Planet 9

Does anyone know if any gas stations in Atlanta (ideally Roswell/Alpharetta area) carry gas above 93 Octane at the pump?

Try this link:

Race Gas

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At what point does higher octane become a problem? Also, what about octane boost additives?

Can we use JP Fuel?

Greg,

The pumps at Road Atlanta have several grades of high octane unleaded race fuels. Come up to the club race at the end of March, and fill-er up. - long time no see!

I do know a guy with a C5 Z06 got some weird OBD warning when he went overboard and filled up completely with something like the 104 octane at a DE last year (at $6 or $7 bucks a gallon no less.....) I don't know if you would need to be concerned with that or not......

Regards,

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In2Esses

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If you get confirmed locations I will add them to the map.

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when its leaded I really dont see a need for anything above 100 in a naturally aspirated vehicle though. 100 octane should be enough for track events too. I ran 104 in a twin turbo vehicle and 19lbs boost and it was sufficient.
I've read reports stating addiditives can actually lower the octane rating. Dont waste your $$.

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I have spent a few years in the oil business and I can tell you that octane additives are a joke, total waste of money.

If by JP Fuel you mean jet fuel the answer is no. Jet fuel is kerosene, so the flash point is too low and the distillation range is wrong, among other things. Most small airports sell Avgas, which is generally over 100 octane, but with today's security issues you may not be able to get to the pumps.

If you haven't found any high octane gas go by Ferrari of Atlanta in Alpharetta and ask Harold in the parts department if he has any suggestions.

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You should not have a problem getting AVGAS at most small airports not served by commercial aircraft. They don't have the same security requirements.

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Cayman Club Outsider

Thanks. Ok AVGAS is what I was looking for. I thought the additive claims were a joke. Same as electric super chargers!

Higher octane won't be of any use, passed the point of the engines requirements. And unless modified that is 93 Octane.

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LL

Thanks everyone. Some of the other car boards report a couple of Sunoco stations carry 100 Octane. I might take a road trip to find out - if I find something I will post it. In terms of performance - I have never tried it and just want to see.

If I'm not mistaken, there are one or two gas stations on Hwy 53 near Road Atlanta that sell gas over 93 octane, and at prices much lower than the pumps at Road Atlanta proper. I didn't see them on the map which Nick posted a link to, and still not that close to Roswell.

Just to expand on what others are saying, you probably won't notice any performance difference by using higher octane in a stock engine. In general, higher octane fuel burns slower, so it helps prevent pre-ignition, aka pre-detonation, aka knock. If you are right at the edge of starting to knock a sensor will retard ignition, but you would also probably get a CEL. So, if there's no warning light you probably don't need more octane. More octane does not equate to more power.

OTOH race gas is higher quality fuel than mainstream pump gas, but is it worth the premium price?

Ok - I found a Shell station at the 372 (Crabapple) and Mayfield road. For those familiar with the area go north past the silos in Crabapple about a mile. They had 100 octane at one of the pumps. $9.99 a gallon!!!! I had about a quarter tank of 93 and bought five gallons of 100 so probably about 96 or 97 in the tank. I can't really tell any difference (I do have SRP and AWE exhaust) - well at least I tried it and know.

Shell,

There's a gas station up 400 somewhere north of 53. It's a Chevron and its on the right. We used to always stop there and gas up before our mountain runs. They have 104 I believe. It's a pump all by itself away from the main pumps.

Well, valuable experiment then. Many people think that a higher octane fuel will have a higher energy density than a lower octane similar fuel, more energy per gallon, or more energy for each stroke of the engine, but it really isn't the case.

The mods you mentioned allow your engine to get more air into, and out of the cylinders. You have a computer controlling the fuel/air mixture ratio, so since you allowed more air in with your mods, the computer adds more fuel to keep a correct ratio. You end up making more power by burning more fuel, works great, makes sense.

What your mods did not do was change the compression ratio of your motor, changing the maximum compression, another very efficient way to make more power. Higher maximum compression would require a higher octane fuel to run without knocking.

Running a fuel with too low an octane rating can result in less power, and can be harmful to an engine, but running a fuel with a higher octane rating than required doesn't really have any power benefits. It isn't that the lower octane fuel has less energy in it, it is your engine controls sensing knock and retarding the ignition to compensate.

I'll agree with everyone above that says you'll see little or no gain from gasoline with higher than 93 octane. However, I'll also let you know that if you did decide you need it (forced induction, etc), another great source is to buy toluene or xylene in gallons or five-gallon cans at specialty paint stores (like Sherwin Williams). You can add these straight to gasoline (these are some of the chemicals the fuel companies add to do the same) and improve the octane dramatically. Toluene is ~114 octane, so a gallon mixed with four gallons of 93 gasoline (20% ratio) will yield higher than 97 octane fuel that is perfectly safe to run in your car.