Quote:
Originally Posted by Tom Vaught
I was going thru some old files and found this testing (performed by the University of Northwestern Ohio some years ago).
They did a Test of EQUAL VS UNEQUAL LENGTH HEADERS on a Engine Dyno.
They ran at Street RPM test points vs Race RPM points.
The engine was a 525 CID Big Block Chevy but the comparison is valid.
This would cover the most common Pontiac Displacements (minus the 540/565 sized ones).
Engine rpm: The test points were in 100 rpm increments, from 3000 to 6000 rpm.
I am not going to post the dyno sheet as it was copied to an excel file and can't easily be posted.
They showed at 4500 rpm the torque difference was 715 vs 723 or 8 lbs/ft difference
The HP was 612.6 vs 619.5 or 6.9 horsepower difference. Unequal being actually BETTER.
They showed at 6000 rpm the torque difference was 610 vs 636 or 26 lbs/ft difference
The HP was 696.9 vs 726.6 or 29.7 horsepower difference. Unequal being actually BETTER, again.
So Stan, what is going on here? (Course it WAS a Big Block Chebby Engine).
Tom V.
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Tom, Rob McCabe is right up the street from me. Getting older now but still building headers as far as I know.
http://www.mccaberacing.com/contact-us.html
I've worked beside him while he was building headers for some of the Pro Mod cars I was painting. Guy is a wealth of knowledge. Matter of fact before he settled here in AZ permanently he worked full time for the Nascar teams. His headers were part of a package that was winning so many races at the time that other teams tried to hire him, find trade secrets etc... and became a real cut throat deal. In the end he got tired of all the traveling, retired from Nascar and now builds headers for anything. Some of the best work I've ever seen. Next time I'm up there I'll pick his brain about this subject. I'd bet he could explain it to me in a few sentences what will work and what won't.