85 octane
While traveling out west this summer I noticed most of the gas stations offering 85 octane and 87 octane as their mid grade. Has anyone tried this in their gasser? I wasn't going to try it especially ...
Forum Discussion
Hi,
I'm reasoning that, as has been said, at the higher elevations, the atmospheric pressure is less, thus less air is being drawn into the cylinders on a normally aspirated engine. Since there is less fuel/air charge in the cylinder, pre-ignition becomes less of an issue (similar to having a lower compression ratio), so a lower octane (octane is added to help limit pre-ignition) fuel can be used.
That is why normally aspirated engines produce less power at higher altitudes. Slap on a turbo-charger or super-charger and this effect is minimized greatly.
I'm sure there are more technical explanations, but I believe that is it in laymans terms.
~Rick
I'm reasoning that, as has been said, at the higher elevations, the atmospheric pressure is less, thus less air is being drawn into the cylinders on a normally aspirated engine. Since there is less fuel/air charge in the cylinder, pre-ignition becomes less of an issue (similar to having a lower compression ratio), so a lower octane (octane is added to help limit pre-ignition) fuel can be used.
That is why normally aspirated engines produce less power at higher altitudes. Slap on a turbo-charger or super-charger and this effect is minimized greatly.
I'm sure there are more technical explanations, but I believe that is it in laymans terms.
~Rick
