Re: 89 octane good, 92 octane not??
A lot of confusion stems from the general misunderstanding of what the octane rating actually means. Basically, the higher the octane, the more suppressed the fuels tendency to ignite without spark. Running an octane level that is higher than what the engine is designed for can hurt performance slightly because the burn is slowed, which causes less energy to be used during the powerstroke. By the time the charge has burned completely, the piston is already on its upward stroke, and the charge is wasted in the exhaust. If you take an engine and raise compression, advance spark, or artificially aspirate (turbo, supercharge, nitrous) then you need higher octane. All the octane levels have the same detergents and additives, so it is just the octane itself that is different. There are some automobiles that actively monitor detonation and advance or retard ignition timing, so using high octane fuel in those applications works because the computer will advance the parameters to accomodate the fuel, but that is in the higher end vehicles. It is proven fact, if the motor is designed and calls for 87 octane, that is what you should use. Gas costs enough as it is, we don't need to waste money even more. If you use the lowest octane fuel you can that prevents or stops pinging (pre-ignition), then that is all you need.
