93 octane gas only?

[JackG]

Originally Posted by Peer

Nola Mike wrote:
> you most likely won't be as fast

Actually, it's rather the opposite -- lower octane (with no pinging) will give you more power, and hence, better MPG.

That doesn't seem to be quite accurate.

"It is important to note that the theoretical energy content of gasoline
when burned in air is only related to the hydrogen and carbon contents.
The energy is released when the hydrogen and carbon are oxidised (burnt),
to form water and carbon dioxide. Octane rating is not fundamentally
related to the energy content, and the actual hydrocarbon and oxygenate
components used in the gasoline will determine both the energy release and
the antiknock rating."

In short, octane rating defines how fast the gas burns, and how resistant it is to pre-ignition. It does not define how much energy content the gas has, so lower octane gas can't make more power. It doesn't have any more energy to offer than higher octane gas, it can just be burned in a less-demanding environment. Running a turbo or a high compression ratio? Then you need a better-behaved fuel (a higher octane rating). Same energy content, but better manners.

[Peer]

JackG wrote:
> That doesn't seem to be quite accurate.

I'm sorry if I rain on anyone's parade -- but the lower the octane you can get away with (without pinging), the more power.

-- peer

[JackG]

Originally Posted by Peer

JackG wrote:
> That doesn't seem to be quite accurate.

I'm sorry if I rain on anyone's parade -- but the lower the octane you can get away with (without pinging), the more power.

-- peer

No rain here... the science just doesn't back you up on this. It seems you have a misconception on what "volatile" means. It is not a measurement of energy content.

You wrote "87 octane has more potential horsepower than 93 (or higher) octane." "The lower the octane number the more volatile the gasoline -- by comparison, the higher the octane number the less volatile (combustible) the gasoline."

You are asserting that the more volatile gas is, the more horsepower it can produce. That's simply incorrect. They have different burn characteristics, but the same amount of energy. Energy produces horsepower, not volatility.