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      10-06-2012, 05:28 AM   #5
LarThaL's Avatar

Drives: 2011 M3
Join Date: Apr 2011
Location: West Springfield, MA

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Originally Posted by GIdriver View Post
So I will go to a 1/2 mile event in December and since I have availability of 100 octane Sunoco race fuel was wondering if it will make any difference going higher than 93 AKI. I'm hoping for a 130-135mph top speed at the 1/2 mile.

As my signature says, I have the ESS Akra Evo tune. ESS told me that the tuning file is adaptive from 91 to 95 AKI. From what I've read our cars stock won't gain much above 95-96 AKI.

My questions are (given my tune):

1. Will going above 95 will hurt the engine?
2. Will going above 95 will hurt performance in any way?
3. How about meth?

Thanks in advance.

PS: I know there will be much more faster cars at the event (for example there will be two Alpha 12 GTR's . Going just to enjoy my car in a safe environment and have fun with some friends.
This all depends on the ECU programming. Here's the "basic 101" version of how it works:

The fuel octane content will affect the oxygen content of the exhaust gases. This translates to voltage changes from your oxygen sensors. These signals are sent back to the ECU. If your ECU program allows for it, it will advance the ignition timing resulting in more power. A more sophisticated ECU program (which one would hope is in a high performance car) will be based on increasing detonation thresholds as the octane increases. It will sense the changed output from the oxygen sensor when high octane fuel is used, interpret this as a higher detonation threshold, and allow for ignition timing advance. This creates more power.

There are other factors, but this is the bulk of it. Most of the high end european performers will make more power up to about 95-96 octane. Beyond this, there is no more timing advance regardless of the change in oxygen sensor voltage output.
Audi S6 * Audi S3 * Porsche Cayman GTS
--Former BMW M3 owner