[TJay74]

Originally Posted by Mcmillion

I have just started logging my car today. Just curious what was the max intake manifold pressure psi you saw and your max throttle position. My car would not get over 83% the max psi I saw was 13.5.

Just to confirm yours and TJays findings on octane I also had 0 KR, running 91 with 3 gallons of e80.

The OEM timing map for the GM 6.2L engines is pretty aggressive from the factory. While they can run on 91, they really need 93 and depending on how hot it is outside may even need more octane to keep KR at 0 or the addition of 2-3 gallons of E85.

83% is the correct WOT reading in HPT's.

Once you add say 3 gallons of E85 to the tank you need to make sure in the future you only add 15% of the amount of fuel it takes to get back to full otherwise if you continue to add 3 gallons you will eventually increase the E85 mix well above the E15 range.

So as an example, if the 1st time you add 3 gallons of E85, you are now at E15. If you take the tank to half on the gauge it will roughly take 9-10 gallons to fill up again, you dont want to add more than 1.5 gallons of E85 to keep the mix at E15.

In order to keep the mix right you will need to know roughly how many gallons of gas it will take to get back to full again.