Quote:
Originally Posted by Clipdat
How does it lose hp?
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Octane rating is really a measure of how resistant to combustion the fuel is. I guess the theory of it losing power on 100 octane is that the fuel is more resistant to burning, so not all of the fuel burns and you don't get the full power out of the charge. Meanwhile on 91, your getting the same amount of fuel and roughly the same energy content except ALL of it is burning creating power.
The advantage of higher octane is you can run a higher compression ratio without knocking (detonation, which damages your engine) which is thermodynamically more efficient resulting in a power gain. If your engine isn't tuned to run higher octane you're just throwing money away and in
some cases, you may be losing power.
I don't know if my first paragraph holds true for our cars, that's something that will have to be tested, but the idea is sound. If your car isn't tuned for higher octane, it won't do much other than lighten your wallet.
If the extra $8 a tank is worth the psychological benefits who am I to stop you? If you're actually trying to gain measurable speed for competition that's what practice sessions are for, although you'd probably get more time out of tire pressure adjustments or playing with your driving technique.