Good post Tony. We can all beneft from your true real world first hand experience.

One thing to add in regards to Rams Horn manifolds, they are not all created equal. The stock 2-1/2" Corvette style are said to be about 66% as good as headers on a mild SBC. The more radical the motor, the more you will benefit from headers, again, it's the flow in and flow out that Tony discussed. Some people are porting the 'vette rams horn and getting within 10% of headers, but those ported manifolds cost as much or more than a set of headers. Why? Well in certain drag racing classes stock, means running stock parts. But the classes allow modifying the stock parts, thus you end up with hhigh dollar stock manifold modifications.

Here is a link to a company that sells stock and modified Rams Horn manifolds, as well as late 60's "log" style manifolds.

http://www.castheads.com/faqs_exhaust_manifolds.php

And here is some actual data posted in regards to a '72 LT1 motor, rams horn vs. headers.:

http://forums.corvetteforum.com/c3-tech-performance/809890-rams-horn-manifolds-vs-headers.html
The difference between a fully ported set of 2.5" dia rams horns and Hooker Super Comp 1.75" headers was about 10% of my power on my 1972 LT-1 motor during a dyno test of the motor (394HP manifolds/426HP Hookers.) The testing was done with a set of DynoMax Ultra Flow 2.5" mufflers on a simulated exhaust system. The difference at the Drags [email protected] MPH with rams horns (I had a lot of porting labor in them and broke over $90 of carbide burrs porting them, they were better than Brezinski manifolds) and 12.28@117 MPH with the Hookers (both runs through the mufflers.)

Last edited by Hot Rod John; 11/28/2010 4:59 PM.
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