What octane of fuel does everybody run in there car? I have a 89 small block 350 with some mods and was wondering what would happen if I ran 87 in it.

 

it depends on your compression, and timing. if you have a moderate tune on it and lower compression you can run 87 just fine. otherwise you will knock.

 

A couple days ago I filled up with 87 and the check engine light comes on sometimes the car knocks and drives like crap. I added some 93 and octane booster and back to normal.

 

if the car knocks then i would assume you have too much compression or timing to run lower octanes. better stick with the good stuff

 

I think I put 87 octane in once and then read the owner's manual. 91 octane ever since, 'cept when I'm at an Esso station 'cause they have 92 there.

If 87 causes problems, step it up, if it still causes problems, go up again, right? Remember it takes more than one tank of gas to get it to the "true" octane value.

 

some 20 years ago I was dating a girl that had a ford t bird that just constantly knocked. one day just for the heck of it I went up just one grade. in less then a minute after starting itup(carbed), the knocking was totally gone and the MPGs went up by about 2. but backthen, gas was someting like an expensive 78 cent a gallon.lol. so I would agree with them and just keep going better till it stops and possibly going one more just to be safe, but that last part would be a personnal preference on your part.

 

Try the midgrade. With to high an octane you run the chance of not a complete burn.

 

with the energy of gas combustion, and the fact that the heat of the chamber alone can ignite it, you would have to be running 300 rating gasoline before that is an issue. if you arent getting full combustion of gasoline you will want to look toward your air/fuel mixing well before you look at octane. for al intents and purposes you can never go too high with octane, but there is a point where u are wasting money because you eliminated all knock 3 points ago

 

Did anybody even consider that maybe his knock sensor or wiring may be bad?
With a proper operating knock sensor controlled ignition, you shouldn't even be hearing an octane knock.
If you do, then there are more serious issues to deal with, other than the octane rating of the gas.

 

i dont know the capabilities of the 89, otherwise i would have considered that. and knock gets misinterpreted so often when people hear "knock" i usually dont get too concerned. could potentially be any number of sounds from a struggling motor. ive never driven a classic muscle car so i actually have no idea what knock (or ping) sounds like. i just know how to identify it in a tuner