92 octane vs. 91 octane - Pontiac GTO Forum
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post #1 of 30 (permalink) Old 10-05-2004, 11:50 AM Thread Starter
 
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92 octane vs. 91 octane

Would there be any substantial difference in engine performance using 92 octane vs. 91 octane? I live in San Diego, CA. and have yet to see a pump that offers 92. 04 phantom black,m6,three weeks new with 1300 miles.
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post #2 of 30 (permalink) Old 10-05-2004, 12:25 PM
 
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Oh jeez! Didn't the dealer warn you about the 174.2 HP you'll be losing?

Well, as long as nobody imports 92 octane from Nevada, at least you'll be on the same relative standing as everyone else.

---Larry
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post #3 of 30 (permalink) Old 10-05-2004, 12:47 PM
 
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This may be a dumb question, but here goes...

Why do different states have varying octane ratings of their premium fuels? Is it a state law thing?

I live in upstate NY, and our high-grade gasoline is 93 octane, sith some Sunocos offering 94...
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post #4 of 30 (permalink) Old 10-05-2004, 03:27 PM
 
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You will never find 92 octane in California it is not available period, but if you could it would good to use it as the computer system on your car would be less likely to Knock retart your car resulting in better performance!

Robert
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post #5 of 30 (permalink) Old 10-05-2004, 03:32 PM
 
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Quote:
Originally Posted by yipching
Why do different states have varying octane ratings of their premium fuels? Is it a state law thing?

I live in upstate NY, and our high-grade gasoline is 93 octane, sith some Sunocos offering 94...
Because they can.

"Normal" Premium here is 93 octane as well, but a handfull of stations have "Racing" fuel that is 100 octane. It was $4/gallon when I last looked.

---Larry
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post #6 of 30 (permalink) Old 10-05-2004, 05:14 PM
 
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The higher the altitude the lower the octane. In Amarillo, Tx. where I'm at the highest you can buy is 90. I understand that in the mountains premium is 87. The closer to sea level the higher the octane allowed. Barometric pressure or something I don't understand. Explained to me by a gas distributer in the area when I went looking for 93.
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post #7 of 30 (permalink) Old 10-05-2004, 08:13 PM
 
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91 is the normal premium here in KC. Occassionally I find a BP station with 92. I drove fifteen miles down the freeway last Saturday to a Phillips 66 Truck Stop and put 10 gallons of 100 octane @ $3.99 per gallon. Just wanted to see what it did. I think it's a little faster but don't really know for sure. It doesn't start up as fast as with the 92 but it looks like it's getting a little better gas mileage and, needless to say, I have my foot to the floor as often as possible. I saw a review of gasolines on the web somewhere and they tested 87 using octane additives and then 102 (or somewhere in there) and there was a world of difference in the hp. The higher octane fuel gained 5 to 10 hp more than the 87 with the additive and they were able to manually advance the timing a lot further with the 102. The point was that the higher octane fuel was just an all around better gasoline.
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post #8 of 30 (permalink) Old 10-06-2004, 03:46 PM
 
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I think people are mis understanding what octane means to you! If you have a high compression engine higher octane is benificial to a certain point. In an old 60's high compression car with no computer management if you could not get the proper octain gas your car would knock or pre ignite the fuel in the cylinder before the spark plug ignited it very bad, but you could manually retard the timing advance to reduce or eliminate the problem! and also reduce performance, move forward to the gto it has an electronic system in place to compensate for lower than optimum octane and retards timing so your car runs without knocking but at a lower performance level. The trick is to buy the octane level that will allow your GTO to run with no knock retard thus obtaining maximum performance! IMO 91 octane in california is slightly to low to allow full performance the car runs but not to its true potential! on the other hand 100 octane is more than likley to much and does nothing more than 93/94 octane other than cost more! You are not being nice to your car by buying higher octane than your car requires! As the octane number increases all it means is that you can squeeze the air fuel mixture tighter before it pre ignites and damages the engine. years ago the oil companies used to only put the good additives into their premium gasolines! since the early 70' federal law has mandated these additives in all fuel grades.

Robert
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post #9 of 30 (permalink) Old 10-06-2004, 04:13 PM
 
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Thanks for the info. Even though I hadn't intended to fill up every week with 100 octane fuel, I won't do it again as I definitely don't want to hurt my engine. 92 octane is the best I can find here in KC so that will just have to do. As I had mentioned, I wasn't really sure I could tell any difference in the performance with the 100 octane anyway. With your explanation, I now know I more than likely wasn't. In the reference article I read about the octane additive, they kept advancing and retarding the timing when they changed the fuel so they were probably experimenting on an older muscle car without all the computers.
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post #10 of 30 (permalink) Old 10-06-2004, 05:08 PM
 
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So what will happen if you use 87 octane in the GTO?? Gas over here in Vegas is very expensive. $2.30 for premium. Does using 87 octane with additive good for the engine?
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