This might be a silly question but, aren't big exhaust lines supposed to free up the engine at high Rpm but not help building up torque at low Rpm?
What are the results of a free'd exhaust line on a stock motor?
thanks for your answers.

Marc

My personal feeling is that any loss of torque at low RPM due to enlarging exhaust ports and pipes will be minimal. At low RPM, the inertial "scavenging" effects are small, so if you eliminate them by putting on a big exhaust system that just dumps to atmospheric pressure faster and eliminates resonance, you've only eliminated a small effect. The net gain of better breathing at higher RPM offsets it.

As a data point, Dan and I have a mutual friend who once went hog-wild in porting a set of heads for a 273. HUGE exhaust ports, pretty much to the limit of the castings and the conventional wisdom was that he would have lost a good bit of low end. When it was all put together, it had plenty of low end- not significantly or noticeably different than before. There were a lot of other changes too so its not a direct comparison. But it is a data point.

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