exhaust question Options

[eldrewado]

So I made my own exhaust on my GT. After the stock resonator i upped the diameter of the pipe to 2.25 then it goes into a long glasspack muffler then a downpipe just before the rear axle. I seem to be getting better gas mileage, so i want to keep my flow through design, but its so LOUD. I ordered 2 vibrant resonators I heard one is good and two is better and they are flow through. The question is....Should I build the system resonator-resonator-glasspack,
resonator-glasspack-resonator, glasspack-resonator-resonator, or just leave the glasspack out?

[Special_Edy]

Everything Glacobar I agree with, but Id like to add that-

Resonance plays a major part in exhaust design. Just like intake manifold runners, the exhaust system experiences pulses and these pulses can either resonate back into the cylinder or resonate out towards the tailpipe. This includes both sound and the pressure waves from the exhaust pulses.
This leads us to scavenging. Scavenging occurs when a high pressure exhaust pulse leaves the cylinder and travels down the exhaust pipe and header. The high pressure pulse leaves a low pressure void behind it, so if the wave frequency(relative to rpm) matches the pipe length and width the low pressure part of the pulses will actually suck the exhaust gasses out of the cylinder on the next pulse. If the pipe is too wide in diameter the velocity of the exhaust will be too slow for effective scavenging. If the pipe is longer it will have a harmonic better suited for low rpm so shorter pipe lengths will better benefit high rpms.

The optimal size and length of the exhaust fluctuates with rpm. Engines moving at low speed produce more torque from longer headers and smaller pipe diameter(until a certian point) but this exhaust will restrict the engine at high rpms. Shortening the header pipe and increasing its diameter(to a point) will increase the torque at higher rpms, though this exhaust will flow too much for low rpms. So you have to make a compromise between torque(drivability) at low speeds and torque(horsepower) at high rpms. This is part of why most engines seem to produce so little horsepower from the factory. The engineers had to decide between high rpm performance or low rpm performance on many different engine components.

This post has been edited by Special_Edy: Dec 10, 2012 - 6:37 PM