91 octane vs racing gas (pros and cons) - Racing Forum

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91 octane vs racing gas (pros and cons)
Monday, July 25, 2011 7:39 PM
I am looking for someone's experience or different opinions about running race gas on a stock circle track car. We have 2 cars we run at different tracks and was wondering if there would be an advantage to running race gas on a basically stock motor even though it is turning high rpms over normal 91 octane pump gas. We have a 93 2.2 5 spd with a CIA and Hedder and the other car is a 97 2.2 5spd both stock engines. Both cars are competetive currently but would the race gas give us more bang for our buck or would it be a waste. Thanks for your opinions.

Re: 91 octane vs racing gas (pros and cons)
Monday, July 25, 2011 8:18 PM
Without tuning it is not going to help.



FU Tuning



Re: 91 octane vs racing gas (pros and cons)
Tuesday, July 26, 2011 3:35 AM
I could be wrong but I was under the impression that race fuel won't help you out unless you need it (ie 91 octane isn't enough for the power your running). I know the guy that tuned my car runs his 2.2 acura on 91 octane and has no problem with his 450whp. Mind you he runs a tune for race fuel that he is able to push out 600whp.



Re: 91 octane vs racing gas (pros and cons)
Tuesday, July 26, 2011 3:30 PM
That was my thoughts that without a tune the 91 octane would be sufficient. Thanks..
Re: 91 octane vs racing gas (pros and cons)
Monday, August 01, 2011 12:24 PM
I mean you could weld some extra material into the combustion chambers to add some compression and then need race gas to prevent detonation and get some extra ponies.... But that would be against the rules...


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Re: 91 octane vs racing gas (pros and cons)
Friday, August 12, 2011 8:53 PM
I ran 108 race gas and 91 pump gas 50/50 in my 91 2.3 lo the car was .2 a lap faster on a 3/8 mile paved track
Re: 91 octane vs racing gas (pros and cons)
Sunday, August 14, 2011 8:14 AM
Mike Golding wrote:

I ran 108 race gas and 91 pump gas 50/50 in my 91 2.3 lo the car was .2 a lap faster on a 3/8 mile paved track









Re: 91 octane vs racing gas (pros and cons)
Sunday, August 14, 2011 5:25 PM
Mike Golding wrote:

I ran 108 race gas and 91 pump gas 50/50 in my 91 2.3 lo the car was .2 a lap faster on a 3/8 mile paved track


lol

that .2 seconds can attributed to anything.



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Re: 91 octane vs racing gas (pros and cons)
Wednesday, August 24, 2011 9:52 AM
we kept good records on everything we do to the cars and only make one change at a time buffed tires are good for .3 and soaking tires another .2 and longer tire life
Re: 91 octane vs racing gas (pros and cons)
Wednesday, August 24, 2011 10:10 AM
The point is, if the breeze was blowing a different direction it could make up .2. if you take a turn 1mph faster it could make up the difference.... race gas is a waste unless you are really tuned for it, and REALLY needing it.



Re: 91 octane vs racing gas (pros and cons)
Tuesday, September 06, 2011 5:08 PM
We run 90 octane non-ethanol in most of the 4 cylinder cars at our track and they all seem to work better with it than the 93 octane ethanol gas they had before...

Re: 91 octane vs racing gas (pros and cons)
Wednesday, September 07, 2011 2:48 AM
Octane rating is a measure of how slowly the particular grade of fuel burns, and thus, how resistant it is to detonation or pre-ignition. If you're not seeing any knock or timing retard with 91, race gas isn't going to do anything for you. Hell, even 91 vs 87 more likely than not isn't going to help you on a stock motor.




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Re: 91 octane vs racing gas (pros and cons)
Saturday, December 03, 2011 1:44 AM
JerseyJayLN2 (Scarab) wrote:

Octane rating is a measure of how slowly the particular grade of fuel burns, and thus, how resistant it is to detonation or pre-ignition. If you're not seeing any knock or timing retard with 91, race gas isn't going to do anything for you. Hell, even 91 vs 87 more likely than not isn't going to help you on a stock motor.


Exactly, I think some people have the misconception that higher octane causes a bigger explosion in the chambers, since it is rated higher that it is somehow more powerful, when in reality it basically is just harder to ignite to prevent detonation, so lower octane is faster burning and can ignite before TDC, detonation, while higher octane would be more stable in the same situation. Usually only high compression or boosted engines see a benefit and that is just to keep you from having detonation.
Re: 91 octane vs racing gas (pros and cons)
Sunday, December 25, 2011 5:15 PM
Bob Johnson wrote:

JerseyJayLN2 (Scarab) wrote:

Octane rating is a measure of how slowly the particular grade of fuel burns, and thus, how resistant it is to detonation or pre-ignition. If you're not seeing any knock or timing retard with 91, race gas isn't going to do anything for you. Hell, even 91 vs 87 more likely than not isn't going to help you on a stock motor.


Exactly, I think some people have the misconception that higher octane causes a bigger explosion in the chambers, since it is rated higher that it is somehow more powerful, when in reality it basically is just harder to ignite to prevent detonation, so lower octane is faster burning and can ignite before TDC, detonation, while higher octane would be more stable in the same situation. Usually only high compression or boosted engines see a benefit and that is just to keep you from having detonation.



Yes, gasoline is pretty much gasoline in how fast it burns. The desired effect of increased octane is to enable the fuel-air mixture the ability to absorb more heat before self ignition, aka detonation happens.

Interesting fun fact; I think it was Honda, way back in the 60's, who built a 50cc, 4 cylinder, 4 valve per cylinder motorcycle. IIRC they found that they could make more power by running lower octane fuel, not because it contained more energy but because it could be fired soon enough to completely burn the fuel. This was because of the high rpm it was turning, roughly 20k. I think it made about 20hp.

thanks,
dennis
Re: 91 octane vs racing gas (pros and cons)
Thursday, January 26, 2012 6:01 PM
Bob Johnson wrote:

JerseyJayLN2 (Scarab) wrote:

Octane rating is a measure of how slowly the particular grade of fuel burns, and thus, how resistant it is to detonation or pre-ignition. If you're not seeing any knock or timing retard with 91, race gas isn't going to do anything for you. Hell, even 91 vs 87 more likely than not isn't going to help you on a stock motor.


Exactly, I think some people have the misconception that higher octane causes a bigger explosion in the chambers, since it is rated higher that it is somehow more powerful, when in reality it basically is just harder to ignite to prevent detonation, so lower octane is faster burning and can ignite before TDC, detonation, while higher octane would be more stable in the same situation. Usually only high compression or boosted engines see a benefit and that is just to keep you from having detonation.


not disagreeing with you here but just wanted to point out the spark is fired prior to TDC, Spark advance is degrees before TDC. detonation is ignition prior to spark. But yeah lots of misinformation and incorrect assumptions about higher octane fuel.

also, OP, i would imagine you wouldn't run a cat but some race gas can be leaded and this plugs the cat. but prob a non-issue.



Re: 91 octane vs racing gas (pros and cons)
Thursday, September 27, 2012 9:23 PM
94 octane + 15* timing (safe street setup / 12 lbs boost) = 113mph trap speed

94 + 113 leaded + 19* timing + 115 mph trap speed (but a lot more traction issues)

Race gas will only help you if you can tune for it, if your not knocking with 87/91 octane, I wouldn't bother until you really start modding.



Re: 91 octane vs racing gas (pros and cons)
Thursday, September 27, 2012 9:24 PM
Isaak wrote:

94 octane + 15* timing (safe street setup / 12 lbs boost) = 113mph trap speed

94 + 113 leaded + 19* timing = 115 mph trap speed (but a lot more traction issues)

Race gas will only help you if you can tune for it, if your not knocking with 87/91 octane, I wouldn't bother until you really start modding.




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