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  #9 (permalink)   Check out my garage 
Old November 17th, 2007, 02:58 PM
Ice78Transam Ice78Transam is offline
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Quote:
Originally Posted by njn63 View Post
Resonance. What basically happens is at certain RPM's the runner length will be perfect and create an actual mild positive pressure... that's the best way I can summarize a 274 page book in a sentence but yeah, a lot of science behind optimum runner length.

Excellent book on this subject:
Amazon.com: Scientific Design of Exhaust & Intake Systems (Engineering and Performance): Books: Philip H. Smith,John C. Morrison


Thats exactly right, Check out AEMPOWER.COM and look at the "How the V2 works" demonstration, it does a pretty good job conceptualizing the air pressure/velocity thing. Wavelengths change as RPMs change. Long runners typically produce better high-rpm performance, whereas shorter runners produce better torque and throttle response. (Almost sure i'm right on all that.)
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