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Old 07-29-2009, 01:02 AM   #22 (permalink)
ih freak
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Originally Posted by ATaylorRacing View Post
Here is my take...with 35 years of drag racing street driven cars:

If your car does not require premium and the timing is stock you can actually get worse mpg with higher octane, The higher the octane, the slower it burns....a lot of cars drag raced with premium fuel will actually run slower and have less power. Just run reg if your car calls for it.

As far as running 87 in a car that requires 92.....on my 05 SRT4 Neon (230 hp 2.4 turbo bone stock) I WAS running 87 when I first got it. On my 80 mile loop that I use for mpg comparisons I got only 27 at 55-60mph while it was rated at 31. I even fill up at the same pump and put it on slow speed till it clicks off...not a penny more...then with 92 oct I then got the 31. That car now gets 32.8 with a stage 3 set up that developes 285 hp!

As far as 10% ethenol is might get as bad as 20% WORSE mpg since more fuel is needed to obtain the same driving parimeters. I read in a magazine last year that E85 can be as bad as 27% worse than straight gas and on my flex fuel 01 Caravan it did get @ 25% worse on E85 compared back to back with reg 87 oct gas.

Guys that convert their drag race cars to alcohol must increase the jetting in their carbs by about double for the same power levels, but then they benefit from a cooler running motor and can mofify them to run more compression and or boost.
I agree. I have a 95 volvo 850 wagon. If I run 87 in it in a matter of minutes I will stall at every stoplight or stop sign. If it calls for 87 run 87. If it calls for 89 run 89. I work in a small engine shop and we have seen a lot of engines vapor locking on hot days due to the lower boiling point of ethanol.
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