89 octane -- what's the point?

[Goat Blower]

A lot of my cars specify 91 octane or better, but I always run 87 octane, works just fine. If you can make use of better octane gas by running more boost and/or timing, then it's worth it.

100 octane gas will make an old carbureted Chevy run better because you can advance the ignition timing without pinging. I wouldn't waste the gas though in something like that unless I was running domed 12:1 pistons or higher. Or if it had a set of T88's on it.

[gofastman]

Originally Posted by Goat Blower

A lot of my cars specify 91 octane or better, but I always run 87 octane, works just fine. If you can make use of better octane gas by running more boost and/or timing, then it's worth it.

100 octane gas will make an old carbureted Chevy run better because you can advance the ignition timing without pinging. I wouldn't waste the gas though in something like that unless I was running domed 12:1 pistons or higher. Or if it had a set of T88's on it.

the only real practical use i can think of for 89 octane is a VERY heavily loaded truck going through a hot area using close to WOT for long periods of time, it may allow the PCM to run more timing than one with 87 under the same conditions

[xveganxcowboyx]

Originally Posted by Goat Blower

100 octane gas will make an old carbureted Chevy run better because you can advance the ignition timing without pinging. I wouldn't waste the gas though in something like that unless I was running domed 12:1 pistons or higher. Or if it had a set of T88's on it.

I asked him if he'd done anything to warrant the higher octane. He said no. "It just runs better, she likes it." Then he proceeded to talk about how my "japanese import" was a waste of time.