Fuel?

[red_dog007]

Well, I know that this engine runs on 87 octane. Would there be any advantage if I put in 89 or 93 octane? I am just wondering if the engine prefers to drink a higher octane fuel compared to 87 octane.

[beandip]

Depends on the compression ratio of your engine . What the higher octane fuel is, is that it will NOT ignite at a lower compression. So if you have increased the compression of your engine , then it may require the higher rated fuel. I witnessed a dyno test where a Z actually made more HP with lower octane gas. The lower compression was not burning all the fuel . The early Zs were high compression engines and suffer predetonation or ''pinging'' with low test gas. I am running 9.5 to 1 and usually use plus fuel . This is not really a high compression ratio , especially since I am running a moderate cam , which requires a higher compression . I haven't dyno tested my car with different fuel however , I am not having any predetonation . I could most likely run regular grade gas . Your timing also comes into the mix here as well , more advance BTDC will also require a higher grade fuel. You could vary likely make less power with 100 octane gas in your stock engine . Gary

[MikeW]

As Gary said, Octane is the measure of the resistance to detonation. In other words, the higher the octane the harder it is to ignite. It's not somehow a measure of power but I think that people somehow associate the two since high-performance engines tend to be high-compression engines and therefore require higher octane. What you don't want to happen is pre-detonation or pinging. This is when the fuel/air mixture ignites before the spark. That's bad. If it's not pinging on 87 then higher octane buys you nothing (except for the fact that premium fuels might have better additives).

[sakijo]

The gas man told me that the octane rating was the MINIMUM. i.e. 87 octane may be 88,89,90 you don't know, but it was at least 87. As Gary and Mike said, as long as it doesn't ping, you're ok.