I was wondering if it is bad to be running my car on a 93 octane preloaded tune from SCT while I have 87 in the tank? I had put it on before the weekend thinking I was going to the drag strip but it got rained out. I was too lazy to load it back to stock and I ran it today with regular fuel and it really didn't run that bad.

That thought just crossed my mind and it's not like I'm going to be running my car on the 93 octane tune, I will eventually change it back.

 

Generally, it's not a good idea to run the 93 octane tune on 87 octane gas. Your car will start having some detonation, especially if you give it any large amount of throttle. You can drive it on the 87 octane gas if you drive conservatively, but I personally wouldn't do it.

 

I will just take it off tomorrow then, no sence in risking it. It was more of a 'what if' question.

 

Like switch said, it's bad. The timing is advanced pretty far on 91/93 tunes and you can ping your way to a new piston without even knowing you're doing it. If you plan to race with the hot tune on it, then run your tank nearly empty of 87 and fill it with 93. Even 10% 87 octane in the tank is enough to drop the total effective octane down by a point or 2 and you don't need to risk it.

 

Agreed.

I put the stock tune back on this morning.

 

I remember when SUNOCO gas stations had 94 Octane..now they go up to 93 only

 

Half of the gas stations here have 93 and the rest 92. I have to keep my eye out if I even want to find a good deal on 93, but it's not that bad.