Which do you guys like better? 93 or 94 octane? I recently started using 94, and my car seems to run better, but I don't know if I just "Think" It runs better. What do you guys think?

 

I haven't noticed any knocking as of yet... even on the hot, humid days. So I keep running 93 instead of paying the extra $$$ for 94 octane. That's just for now, though since I'm still breaking in my engine. :-)

 

More octane will actually hurt you if your car doesnt actually need it.

If you have no knock with 93, your wasting your time with 94.

At ramchargers where i would i have had people tell me their cars run seconds faster at the track with race gas.. yet they have no proof..

 

Using higher octane gas than necessary/recommended is a waste of money. The octane required by your car is dependent on the compression ratio - nothing else - due to the temperature of the compressed air, and the temperature that the different grades of gasoline burn at. LS1's call for 91, although the book even says that 87 is "acceptable", so for now, I've been running 87 on a regular basis, and run a tank of 91 occasionally (when I can afford to, since I've just started a new job, and I'm adjusting to the hefty car payments).

By running 87 octane, it actually burns easier than 91 octane (or higher), although when 91 burns, it will burn hotter, but to run higher octane gas, you need a higher compression ratio to generate the heat to completely burn the fuel, otherwise it'll actually not burn as "clean" or "efficiently".

Besides, if the book recommends 91, with 87 being acceptable, why would you bother running higher??? Higher octane "superclean" fuels I'm sure are just a marketing gimmick to lure people into spending more money for no reason. For now, I'll stick to my 87 or "recommended" 91 octane. If the compression increases in my car someday, then I'll run 93/94. JMO.

 

My understanding is that 10:1 compression is close to the upper limit of 93 octane gasoline. I would NEVER run anything lower than 93 unless it was an emergency situation.

Perfect example ... my 2001 Z28 was a demo car and the manager's wife ran 87 octane for the first 3,000 miles. I had to have the GM Top End cleaner procedure done THREE TIMES to remove all the carbon and crap. DON'T RUN 87 OCTANE

Since I can't get 94 octane here in Memphis, I run 93. I've had a little trouble with detonation on the WS6 and have removed the Hypertech tuning. I'm also running OEM MAF ends and the OEM screen. I still get a bit of detonation, so my next step is to add some Toluene to the gas and increase my octane a little more and see if it goes away.

So ... if your car runs good on 93 octane, with no detonation, then 94 or higher would just be a waste of money. In my case, when the weather is cool, 93 works just fine. But when it's hot and muggy, then I need a little more octane to keep detonation down.

 

Wife ran 87 octane?!? Ouch! Just goes to show that you should never let a woman drive a mans car!

 

Exactly, we only have 91 and 92 here. Even if you do get some KR, you can do some tuning to make it work.

 

93.. no choice here in Houston.. but thats ok..
works fine for all of my cars.

 

I can only get 91 octane also here in IA. how bad is this and other then carbon buildup, what else does this hurt? detonation occurs now and then but I was told I might need new spark plugs which I plan on getting done soon.....

 

Also remember that octane requirements change with elevation. A higher elevation won't need as much octane as a lower elevation.

 

A common rule for carbed cars is that you take the engines compression and multiply it by 10 to get the recommended octane to use. So a car with 9:1 compression would probably need around 91 octane. this is ofcourse give or take a few points due the engines individual tuning. Computer controlled fuel injected cars can usually bend these rules a lot more than the old school cars.

I'm assuming everyone knows this already, but for those who dont, octane is added to fuel to make it burn slower. The standard gas law (PV=nRT) tells you that as you compress a gas, it heats up. No one wants detonation in their

The best way to find out what gas is best for you engine is to test them out. Assuming that power isnt that great of a concern for daily driving, havign the highest octane gas isnt always best. It does afterall require more energy to burn than say 87 octane. See how your milage increases or decreases with each grade. If you get the same milage with 91 that you do with 93, why pay the extra $1.50 a tank? It doesnt seem like much, but it adds up over time.

And yes you can run 87, the computer will compensate for it by retarding the ignition. Sure you'll lose power, but it doesnt cause damage. Hondas for example wont activate VTEC unless there is high grade fuel in the tank. If I had one, I would probably run 87 all the time unless I knew I was going to be revving it up. It'd save money.

So yeah. do some testing and see if youre really gaining anything by spending the extra money.

 

been using 94 recently, don't really notice any change going back to 93 which was fine before.