| wparsons |
07-07-2016 01:34 PM |
Quote:
Originally Posted by KoolBRZ
(Post 2698830)
Too much air no, too much velocity, maybe. Valve timing controls the flow of air and fuel through the cylinder. Air Intake and exhaust restrictions affect the velocity of that flow. Remove some of the exhaust restriction and you change the velocity of flow through the cylinder. Before I complicate things with AVCS valve timing, Injector angles and other complicated stuff, answer me this, how does your car sound now? Is it more brassy sounding, like a trumpet? Or is it more brrrrrraaaaappppppp'y? There is a happy medium between the two which makes the most power. The only way to make sure, is to use tunes ranging from too little AVCS advance to too much advance. The tune between brassy and brrrrrraaaaappppppp'y is the one making the most power. Then the challenge is making the same sound throughout all loads and rpms.
Chances are if your exhaust has changed your restriction too much, your car will sound more brassy, and have less low end torque under medium to heavy loads. If this is happening, contact whoever made your tune and see if they will adjust it for you.
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Removing restrictions too far (most common from too large of a diameter exhaust) will typically give lower exhaust velocity, not higher. There's a sweet spot for velocity for good scavenging (and maximum power).
On a turbo car, the turbo itself is much more of a restriction than anything after it, so the best exhaust is typically the one that has the least restriction possible.
On a supercharged car you can still have benefits from scavenging, but it's not as important.
As for the original question, going to a 3" front pipe isn't going to change overall flow/velocity much since it still has to go through the 2.5" Q300 to get out. That said, testing shows that a good 3" exhaust will make more power than a good 2.5" exhaust, even N/A, on these cars. |
