Rosewood EAII Fairmont 02/90. MPFI 3.9L (formerly CFI), 4spd BTR Auto. Skyline geared 3.45g open center 28 spline 4 pinion differential & axles. 2 1/2" Cat Back Exhaust. King Super Low Springs. Sound: Equalization and amplification by Clarion; Head unit by Sony, Front, Rears and Sub by Pioneer. Planned mods - t5, Extractors, Painting Grey Strips and new front and rear bar.
What a load of shite. As if my car I6 needs a 3 inch system.
"Unfortunately, we know of no accurate way to calculate optimal exhaust pipe diameter. This is mainly due to the random nature of an exhaust system -- things like bends or kinks in the piping, temperature fluctuations, differences in muffler design, and the lot, make selecting a pipe diameter little more than a guessing game."
Originally Posted by JC
Good read - makes a lot of sense too. So now can anyone explain why smaller diameter primaries give better low down torque than larger diameter primaries? No? Me too!
According to the article. A pipe too large will allow the exhuast gas to cool down too quick and loose velocity. At low RPMs where the gas is travelling slower, this could have a negative impact such as loss of torque. Smaller pipe could maintain exhaust gas velocity at lower RPM hence produce better "power". However at high RPMs the gas is obviously travelling much faster hence larger pipes are more beneficial?
At least that is how I have interpreted it from this article.
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