[joemosfet]

Originally Posted by Whis

Woah what? How does this help?

How does running lower octane fuel help? It's cheaper, I guess...

Just to be clear, extra octane does not increase power.

Octane rating is simply a descriptor for the gasoline's ability to self-detonate at certain temperatures and pressures.

In gasoline engines, detonation is a violent explosive reaction, not something we want. Rather we want the fuel to burn and expand gasses at a predictable rate.

Engines that have higher internal temperatures, or engines that have high compression, or engines that advance the timing to get a bit more power (max compression at top dead center) require higher octane fuel.

Because of our high altitude, and lower air pressures, the internal cylinder pressure is reduced (compared to our friends at sea level). There is even less chance of detonation allowing us to buy lower octane fuel. Or increase boost. Or advance timing. (Or a combination of the above.)

Oh, additionally, the LT1 features direct injection, where it can already run higher compression because there is no fuel in the chamber to pre-detonate. The injectors can spray at a controlled rate, even after the valves have closed and pressure is building. This is much like how a diesel works, but a diesel doesn't even need spark plugs. The heat and pressure in the cylinder are enough to ignite the diesel's direct injection spray. Diesel has an extremely low octane rating.