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Old 10-22-2022, 12:28 PM   #7 (permalink)
Blacktree
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The Prius Experiment - '07 Toyota Prius Base
90 day: 58.52 mpg (US)
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Quote:
Originally Posted by XCRN View Post
So instead of changing the headers, can I add a restriction further up the system, or does it not work like that?
I don't think the problem is with restriction, or backpressure, or whatever. The problem is the pipe diameter. The larger diameter primaries will reduce the exhaust velocity, which in turn weakens the scavenging effect. And as a result, it reduces low-end torque and part-throttle fuel economy.

Think about how you tune intake runners. Long thin runners are better for low-end torque, and short fat ones are better for high RPM breathing. Exhaust tuning is similar.

Long story short, you need smaller headers.
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Last edited by Blacktree; 10-22-2022 at 12:34 PM..
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