4" exhaust?
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From: Atlanta
Inline is using 4 inch i think. but man unless you are usuing a huge turbo then you wanna stay 3 inch. you never wanna go TOO BIG. You want the back pressure sometimes. back pressure will give you tq. Tq is something we desperately need in out little cars.
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From: SLC, UT
Originally Posted by spectacle,Sep 22 2009, 08:42 AM
You talking 4 inch with a dump before or after the axle? Running a 4 incher under the axle is going to be fun to fab up lol
I wanna see it!This guy doesn't care about torque below 6000 rpm. He's already making 563whp. He is going for peak HP.
That being said, we have little 4 bangers. I don't know if the benefit of a 4 inch exhaust outweighs the silly amount of noise that will be coming out of it. LOUD! Besides, what is the diameter of the manifold collector pipe? If it's 2.5", then your gains from the 4 inch exhaust will be minimal because I can't really imagine the exhaust gas velocity increase will go up that much, and you'll lose drivability because low rpm torque should decrease.
Now, if the collector and the downpipe are 4", go for it. I love seeing these builds. It's kind of inspiring, ain't it?
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Originally Posted by CourageOO7,Sep 22 2009, 07:37 AM
4 inch side exit, anyone? I wanna see it!
This guy doesn't care about torque below 6000 rpm. He's already making 563whp. He is going for peak HP.
That being said, we have little 4 bangers. I don't know if the benefit of a 4 inch exhaust outweighs the silly amount of noise that will be coming out of it. LOUD! Besides, what is the diameter of the manifold collector pipe? If it's 2.5", then your gains from the 4 inch exhaust will be minimal because I can't really imagine the exhaust gas velocity increase will go up that much, and you'll lose drivability because low rpm torque should decrease.
Now, if the collector and the downpipe are 4", go for it. I love seeing these builds. It's kind of inspiring, ain't it?
I wanna see it!This guy doesn't care about torque below 6000 rpm. He's already making 563whp. He is going for peak HP.
That being said, we have little 4 bangers. I don't know if the benefit of a 4 inch exhaust outweighs the silly amount of noise that will be coming out of it. LOUD! Besides, what is the diameter of the manifold collector pipe? If it's 2.5", then your gains from the 4 inch exhaust will be minimal because I can't really imagine the exhaust gas velocity increase will go up that much, and you'll lose drivability because low rpm torque should decrease.
Now, if the collector and the downpipe are 4", go for it. I love seeing these builds. It's kind of inspiring, ain't it?
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You want the back pressure sometimes. back pressure will give you tq. Tq is something we desperately need in out little cars.
Your well into the area where 4" will see gains, I make right at 600whp and I'm running a 4"
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From: Atlanta
Originally Posted by Momentum,Sep 22 2009, 07:54 AM
This is one of the biggest automotive myths there is. With a turbo car there is no point in the RPM range that having back pressure post turbine is a good thing PERIOD. That doesn't mean that bigger is always better though, there is an optimal exhaust size to get the lowest possible pressure. For example a 6" tube on a 400hp car is going to allow the exhaust gas to rapidly expand, cool, and lose velocity which in turn will create back pressure. Or a 2" exhaust on a 400hp car will just create back pressure by restricting flow.
Your well into the area where 4" will see gains, I make right at 600whp and I'm running a 4"
Your well into the area where 4" will see gains, I make right at 600whp and I'm running a 4"
