Quote:
Originally Posted by Domman56
I know it's just a V6 stang but have you ever tried running 91 octane and if so does it hurt/help mileage?
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In short, it hurts mileage. I have tried running 91 octane with HyperTech's 91 octane performance tune in the ecu. Low-end torque was noticeably better by "seat-of-the-pants" dynamometer. Fuel economy was lower due to lower energy content in higher octane fuel. Without the HyperTech 91 octane performance tune, performance would have been the same as with 87 octane fuel with the same (or even
more) reduction in fuel economy. See my fuel log for the Summer months of 2010 for more details. So far, my best "streak" has been 4 consecutive fill-ups over 31MPG during the Summer. I've done it 3 times, so far.
My next fill-up may change that best streak to 5 consecutive fill-ups over 31MPG, if I'm lucky...
