Quote:
Originally Posted by ta man
I tested a theory a few years ago on my car. The exhaust at the time consisted of 3 inch X pipe, cone reducers to 2.5 ultraflows and 2.5 inch tailpipes. Just by removing the tailpipes the car picked just over one tenth and 1 mph in the quarter mile. This was on a well tuned and tested car. Many at the time who were aware of the test thought there would be zero gains. app 550 to 570hp engine at the time.
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My JR Headers had 4 inch collectors and 2" equal length pipes before the collectors. The pipes were also positioned in a flat collector design. Maybe some remember that JR Flat Collector design.
From the 4" collectors I ran several feet of 4" tubing to custom reducers that fed the inlets of 3" Walker "long length" mufflers.
The pipes were retained on the vehicle using Marmon Flanges and Marmon Clamps. So in about 10 seconds I could swing the head pipes out of the way and have open collectors or drop the whole down pipe system (with the mufflers hanging still in place).
All that being said, I agree that even with 4" collectors and pipes to the mufflers, the car always was faster with the headers open.
Tom V.
I forgot to mention that I had down-turns immediately after the mufflers, no tailpipes.
So the difference in performance was not with the head pipe diameters or headers but totally in the Muffler
design from Walker. That is why the car has Tom Hand's VOE mufflers on the car today. I do stuff for reasons
as did Pontiac Engineers when they designed the VOE Mufflers many years ago. They work.