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Old 07-14-2012, 09:59 AM   #42
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Originally Posted by dyn085 View Post
Bernoulli's Priciple will give you some insight. An engine is just an oversized air's not that there's more air flow, just that the velocity changes. Temperature, pressure, and velocity go hand in hand. Your header was smaller piping and was high temp, so velocity was high. In the 2.5", it had more room and time to cool, so velocity slowed. You can only flow out the same amount that flows in.

There's so much more to it, but thats a quick overview.
This decrease in velocity will slow the gasses from exiting the exhaust , which should cause pressure to increase slightly.
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