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      03-23-2011, 10:03 AM   #52
Ilma
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Quote:
Originally Posted by Mike@N54Tuning.com View Post
The test here was holding everything constant including boost at 14.5psi tapering to 12 psi at redline, using 91 octane, and determining if any CPS offset could produce a consistent drop free curve. The testing showed even extreme CPS offsets couldn't which contradicts popular the discussions and theory from a few weeks back. If you look at the 13psi curves they were almost as strong on 91 octane with and without a small offset.
Mike

Thanks for confirming what I am saying........

14.5 psi on 91 octane is a recipe for knock.

I think that to stay relatively knock free, you have to be in the zone of correct boost with correct timing offset which maxes out the timing curve to just below the knock point and of course, appropriate octane for your boost.

That's where the tuning skill comes into play.

That is probably why the 13 psi curves look better on 91 octane than the 14.5 psi ones do.

You just can't keep feeding more and more boost on crappy octane without changing anything else and still expect to make knock-free power. Offsetting timing on 91 octane does not appear to be enough to compensate for the higher combustion temperatures at 14.5 psi.

It's not an insult.....it's just physics.

Last edited by Ilma; 03-23-2011 at 12:26 PM..
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