8 replies to this topic

[SakoTGrimes]

Well, don't have a Subaru any more but I found out there's a gas station in town that sells race gas. I didn't look but I'd bet it's 100+ octane and $6+ a gallon. Would it hurt to run a few gallons through an EA engine?

[leon]

Im sure this point will cause alot of controversy. but i would recommend against it, from what i have read about octane ratings about petrol.
these older engines were not made to run such a fuel and as such it might just cause some damage in the long run.
plus its too expensive

[GeneralDisorder]

Octane is a rateing of the resistance of a fuel to spontaneous detonation - nothing more. 100+ octane on it's own means little other than it can be compressed much more before detonation will occur. With higher octane comes a lowering of BTU's per gallon - the measure of potential energy the fuel contains. For best performance and econemy you should always run the LOWEST octane your engine will stand without detonation. "Race" gas probably contains some very corrosive octane boosting agents that would not contribute to the longevity of your engine. Racing engines are just that - for racing. They are not designed for long life or reliability over a time period. They are designed usually to run at high RPM for sometimes as little as 1 or 2 races before being replaced or rebuilt. This allows the use of corrosive octane boosting agents, as well as the use of oxidizing fuels like NOS.

So no - don't run it in a soob engine - unless you built it with 10:1 compression just for racing. Your mileage would decrease, and your power would decrease with 100+ octane in a normal engine.

GD

[Loyale 2.7 Turbo]

...So no - don't run it in a soob engine - unless you built it with 10:1 compression just for racing. Your mileage would decrease, and your power would decrease with 100+ octane in a normal engine.

GD

I Agree Completely... Don`t use it.

[Caboobaroo]

Octane is a rateing of the resistance of a fuel to spontaneous detonation - nothing more. 100+ octane on it's own means little other than it can be compressed much more before detonation will occur. With higher octane comes a lowering of BTU's per gallon - the measure of potential energy the fuel contains. For best performance and econemy you should always run the LOWEST octane your engine will stand without detonation. "Race" gas probably contains some very corrosive octane boosting agents that would not contribute to the longevity of your engine. Racing engines are just that - for racing. They are not designed for long life or reliability over a time period. They are designed usually to run at high RPM for sometimes as little as 1 or 2 races before being replaced or rebuilt. This allows the use of corrosive octane boosting agents, as well as the use of oxidizing fuels like NOS.

So no - don't run it in a soob engine - unless you built it with 10:1 compression just for racing. Your mileage would decrease, and your power would decrease with 100+ octane in a normal engine.

GD

so then why is Japans lowest octane rating as good as our premium rating and they still run it in these motors for the most part? Their premium is like 120 octane or so. My friend who used to live there, just went back and visited a couple weeks ago and he was telling me about it. Also, their fuel is pink, instead of a brownish tan crap color like ours is. Now I know when I move back to Washington, I'm going to have to run premium and then some maybe in my RX...

[daveyandhisboost]

I was under this impression that octane only resisted detonation.... As far as agents in the gas, i would agree that they're is probably additive's in it. BUT; I thought the controversy was over Melting cats b/c of what comes out of the burn cycle. The risk of clogging your exhaust pipe via heat melt is higher. I dunno just food for thought.

[GeneralDisorder]

so then why is Japans lowest octane rating as good as our premium rating and they still run it in these motors for the most part? Their premium is like 120 octane or so. My friend who used to live there, just went back and visited a couple weeks ago and he was telling me about it. Also, their fuel is pink, instead of a brownish tan crap color like ours is. Now I know when I move back to Washington, I'm going to have to run premium and then some maybe in my RX...

There's probably a crapload of ethanol in it too....

And you are forgetting that in the US octane is calculated differently than the rest of the world.

GD

[jacobs]

If you want high octane, run CNG (compressed natural gas). As I recall, it has an octane rating of about 125 but don't expect good gas milage or an increase in performance. In fact you'll experience a decrease in performance unless you're running at least a 14:1 compression ratio. At least it doesn't have any additives.

This is my own personal experience after installing CNG on about 50 vehicles about 15 years ago.

[SuBrat84]

I ran a tank of 100 Octane from 76 (BP Racing Fuels) in my SVX. It ran a little smoother, more quiet, and a little cooler (noticable on the temp gauge) I didn't notice any effect on my gas mileage or performance however. It was not worth the $5.50 per gallon that it cost (in December) but also I wasn't paying for it.

Edit: The noise my exhaust makes is now any thing below 2k rpms instead of up around 4k rpms... may or may not be related to the gasoline. More likely related to my driving habits.