Originally Posted by rcreechssr
With the new computer controlled engines, it would appear that octane rating is not as critical to prevent pre-ignition as in older engines. These engines will self adjust and run on 87 octane. However, as stated by others in this thread, you will lose some performance and in my experience some gas mileage (1-2mpg).
Now the economics. 92 octane is generally $.20-.25 more than 87 octane. My logic says that in a typical 20 gal. fill up, I'll pay roughly $4.00-$6.00 more per tank. In my opinion, that aint bad for a tank of higher performance, and better gas mileage. Just a thought.
while computers in automobiles do self adjust to run on lower octane gas, thats whats hurting your performance
. they cut back the spark timing to prevent detonation (combustion cycle preignition) which means you dont start the combustion cycle till later in the rotation of the motor which means you arent reaching your full power potential
i spend 45 bucks to fill my car up (roughly) 14 gal tank, i fill up with 10-11 gal (cus i dont run my car down past 1/4 tank cus it can be detrimental to performance and the fuel pump). as ive stated before, i wont put 87 in my car. its a rare occasion that i'll even run 91 or... dare i say it 89.
93 for me baby