Exhaust Poll

Originally Posted by chii370

Ive seen plenty of cars ive had buddies build that fell into the DERP BIGGER MEANS BETTER retard mindset and went from 2.5 to 3 or even bigger. And then gained absolutely nothing on the dyno. There IS a point when its too much. and FI 370's arent exactly a popular choice as we all know, so metric a55tons of options are not available, nor have they been around for 10+ years for tuner experience. So its hard to say what that limit really is. But yeah, im sure at 8000 RPM with a tt setup pushing tons of HP WOULD benifit, but at any other time, it doesnt, especially NA cars. its not just about flow restriction, i wish people would get that **** out of their heads. its about FLOW VELOCITY. you can have MORE, LESS RESTRICTED exhaust through a 2.5 on a motor than a 3!!! OMG HOW you ask. well, allow me to give you a physics lesson. Exhaust comes out in pulses, not a constant stream of air. ahead of the pulse is a high pressure zone, behind is a low pressure zone. each pulse "pulls" the pulse behind it through the pipe. Now if you have pipes that are too big, the pulse will esentially use too much "energy" and start to slow down and instead curl in an outward motion toward the pipe walls. this does 2 things. causes turbulence, and causes a possitive pressure against pressure still exiting the engine, which can raise the pressure directly outside the exhaust valves. If this happens you can be robbed of power by less exhaust exiting the cylinders so less new air and fuel can enter or maf will be incorrect, and more effort to "push" the exhaust out the pipe. this also causes the infamous "rasp" everyone talks about. its NOT a noise the engine makes. Its caused by a drop in exhaust velocity somewhere along the pipe, which creates turbulence. this breaks up the nice individual exhaust tone "puffs" you hear and exits the back in a nasty sounding wheezing noise. havent you made the corrolation between setups that rasp, and the fact that MOST of them are the LEAST restrictive? or have LTH? or HFC or cat deletes? its not simply a "sound the engine makes" EVERY CAR can make that sound. start watching vids for aftermarket exhausts on other cars on youtube. like a tiberon or something. one setup will sound great, and the next will rasp like hell.