[VaSteve]

Is there a recommended octane booster? I filled up with some 87 in a moment of weakness (and reading the manual). Ran OK, until I got on it after the motor was well warmed up last Friday when it was ~80 degrees. It did not sound good (kinda like the old roller coaster up the hill - I guess that's pinging). Anyhow internet "wisdom" said to put in some octane booster and fill the tank with the good stuff like I should have. Internet "wisdom" also claims that octane booster is a load of crap.

So anyone here know? Yeah/nea?

[Trak Ratt]

Real wisdom is to drain 3/4 and use in lawnmower.

[rs911t]

Originally Posted by VaSteve

Internet "wisdom" also claims that octane booster is a load of crap.

In this case believe what you read on the Internet.

Originally Posted by david riley

Real wisdom is to drain 3/4 and use in lawnmower.

Also, mix in a little race gas. It'll smell like you're at the track when mowing the lawn.

[cmartin]

I would just fill it up w/ 93 and drive a little easy to burn off a few gal, then fill it up again.

[racer]

Originally Posted by VaSteve

Is there a recommended octane booster? I filled up with some 87 in a moment of weakness (and reading the manual). Ran OK, until I got on it after the motor was well warmed up last Friday when it was ~80 degrees. It did not sound good (kinda like the old roller coaster up the hill - I guess that's pinging). Anyhow internet "wisdom" said to put in some octane booster and fill the tank with the good stuff like I should have. Internet "wisdom" also claims that octane booster is a load of crap.

So anyone here know? Yeah/nea?

87 in the 911 is not so good.... Perhaps if your car was a DME contorlled Carerra it would have backed down the timing and a knock sensor would intervene... Since yours is CIS, well, forget that...

A few choices:

1) Do nothing and hope for the best (drive under light throttle)
2) Drain tank completely and refill
3) Drain tank down to about 1/2 level and fill up with 93-94 and then add more 93-94 after 1/4-1/2 tank of consumption
4) Try some octane booster.. it can't hurt any more than running the wrong octane to begin with
5) Ask another Dorki to kick your ass if you ever try to save $2.00 over the cost of a tank of gas to use 87 instead of 91-94!

[Noah]

The early SC's ('78-'79) do fine on 87 with their 8.5:1 compression, assuming there isn't a massive amount of carbon caked on the tops of the pistons. The later SC's with 9.3:1 need higher octane gas. Bad Steve! Bad Steve!

Probably the most straightforward solution is going to be to drop the engine, tear down the motor and install 8.5:1 compression pistons until you go through that tank of gas, and then do it over again to reinstall the 9.3:1 pistons. We're here to help.

[Trak Ratt]

Originally Posted by racer

Ask another Dorki to kick your ass if you ever try to same $2.00 over the cost of a tank of gas to use 87 instead of 91-94!

I'm here for you Steve if needed

[racer]

Originally Posted by Noah

The early SC's ('78-'79) do fine on 87 with their 8.5:1 compression, assuming there isn't a massive amount of carbon caked on the tops of the pistons. The later SC's with 9.3:1 need higher octane gas. Bad Steve! Bad Steve!

Probably the most straightforward solution is going to be to drop the engine, tear down the motor and install 8.5:1 compression pistons until you go through that tank of gas, and then do it over again to reinstall the 9.3:1 pistons. We're here to help.

Steve's signature says his SC is an '83 ... I smell engine drop

[VaSteve]

LOL. Thanks guys. I wasn't quite sold on the idea so I never committed to a full tank. It was a fellow Dorki who recommended that I check the manual (and I did) it does call for 87 (US pumps). Believe it or not.

Then again, I forgot to factor in for disabling the O2 sensor and fooling with the mix. Bad me.

I think I will follow Dave's method of fill, refill, refill I want to burn all this out before the AX this weekend. A couple of drives to work at the usual speed, I should have no problem burning off the rest of the tank.

[RoninLB]

fwiw.. I've been slowly testing lower octane gas this winter. So far I'm ok with 87 that's blended with 10% alc. The idea was to stretch miles on a tank, not to save money. I didn't want to experiment in the summer due to ambient heat. I've been running a few tanks of 87 and so far no pinging. I've now the confidence for the warmer weather. Mileage is increasing.

I'm not suggesting anyone else try this as the pinging sound reaching your ear is not a good indicator. I'm very set up with engine monitoring so I'll know instantly the results. Pinging is detonation and detonation is a c hair away from pre ignition. Pre-ignition blow engines.

Straight gas is diluted with additives to achieve octane. The less additives the more gas available/gal. The less additives the cleaner the combustion chamber and the cleaner the oil.

hope this helps.