75% way back in the 1940's.
Given the ability to select intake to exhaust ratios with valve sized properly this is the way to go but he also mentions that larger exhaust sizes and help with pumping losses. Since for the most part here I'm talking about stock TC heads where changing intake to exhaust ratios can increase the cost significantly (ie, staying with the valve seats) , I'll ask "What's wrong with makin' the exhaust valve bigger?"
BTW I need to think about Z factor some..
QuoteSince then, it's been found that ratios less than that can actually improve power in certain engines and applications.
I think in this case you'll find the motor way over square.. Something most all HDs aren't.
55
QuoteSo if you had a set of heads that had less than stellar exhaust ports you may be able to use a longer exhaust duration cam to make up a little flow and increase hp numbers a bit.? As long as you don't sacrifice too much compression.
Intake close was about the same between the 2 cams the longer cam actually closed at 54, shorter at 55 so CCP wasn't sacrificed.
QuoteIs there a short cut for the average Joe ?
Proven package maybe a short cut.
It's called trail and error, thou your answer is good.
QuoteIf the TQ improves with the restrictive pipes where did it come from , And How? Reversion ? ,Increased exhaust velocity? scavenging ?
Exhaust gas expansion ?
Doesn't the exhaust gas expansion and exhaust velocity go hand in hand , and is this what induces scavenging?
Yes, no all of the above and none of the above... :wink:
QuoteWhat would help induce scavenging a restrictive exhaust OR a free flowing exhaust? Or is it in the port design ? OR both ?
As Fuzz hints and Ed preaches.. It's complex and not simple.. I remember Ed saying he's gone through a pipe or too. Weld something up, hack on it.. it don't work, send it to recycle and try again.. I've trashed more than a few pipes.. Nice thing is that high temp black paint is cheap and I like the color... :teeth:
Fuzz, Hows that ham radio werkin'?
Bruce
>Back pressure? No thanks. I want my exhaust system to be as low restriction as possible but with the right balance of tuning and noise abatement. If you think back pressure is good, just stick a large potatoe up yer pipe and see what happens :>)<................. :hyst: :hyst: :hyst:.........what your suggesting is over potatoeing
QuoteFuzz, Hows that ham radio werkin'?
I dunno, the 25-40KHz band isn't very popular. The only response I got was from my dog. :smiled:
I'll ask "What's wrong with makin' the exhaust valve bigger?"
How do you know you need a bigger one? What size is optimum? Does a bigger exhaust valve need less work to the port so that it doesn't 'overexhaust' it? If we are wave tuning which wave are we tuning to? Does a change in pipe size affect this? How does a collector affect this? Does a Thunderheader deal with the wave tuning better than other pipes? Has anybody looked inside their fatcat pipe before they put it on? If I add more discs to my supermeg am I overexhausting or tuning to an RPM that my motor will never see? Do equal length pipes help? Can drag pipes be made to work on the street? [I know everybody has run them at least once & liked the sound] Does longer duration on the exhaust side of the cam help? if so how? Do S&S cams with their early opening exhaust give up a lot of power? Does more lift help with less duration or does it hurt with long duration? If I have the long exhaust duration cams why can't I use my stock mufflers? Do stepped pipes work? Should I wrap my exhaust pipes to keep the heat in & make my bike faster? Should I blame my head porter when my bike doesn't make enough power because he didn't get the exhaust flow ratio right? [I know you want to :wink:] Just thinking out loud before I start working. Bye
Quote from: fuzznut5197 on May 29, 2009, 04:09:28 AM
QuoteFuzz, Hows that ham radio werkin'?
I dunno, the 25-40KHz band isn't very popular. The only response I got was from my dog.
Those frequencies are good acoustic frequencies for underwater telephones.. :wink:
Larrry,
Yes, no all of the above and none of the above... and maybe... I think we go back to pickin' what works. I think that unless someone wants to experiment, they should go with the recommendations of the person that is providing the heads. Proven combos.. One of the thing that gets me is people that say say things like "I want to do a Hippo build but I want to use different heads..." Well is ain't a Hippo build.. I would say what do you like about the Hippo build depending on the answer, look for an expert that provides the desired features and go with his recommendations. Want to use 570 cams, finds some that knows of builds that work with 570 cam.. Woods.. Every Piece is important.. Also make sure you know what you want...
QuoteDo stepped pipes work?
Yes if you understand how they work. :teeth:
QuoteIf I have the long exhaust duration cams why can't I use my stock mufflers?
Cuz you want you exhaust flowing out your exhaust and not your intake... :wink:
Max
>>Every Piece is important.. Also make sure you know what you want...<<
Every Piece is important.. Also make sure you know what you want...
Every Piece is important.. Also make sure you know what you want...
Every Piece is important.. Also make sure you know what you want...
Every Piece is important.. Also make sure you know what you want...
It's worth repeating :>) I'll add, it's important to be realistic with your goals as well. A Ferrari motor in a garbage truck may be "trick" to some, but most will find that it's an expensive mistake.
Unless you have the knowledge, patience, equipment, time, and money to embark on a engine development program sticking with proven combos makes a lot of sense for most ... but don't scrimp or cut corners. Especially when it comes to the final tune. Find a good tuner and get the most that the combo is capable of.
Change the recipe? That "angel food cake" might turn out to be a "butt brownie"!
Interesting exhaust stuff to read:
http://www.burnsstainless.com/TechArticles/techarticles.html
Quote from: wfolarry on May 29, 2009, 04:37:24 AM
I'll ask "What's wrong with makin' the exhaust valve bigger?"
How do you know you need a bigger one? What size is optimum? Does a bigger exhaust valve need less work to the port so that it doesn't 'overexhaust' it? If we are wave tuning which wave are we tuning to? Does a change in pipe size affect this? How does a collector affect this? Does a Thunderheader deal with the wave tuning better than other pipes? Has anybody looked inside their fatcat pipe before they put it on? If I add more discs to my supermeg am I overexhausting or tuning to an RPM that my motor will never see? Do equal length pipes help? Can drag pipes be made to work on the street? [I know everybody has run them at least once & liked the sound] Does longer duration on the exhaust side of the cam help? if so how? Do S&S cams with their early opening exhaust give up a lot of power? Does more lift help with less duration or does it hurt with long duration? If I have the long exhaust duration cams why can't I use my stock mufflers? Do stepped pipes work? Should I wrap my exhaust pipes to keep the heat in & make my bike faster? Should I blame my head porter when my bike doesn't make enough power because he didn't get the exhaust flow ratio right? [I know you want to :wink:] Just thinking out loud before I start working. Bye
Jess , Larry for a guy that nows his chit ,you sure ask a lot of questions .LOL :wink:
Just kidding Larry
Thanks Fuzz ,a good read:
http://www.superchevy.com/enginemasters/articles/hardcore/0505em_exh/index.html
55, if you feel like spending 100 bucks, "Design and Simulation of 4 stroke engines" is a really good book. A lot of it is over my head, or more than I want to know, but it covers exhaust theory well.
I will check it out muchos gracias ;D
I think a generic answer to Larry would be who the heck knows. Snippets of information out of context of the whole build are not the "exhaust system design" just components of them. We are handed what cards we are dealt and have to make them work. Twin cams come in a lot of variants now from 110" down to 88" and have various inherent baggage going in. What may be a good cam for one is crap for another and exhaust requirements change.
Guys build these motors with a lot of pre-existing hardware and try to get the square peg to fit the round hole and if they whittle and pound enough they fit but not well. Everyone looks for a plug and play solution and best you can hope for is a higher probability of success with a matched and tested combination. Then the tune and assembly details factor in, very important!
>>I think a generic answer to Larry would be who the heck knows<<
Likely true for most. There are tools and ways to predict engine behavior with a fair degree of certainty and accuracy ... but like everything else it's not a slam dunk and it takes time, effort, and dedication to get the data points and the tools "tweaked". I know a lot of folks poo poo the validity of engine simulators, but they can be a valuable asset. When used in conjuction with accurate flow data and so forth the results can be quite good. However, WYSINNWYG and GIGO definitely apply here :>) The casual user/owner/builder will always be faced with the dilemma(s) of too little cash, too many choices/opinions, limited resources, and a lack of reliable and factual data. The only thing I can offer for those folks is:
1. Educate yourself as much as possible ... and I don't mean just what you can learn on the net. While you are saving for that stroker or big bore kit set a little aside for :rtfb: and learn as much as you can before you buy the wrong stuff and try to make a silk purse out of a sow's ear.
2. Ask your vendors real questions that matter as far as what you are trying to accomplish. Avoid those that won't take the time to discuss your needs or make claims that just seem to be too good to be true ... they likely are! With your new found knowledge and some detective work it shouldn't be hard to flush the BS mongers out.
3. Realize that even with the "best" components there will be some variances from the "ideal". If you aren't getting what you expected there is likely a good reason for it ... time to use that new knowledge again and find the reason(s).
There aren't any shortcuts to building a good hi-po motor ... I've looked for 'em, believe me! If you do find 'em ... be sure to share :>)
QuoteI've looked for 'em, believe me! If you do find 'em
NOS? :teeth: Max
>>NOS? <<
Ummm ... NO! The "destroyer bottles" have no attraction for me. Turbo/Blower motors are fun, the "bottle" blows :>) If you are moving away from pump/race gas then go alky or nitro ... leave the laughing gas at the dentist, where it belongs! I like my shots to be "Jack" or Bacardi 151 :>) (and I don't give 'em to my motor ... damn pistons try to swap holes).
:potstir:
With the internet all kinds of information becomes available to any body that wants it [& knows how to find it]. It's what we do with that information that makes it or breaks it for some. Overexhausting, underexhausting or anything in between are terms that get thrown around enough that somebody will start to wonder if their build is optimum. Did I leave anything on the table? Could I have gotten more out of it? Maybe. Spend the money to find out. Don't want to spend it but want a definitive answer? Buy the bike from the guy that's got what you want.[It does happen] As far as exhausts go I can remember back in my Shovelhead days that Cycle Shack mufflers were the best bang for the $$. I think they still are. Not saying they are the best [I don't think any 1 system is best] but you can't go wrong for the money. My favorite pipe is the Thunderheader. Maybe it doesn't make the most power [or maybe it does] but I like the way it sounds. It's in the shed as I have a Propipe on now. I try just about everything once.
As for the valve size question I put a 1.610 in a 124 & made 170hp. [race bike] Another 124 I built with bigger valves [both intake & exhaust] made 170hp too but it will walk away from the other bike on the top end. The throat on the exhaust on the 1st bike is 1.390. A stock TC is 1.375. So did a .015" increase in throat size make all that power or was there some magic involved? :wink: There are a lot of good exhaust systems to choose from now so I would pick a good one, GET A GOOD TUNE, & ride it! The 2hp you lost by not picking the best will never be missed. Time for dinner.
One more thing. On the race bike we have a new pipe custom made by Brian Truesdale. He worked for White Bros. when the E pipe was the hot pipe. He moved back here from the left coast & is making custom pipes. I'll let you know how that works out when I have some facts to report back.
Some folks are happy with 1 HP/TQ per cube and others want more. You don't get that level of performance (generally) by just bolting stuff together ... if you do, you should be playing the lottery :>)
I've designed and built many intake and exhaust systems for all sorts of vehicles ... worth the time and effort? I like to think so. I was able to achieve my goals. Was there an off the shelf solution that would have done the same thing? Maybe, maybe not. Milking the last HP or TQ out of a motor is not everyone's cup 'o' tea. What most folks say they want and what they really want are usually quite different. Once the ground fall and low hanging fruit have been exhausted most will not bother with getting the ladder or hot air ballon out to get the choice bits hidden up high :>)
>terms that get thrown around enough that somebody will start to wonder<
And we finally have the answer....
Quote from: wfolarry on May 29, 2009, 05:40:23 PM
:potstir:
With the internet all kinds of information becomes available to any body that wants it [& knows how to find it]. It's what we do with that information that makes it or breaks it for some. Overexhausting, underexhausting or anything in between are terms that get thrown around enough that somebody will start to wonder if their build is optimum. Did I leave anything on the table? Could I have gotten more out of it? Maybe. Spend the money to find out. Don't want to spend it but want a definitive answer? Buy the bike from the guy that's got what you want.[It does happen] As far as exhausts go I can remember back in my Shovelhead days that Cycle Shack mufflers were the best bang for the $$. I think they still are. Not saying they are the best [I don't think any 1 system is best] but you can't go wrong for the money. My favorite pipe is the Thunderheader. Maybe it doesn't make the most power [or maybe it does] but I like the way it sounds. It's in the shed as I have a Propipe on now. I try just about everything once.
As for the valve size question I put a 1.610 in a 124 & made 170hp. [race bike] Another 124 I built with bigger valves [both intake & exhaust] made 170hp too but it will walk away from the other bike on the top end. The throat on the exhaust on the 1st bike is 1.390. A stock TC is 1.375. So did a .015" increase in throat size make all that power or was there some magic involved? :wink: There are a lot of good exhaust systems to choose from now so I would pick a good one, GET A GOOD TUNE, & ride it! The 2hp you lost by not picking the best will never be missed. Time for dinner.
One more thing. On the race bike we have a new pipe custom made by Brian Truesdale. He worked for White Bros. when the E pipe was the hot pipe. He moved back here from the left coast & is making custom pipes. I'll let you know how that works out when I have some facts to report back.
Larry,
I'm not sure you are stirring the pot here. I think that you are saying what an exhaust valve can achieve.. I agree with what you are saying. This is a little different. I'm asking if too much exhaust flow can cause and issue in reference to HDs.. I can see where it might would have little, to no, to bad effect on say a 4 valve short stroke motor but the thing about HD is that they can only be marginally over square and with valves not optimized for performance.
BTW, Left cost is going to pot.. The only true west AHDRA race is in Woodburn..
Max.
Max,
Do you think that a too big exhaust valve can be compensated for with the right exhaust? Or a too small exhaust valve can be compensated for with a longer duration cam? When I port heads I get that exhaust to flow as good as it can & sound good too. I've never had a head that was 'overexhausting' from doing this with stock, 1.6, 1.630 etc. The pipe has too big of an effect. I've seen too many times where 1 guy's build would run great But his buddy who has the same build except for a different exhaust would run like chit. I think this is where a good dyno tuner's experience really pays off. #'s ain't coming up? Lets change the pipe & see what happens.Bam! Now it's working. Show the customer the difference & you know what he says? "I like the way the other pipe looks. Or Sounds. I think I'll keep it." If you're chasing HP because you're a racer or you just have to have it then it pays to test with a few different pipes to see what happens. Look at all the guys at the track with weather stations. Changing the tune on their car depending on the weather. Same thing. Putting in a 1.710 exhaust valve with a 1.90 intake valve would be overexhausting. Unless you were running a turbo. Then it might be the hot ticket. Only 1 way to find out. Test it.
P.S. I ran a Thunderheader on my 80" Evo with a baby cam & it ran great. Some would say it was overexhausted. But they never rode it. :wink:
QuoteThe pipe has too big of an effect. I've seen too many times where 1 guy's build would run great But his buddy who has the same build except for a different exhaust would run like chit.
Thanks for the reply Larry,
We're on the same page... It's the pipe where the exhaust tuning occurs.
Max
On the race bike we have a new pipe custom made by Brian Truesdale. He worked for White Bros. when the E pipe was the hot pipe. He moved back here from the left coast & is making custom pipes. I'll let you know how that works out when I have some facts to report back.
Tell Brian hi from Larry Hardy and have him give me a call 714 282 8936 or shoot his number
thanks for passen it on
Larry
>>It's the pipe where the exhaust tuning occurs.<<
Don't forget to include the port length (back side of valve or seat face to header joint/flange) as part of the total header length.
Now, food for thought:
What part, if any, does the port shape, seat shape, backside of the valve, and the reverse flow characteristics of the exhaust port play in the scavenge process during overlap? Can a port that is efficient for evacuating the cylinder and has high flow rates for outflow suck (pun intended) in a reverse flow situation? Does a good flowing port (static flow bench) always result in one that is efficient when finite amplitude waves enter the picture? How do you account for things like blowback, reversion, short circuit losses, and charge dilution with just flow figures? Can exhaust tuning affect any or all of the previously mentioned?
Does anyone GAS? :>)
We'll disregard cam timing and duration for now ... but if ya want a good exhaust system and your calcultions don't factor this in ... you likely have missed the mark!
A version step.
Yes
No
You don't
Yes,
Only after eating at a Chipotle Mexican food place. Max
>>A version step.<<
Which one? Ver. 1, 2, ... ? Oh, bet you meant a reversion step. Yes, but it can involve even more than that.
OOPS! Pardon me, I think I just over exhausted :>) Anyone got a match?
Those weren't really questions for you, I know you have a good handle on this stuff
What part, if any, does the port shape, seat shape, backside of the valve, and the reverse flow characteristics of the exhaust port play in the scavenge process during overlap? Can a port that is efficient for evacuating the cylinder and has high flow rates for outflow suck (pun intended) in a reverse flow situation? Does a good flowing port (static flow bench) always result in one that is efficient when finite amplitude waves enter the picture? How do you account for things like blowback, reversion, short circuit losses, and charge dilution with just flow figures? Can exhaust tuning affect any or all of the previously mentioned?
Jeess, I thought we were suppose to ask you the questions ED.
I know :rtfb:
there on order. :wink:
I would think that a ex port with "too much" of an AR step would be less responsive to the benefits of a tuned pipe. After all, if the step can partially reflect an undesirable high pressure wave, it will do the same to a desirable low pressure wave.
Lower the short turn and open the throat tooo much, bet you can't get a pipe to correct that.
WFO you ever heard one sounds like it has a flapper inside when flowing exhaust :hyst: It was'nt funny at the time :emsad:
Quote from: hardyheadscom on June 01, 2009, 08:12:27 AM
On the race bike we have a new pipe custom made by Brian Truesdale. He worked for White Bros. when the E pipe was the hot pipe. He moved back here from the left coast & is making custom pipes. I'll let you know how that works out when I have some facts to report back.
Tell Brian hi from Larry Hardy and have him give me a call 714 282 8936 or shoot his number
thanks for passen it on
Larry
I'll pass it on for you.
Quote from: POORBOY on June 01, 2009, 02:50:03 PM
Lower the short turn and open the throat tooo much, bet you can't get a pipe to correct that.
WFO you ever heard one sounds like it has a flapper inside when flowing exhaust :hyst: It was'nt funny at the time :emsad:
I had a set of heads on the bench last year that were done by somebody else that I was checking because the motor wasn't making any power. On the initial test they seemed pretty good so I did a valve job on them & put them back on the bench. This time I didn't put a pipe on the exhaust. Figuring the #'s would be a little lower I proceeded with the test. Without the pipe the port flowed terrible. Did some work to the port to straighten it out & put the heads back on the bike. Bingo! the #'s came right up. if I didn't check the heads without the pipe they would have kept on looking for the problem somewhere else when it was in the heads to begin with.
Quote from: ederdelyi on June 01, 2009, 10:47:57 AM
>>It's the pipe where the exhaust tuning occurs.<<
Don't forget to include the port length (back side of valve or seat face to header joint/flange) as part of the total header length.
Now, food for thought:
What part, if any, does the port shape, seat shape, backside of the valve, and the reverse flow characteristics of the exhaust port play in the scavenge process during overlap? Can a port that is efficient for evacuating the cylinder and has high flow rates for outflow suck (pun intended) in a reverse flow situation? Does a good flowing port (static flow bench) always result in one that is efficient when finite amplitude waves enter the picture? How do you account for things like blowback, reversion, short circuit losses, and charge dilution with just flow figures? Can exhaust tuning affect any or all of the previously mentioned?
Whenever I'm looking at a set of heads I've done I look for problems with the exhaust in the intake ports. You know what I mean :wink:
>>Whenever I'm looking at a set of heads I've done I look for problems with the exhaust in the intake ports. You know what I mean<<
:up: Yep. Reading the "signs" in the ports and chambers can reveal a lot about what's going on. "The Devil is in the details" :>)
You guys are leaving out the main ingredient, Intake to Exhaust percentage,some call it exhaust reversion.
Quote from: POORBOY on June 03, 2009, 08:45:23 PM
You guys are leaving out the main ingredient, Intake to Exhaust percentage,some call it exhaust reversion.
That's not over exhausting that backwards exhausting.. :teeth: Max
Sorry Max, I must'a had another BrainFart,going back to my room
Quote from: POORBOY on June 03, 2009, 08:45:23 PM
You guys are leaving out the main ingredient, Intake to Exhaust percentage,some call it exhaust reversion.
We didn't leave it out. You didn't catch it. Look up.
Borzilla on anything less than a 113
Quote from: POORBOY on June 04, 2009, 04:33:46 AM
Sorry Max, I must'a had another BrainFart,going back to my room
Well,
This thread is dyin' anyway.. We can talk about reversion also... What causes reversion? I figure it's a combination of intake tuning and exhaust tuning (wave) coupled with cam timing.. I'd expect that it's main root source is the exhaust blowing into the intake during overlap.. Would valve sizing have an effect on this issue?? I'd bet, the better flowing the valves at low lift, the worse the problem.. Still I'd say it's a wave tuning issue in both the intake and exhaust...
Quote from: speed limit on June 04, 2009, 05:57:15 AM
Borzilla on anything less than a 113
Don't you mean anything "more" ?
Max
>>What causes reversion? I figure it's a combination of intake tuning and exhaust tuning (wave) coupled with cam timing.. I'd expect that it's main root source is the exhaust blowing into the intake during overlap.. Would valve sizing have an effect on this issue?? I'd bet, the better flowing the valves at low lift, the worse the problem.. Still I'd say it's a wave tuning issue in both the intake and exhaust... <<
That's the basics of it. A mismatch of intake/exhaust tune to cam timing and cylinder pressures and varies with RPM.. The emphasis in active intake and exhaust tuning coupled with VVT schemes on late model cars and motorcycles are schemes to minimize those mismatches and extend the benefits of wave tuning over a broader RPM range. If done correctly, the arguement of TQ vs HP "goes away" as the motor will make power at the bottom as well as the top ... assuming the greenies don't get IC engines banned outright before the technology becomes mainstream!
Reversion, charge dilution, and short circuit losses are all products of these mismatches and cost power as well as fuel efficiency and emissions ... it's those damn details again :>) Active MBT schemes (Subaru and others) are also being used to maximize power and efficiency. Affordable electronics and engine management controls are really our friends and may well be the only thing that will save the IC engine and have it retain any real performance and fuel efficiency. Those that hate change won't like it ... the dinosaurs didn't like change either and look what happened to them :>)
Max, take your pocket watch and slowly swing it back and forth in front of your face and repeat ...
"You are over exhausting",........ "you are over exhausting".
I did that but I musta passed out cuz when I woke up my watch was gone... Max
This is an interesting thread, thanks to all of you for sharing your thoughts.
In one of the latest American Iron Magazine issues there is an article on Harley heads. The article says that in 2007 Harley started leaving out the reversion step in the exhaust. The author states that adding a set of Torque Cones would be beneficial to performance with these heads.
Your opinions please?
It would be a fairly easy & cheap way of gainng some performance if it would work.
Jim
>>Your opinions please?<<
Depends. Might help some drag pipes or other "lookee Lou" exhausts. On others it may do nothing or take something away from a good exhaust system. Blanket statements like you make reference to always bother me. My crystal ball must not have the bandwidth that these "experts" crystal balls seem to have ... maybe if I save my pennies I may be able to get one like theirs!
QuoteThe article says that in 2007 Harley started leaving out the reversion step in the exhaust.
I believe they left the step out of 06s also... The set I have, didn't have them...
QuoteThe author states that adding a set of Torque Cones would be beneficial to performance with these heads.
Maybe if you were over exhausting. My crystal ball is kind of cloudy, I dropped it and it broke... Currently held together with JB weld.. :wink: That's OK, got it cheap off of ebay.. Max
If you are refering to a step below the seat where the casting starts it is still there.
Torque cones, no thanks