Another Octane question...
Thread Starter
Racer
Joined: Dec 2005
Posts: 399
Likes: 0
From: Kearns UT
Another Octane question...
Here in Utah we only have 85, 87 and 91 octane gasoline. I understand that most STOCK Corvettes will run fine on these octane ratings, but GM recommends that I use 92-93 in my ZZ502.
My question is.... What octane booster can I buy to bump my octane to 92-93 or is 91 ok? My engine is not pinging, but will the 92-93 get a few more ponies out of the motor?
SLC, UT is 4500 feet above sea level if this helps with anything.
I've heard from several people that the LUCAS stuff is the only stuff that really works. THOUGHTS?????
My question is.... What octane booster can I buy to bump my octane to 92-93 or is 91 ok? My engine is not pinging, but will the 92-93 get a few more ponies out of the motor?
SLC, UT is 4500 feet above sea level if this helps with anything.
I've heard from several people that the LUCAS stuff is the only stuff that really works. THOUGHTS?????
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Burning Brakes
Joined: Dec 2003
Posts: 1,004
Likes: 7
From: Adelaide South Australia
If you're sure that the motor isn't pinging with 87 octane, I'd stick with the setup you have now as that is readily available to you.
There is a bit of a performance gain with higher octane gas but only if you have tuned for it.
But if you do that, you will have pinging on lower octane gas.
There is a bit of a performance gain with higher octane gas but only if you have tuned for it.
But if you do that, you will have pinging on lower octane gas.
Racer
Joined: Jun 2006
Posts: 476
Likes: 0
From: Easton PA
go to the paint shop and get a bottle of 'toulene' , its 114 octane out of the can. it is almost a solvent i think. many people use it because its cheap no fuel tax on it. it is harmelss to the car as well.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Gotta disagree here. Your statement would only apply if the motor had previously been de-tuned to avoid pinging, usually meaning that the timing would be less advanced than optimal.
The OP's motor is already set up for optimum performance, ie. no compromises were needed to run it on 91 octane.
It is false to state that there is an endless loop of increasing octane, which allows more advance, which means more power. Once you've hit optimum advance (usually 36 degrees) then any additional will DECREASE output, not increase.
Pro
Joined: Apr 2007
Posts: 736
Likes: 1
From: Chester VA
Detonation begins to be harmful before you can hear it or feel it. Octane additives are junk, they don't really bump octane as much as claimed. I'd mix 91 with race gas if I were you. I can tell a noticable difference in my 10.5 iron headed small block between 93 and 100, even without a retune, even with no detectable pinging with 93.
Burning Brakes
Joined: Dec 2003
Posts: 1,004
Likes: 7
From: Adelaide South Australia
Gotta disagree here. Your statement would only apply if the motor had previously been de-tuned to avoid pinging, usually meaning that the timing would be less advanced than optimal.
The OP's motor is already set up for optimum performance, ie. no compromises were needed to run it on 91 octane.
The OP's motor is already set up for optimum performance, ie. no compromises were needed to run it on 91 octane.
I would say his tune is NOT optimised for best power with 92~93 octane.
He states the motor runs OK on 87 with no detonation, and that indicates to me he has left some horsepower on the bench.
(A GOOD idea in his situation)
All I was intimating was he should tune his motor so that it runs safely with the readily available gas in Utah, which is 87~91.
He states that GM recommends 92~93 octane for the ZZ502.
I would say that recomendation is so that the motor will meet it's advertised power specs.
The ZZ502 will run OK on 87 if the timing and fuel curve are setup for it, but power will be lower than if the motor IS tuned for optimum performance using a higher octane fuel : eg 92, 93 or 100 octane.
I might just add for our original posters benefit.... Use 91 octane fuel if it is readily available.
The difference between that and an increase to 92 or 93 would be minimal anyway.
Last edited by OzzyTom; Apr 15, 2008 at 09:52 PM.
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Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Ah, no he didn't. He's able to obtain 91 octane and by inference we can assume he's using it rather than buying 87 and trying to boost it.
So, assuming that he's using 91 and has no detonation and has not fiddled with the timing to achieve this, he will gain nothing by increasing octane to a higher rating.
And once again-It is false to state that there is an endless loop of increasing octane, which allows more advance, which means more power. Once you've hit optimum advance (usually 36 degrees) then any additional will DECREASE output, not increase.
But you can beleive what you want.
So, assuming that he's using 91 and has no detonation and has not fiddled with the timing to achieve this, he will gain nothing by increasing octane to a higher rating.
And once again-It is false to state that there is an endless loop of increasing octane, which allows more advance, which means more power. Once you've hit optimum advance (usually 36 degrees) then any additional will DECREASE output, not increase.
But you can beleive what you want.
Drifting
Joined: Nov 2002
Posts: 1,674
Likes: 197
From: Loveland, CO
The oil companies know you can get by with less octane at altitude than you need at sea level. That is why you won't find 93 at any regular gas station over probably 4000'. Higher altitude means less dense air which means less compression ratio which means less octane requirement. All owner's manuals refer to octane at, or near, sea level.
Ralph
Ralph
Last edited by rponfick; Apr 15, 2008 at 10:25 PM.
Burning Brakes
Joined: Dec 2003
Posts: 1,004
Likes: 7
From: Adelaide South Australia
