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Old 12-02-2008, 06:31 PM   #11
Porscheectomy
 
Join Date: Mar 2006
Location: Seattle Area
Posts: 3,011
Quote:
Originally Posted by Adam
I think you're getting the compression ratio mixed up with the air/fuel ratio. An 11:1 air/fuel mixture is extremely rich and the engine would run very poorly. Optimum A/F mixture is around 14.7:1. Eslai, you should definately get a tune done, you'd probably pick up a nice amount of hp and improve the curve even more as you suspected. The computer doesn't richen up the A/F mixture if you run low octane, it just pulls timing so the 91 oct gas isn't why your A/F is rich. Your engine is definately not running at it's peak at 12.5:1
Nope, at full throttle, the optimum power is made at about 12:1-12.5:1 AFR. Stoic is good for fuel efficiency at lower loads, but there's more power at more rich mixtures due to flame front speeds and the inefficiency of combustion.

Last edited by blue2000s; 12-02-2008 at 06:34 PM.
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