VonK :: Retired

Who knows the difference in heat content (BTU/gal) between 87 and 93 octane pump gas? TIA

WJM

The difference in heat content isnt as much of a player in internal combustion dynamics, as its flame speed, pre-detonation characteristics, and the car's ignition timing

VonK :: Retired

I'm looking for numbers.

JAFO

little or none. octane rating is not a measure of energy content or burning temp.

VonK :: Retired

As I said before, I'm looking for numbers.

JAFO

btu may vary with refinery and base stock. as well as other factors such as volatility.<ul><li><a href="http://www.vermontfuel.com/server/energy_specs.html">http://www.vermontfuel.com/server/energy_specs.html</a</li></ul>

VonK :: Retired

So, all else being equal at the same pump, there's almost 10% more energy in a gallon of 98 octane gasoline vs. 87. Possibly, the extra aromatics added to get to 98 octane contribute to that? They seem to be both denser and of equivalent heat of combustion. This, beyond improved timing and other consequences should lead to better mileage with the same driving style.

I have a new Toyota Highlander Hybrid, for which the manual claims better performance with premium gas. I also have a can of 100 octane fuel left over from my stage 3 S4. Do you think I'll notice a but dyno difference? We'll see.

JAFO

beyond what the car needed to run right. my jetta got the same performance and milage on 89 and 93. but on 93 it smelled of SO2.

VonK :: Retired

Better SO2 than HS2. Did you have a new cat?

JAFO

could have been that too. no new cat and this happened several times.