Header Theory by Vince Roman from Burns @ PRI

General engine tech -- Drag Racing to Circle Track

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induction apprentice
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Re: Header Theory by Vince Roman from Burns @ PRI

Post by induction apprentice » Sun Dec 09, 2018 3:59 am

proheader wrote:
Sat Dec 01, 2018 7:19 pm
Why such the concern about equal length tubes?? EGt proves sometimes not all holes burn the same?? How about considering exhaust pulse collector timing first over length??

Proheader
IMO: you seem to make a lot of assumptions in this statement including egt readings are consistant enough to prove something.

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Re: Header Theory by Vince Roman from Burns @ PRI

Post by hoffman900 » Sun Dec 09, 2018 7:50 am

induction apprentice wrote:
Sun Dec 09, 2018 3:59 am
proheader wrote:
Sat Dec 01, 2018 7:19 pm
Why such the concern about equal length tubes?? EGt proves sometimes not all holes burn the same?? How about considering exhaust pulse collector timing first over length??

Proheader
IMO: you seem to make a lot of assumptions in this statement including egt readings are consistant enough to prove something.
Judging by NASCAR utilizing different advancement curves for each cylinder, and this on a purpose built platform that likely has better cylinder-cylinder variation than a production based engine, he might know something ;) ...

Pretty sure this is him:
http://www.proheadersystems.com/default.asp
-Bob

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Re: Header Theory by Vince Roman from Burns @ PRI

Post by Firedome8 » Sun Dec 09, 2018 12:23 pm

Are applications that require a broader power curve better served with unequal length primary pipes?

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Re: Header Theory by Vince Roman from Burns @ PRI

Post by Newold1 » Sun Dec 09, 2018 12:40 pm

From my limited knowledge base 4 to 2 to 1 stepped merge equal length primary headers can but in V-8's uneven length, I don't think so.
The Older I Get, The Dumber I Get :wink:

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Re: Header Theory by Vince Roman from Burns @ PRI

Post by swampbuggy » Sun Dec 09, 2018 12:46 pm

Firedome8, what would cause you to ask that question, or why would you ask that question ?? :?

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Re: Header Theory by Vince Roman from Burns @ PRI

Post by j-c-c » Sun Dec 09, 2018 1:19 pm

I see much attention here given to equal length here, but since we are not talking straight pipe tuning, and I don't see why anyone would expect uniform crossectional mass/velocity flow in a bent pipe, it seems like an artificial holy grail target.

But then I liked the guitar tuner method posted earlier. :mrgreen:

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Re: Header Theory by Vince Roman from Burns @ PRI

Post by Newold1 » Sun Dec 09, 2018 1:56 pm

Don't think equal length is holy grail but if you look at almost all forms of WINNING race cars, equal length primary header systems seem to pop up every time. I'll go with equal length until successful usage and results shows me otherwise. It's the Missourian in me ,"SHOW ME"! :wink:
The Older I Get, The Dumber I Get :wink:

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Re: Header Theory by Vince Roman from Burns @ PRI

Post by j-c-c » Sun Dec 09, 2018 2:03 pm

Newold1 wrote:
Sun Dec 09, 2018 1:56 pm
Don't think equal length is holy grail but if you look at almost all forms of WINNING race cars, equal length primary header systems seem to pop up every time. I'll go with equal length until successful usage and results shows me otherwise. It's the Missourian in me ,"SHOW ME"! :wink:
This topic is admittedly, above my pay grade, maybe I should have stated "effective equal length" is the goal rather then just taking a single measurement?

Missouri is also in my DNA. :mrgreen:

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Re: Header Theory by Vince Roman from Burns @ PRI

Post by MadBill » Sun Dec 09, 2018 2:11 pm

DV presents some very interesting data re individual primary lengths in his 2nd edition BBC book. Pressure transducers figure heavily.
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Re: Header Theory by Vince Roman from Burns @ PRI

Post by hoffman900 » Sun Dec 09, 2018 5:32 pm

:twisted: Going back to Calvin’s point, we’re talking an inch or two at the most unequal length. How much variation is on the intake side of say a BBC port from valve seat to plenum?

I think I too would give up an inch or two if it meant increasing radius size, which may allow you to reduce pipe diameter for a given hp.

David’s comment about NASCAR headers being wrong in another thread is interesting, especially considering all the instrumentation, engineers, and testing involved... :?

Would like him to elaborate on that more, but color me skeptical..
-Bob

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Re: Header Theory by Vince Roman from Burns @ PRI

Post by David Vizard » Sun Dec 09, 2018 5:39 pm

hoffman900 wrote:
Sun Dec 09, 2018 5:32 pm
Going back to Calvin’s point, we’re talking an inch or two at the most unequal length. How much variation is on the intake side of say a BBC port from valve seat to plenum?

I think I too would give up an inch or two if it meant increasing radius size, which may allow you to reduce pipe diameter for a given hp.

David’s comment about NASCAR headers being wrong in another thread is interesting, especially considering all the instrumentation, engineers, and testing involved... :?

Would like him to elaborate on that more, but color me skeptical..
There are several pages on the tests we did at the University of Northwestern Ohio (NHO). If that does not sow the seeds of doubt as to whether or not current NASCAR headers are right or wrong nothing will.
DV
David Vizard Small Group Performance Seminars - held about every 2 months. My shop or yours. Contact for seminar deails - davidvizardseminar@gmail.com for details.

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Re: Header Theory by Vince Roman from Burns @ PRI

Post by Firedome8 » Sun Dec 09, 2018 5:45 pm

swampbuggy wrote:
Sun Dec 09, 2018 12:46 pm
Firedome8, what would cause you to ask that question, or why would you ask that question ?? :?
If each cylinder has a different resonant frequency how would that effect the engine output ?

( resonant frequency being tq. Peak ? )

Just asking questions, exhaust science is interesting to me.

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Re: Header Theory by Vince Roman from Burns @ PRI

Post by swampbuggy » Sun Dec 09, 2018 8:45 pm

Gotcha Firedome8, If a V-8 engine was as close to PERFECT in design as mechanically possible i think we can agree that all parts and dimensions for each cylinder ( intake runner, intake port, valve size, port flow/shape, piston crown/shape, cc's of combustion chamber/shape, should be as close to identical to each other as possible. If this was the case, which it usually is NOT, each header primary pipe would want to be equal length one to another. I guess it is possible to change the primary length on a certain cylinder in an attempt to correct an imbalance on the intake side of the cyl. head :?: :?: Mark H.

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Re: Header Theory by Vince Roman from Burns @ PRI

Post by hoffman900 » Sun Dec 09, 2018 9:53 pm

David Vizard wrote:
Sun Dec 09, 2018 5:39 pm
hoffman900 wrote:
Sun Dec 09, 2018 5:32 pm
Going back to Calvin’s point, we’re talking an inch or two at the most unequal length. How much variation is on the intake side of say a BBC port from valve seat to plenum?

I think I too would give up an inch or two if it meant increasing radius size, which may allow you to reduce pipe diameter for a given hp.

David’s comment about NASCAR headers being wrong in another thread is interesting, especially considering all the instrumentation, engineers, and testing involved... :?

Would like him to elaborate on that more, but color me skeptical..
There are several pages on the tests we did at the University of Northwestern Ohio (NHO). If that does not sow the seeds of doubt as to whether or not current NASCAR headers are right or wrong nothing will.
DV
Is that the one that shows the greatest depression at overlap?
-Bob

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Re: Header Theory by Vince Roman from Burns @ PRI

Post by David Vizard » Sun Dec 09, 2018 10:47 pm

swampbuggy wrote:
Sun Dec 09, 2018 8:45 pm
Gotcha Firedome8, If a V-8 engine was as close to PERFECT in design as mechanically possible i think we can agree that all parts and dimensions for each cylinder ( intake runner, intake port, valve size, port flow/shape, piston crown/shape, cc's of combustion chamber/shape, should be as close to identical to each other as possible. If this was the case, which it usually is NOT, each header primary pipe would want to be equal length one to another. I guess it is possible to change the primary length on a certain cylinder in an attempt to correct an imbalance on the intake side of the cyl. head :?: :?: Mark H.
It still would not want even close to identical lengths!!!!!!

DV
David Vizard Small Group Performance Seminars - held about every 2 months. My shop or yours. Contact for seminar deails - davidvizardseminar@gmail.com for details.

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