What Gasoline to Use?

[n20junkie]

a little gasoline chemestry for those that might not be in the know, as far as performance goes, you always use the lowest octane rating needed to control detonation, the higher the octane rating, the less susceptable the gas is to uncontrolled explosive combustion, gas in a IC engine is supposed to burn, not explode, octane is used to control the burn, but in doing so its rate of burn is slowed, so if you run a higher than needed octane rating than all you get is a theoretically speaking slower car, becasue the flame is burning slower than optimal, if 97 octane burned faster than 87, than you would notice the performance advantage when you switch any car to the higher octane rating, but you don't, all you get is the higher resistance to detonation, and if detionation wasn't a problem before, than you won't notice a thing,. but our cars being turbocharged the the control of turbo boost and other varibles being less than perfect ( old wategates, injectors, ........) its best to run the highest octane you can afford within reason, if your car is stock or slightly modded, the 98 octane stuff will work, but if your car seems track time then most will advise bumping up to the race gas, but the lead will eventully hurt o2 sensors and converters, but will save a headgasket, all of this is of course is ignoring those with water/alcohol injection, which f course is used to deter detionation, again by controlling the rate of burn and keeping it from exploding, proof again that octane doesn't cause gas to burn faster, cause last time i checked water doesn't burn too well,
Grant

 

[kshef]

as far as performance goes?
when i use 100+ octane the car is an animal(stock park avenue)...get so much more timing

 

[bruce]

Originally posted by n20junkie
a little gasoline chemestry for those that might not be in the know, as far as performance goes, you always use the lowest octane rating needed to control detonation,

If, your just looking at immediate results, yes.

However, I did some fleet long term testing (years ago). The fleets were a small Police Dept., two tow truck firms, an ambulance service, and some sales reps..

For 100,000 miles, it always payed to run premium. The difference in additive packages were enough to recover the lose from premature valve jobs, and there was overall less *coking* of the ports, and runners. Often exhaust valve seat, and valve piting is from carbon flakes interupting the contact area, valve seat area, and this is the hottest point in the engine.

No there were no test controls, and no animals were hurt in this, just observations from watching an overall trend, and dealing with accountants.

I run the highest octane possible, from as busy as station as I can find. Texaco, Sunoco, BP, seem to be the best *standards*.

I also always carry an open loop chip for the ocassional tank of junk fuel, in the *truck* since the GN usually runs in open loop anyway.

 

[Blown&Injected]

As mentioned, all the gas in one area is coming from the same pipeline. The only difference is the additive that gets pumped in as the truck fills up. Even the no-name el cheapo is getting the same 87/89/93/94 as the Amoco or what ever down the street. Difference again is that El Cheapo gets a generic additive - how much difference is there in the additive package???

It seems the biggest difference would be who has the newest and cleanest tanks AND trucks to deliver too. Any station has got to do some serious volume to stay in business.

Sunoco (Sun Oil) makes Cam 2, and I believe Turbo Blue.

According to Sun Oil, race gas does not burn slower, and there are indeed some high octane race fuels that are designed to burn very fast. It seems Sunoco makes at least one for very high RPM engines.