Octane Rating?
 

I always run 92 octane gas in my car until today. I was storming around town not noticing my gasoline gauge until I had about a gallon left. I hate running it that low but I had been in such a hurry to do all the things that I needed to do that it happened. I pulled into the first gas station that I saw. Hoped out of my car running to the cash register because I was already 5 minutes late to my moms dinner party. Came back and without noticing and I could have sworn up and down that I grabbed the 92 octane nozzle when in fact I grabbed the 87 octane which I didn't notice until I was done pumping. I was like oh shnap what have I done. No time for kicking my self in the *** so I hoped in my car expecting it run like crap until that gas tank went on empty. If you have read my older post of how I had problems after installing a set of heads that were ported and polished you can remember I mentioned that my car smelled rich no matter what I did and even when I thought I had fixed the problem it came back again. Well now with this gas it idles so much smoother doesn't smell rich and runs just about the same. I'm confused I thought higher octane was the key to making your street machine run better. Sorry for the long post it's just that I'm a little woried if it will come back and haunt me if I continue to use 87 octane.

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67'fastback-Edelbrock carb,intake,cam,valve springs.Rhode lifters, CompCam rocker arms, windage tray,cerama coated headers,dual flows with H-pipe, modded c-4,tci stall converter,perma cool electric fan,aluminum water pump,griffen aluminum radiator,accel 8.8 cable,wide cap distriburator,magnetic pick up,v-matic hurst shifter,edelbrock performer nitrous, carter electric fuel pump,ignitor coil,solid motor mounts,magna racing suspension,poly urathane bushings,under rider traction bars, comp. eng. s

I would not try to run that nitrous kit with the lower octane gas. I tried that in my car and it ran like crap with 87 octane, and it had a little detonation. You might try to back your timing back a little and run the 93 again.

Someone correct me if I am wrong but doesn’t the lower octane gas burn faster? So with a lower compression ratio motor I have been told that the lower octane gas works better.

I am confused, someone please explain this to me.

The octane rating only indicates how much compression the fuel can take before combusting without a spark. Higher octane fuels do take longer to burn, also. The higher the compression engine you have, the higher octane you should run. The same is true of advancing your timing. It's kind of a combination of the two.

If your car runs better and doesn't ping when under load with the 87, you may as well save some money and stick with it. Running too high of an octane fuel can actually lead to fouled plugs and carbon build up if your car isn't tuned correctly for it.

The other thing you might try is to advance your timing more for use with the higher octane. This will give the fuel more time to burn and may give you some more power in the process.


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351W 89 Mustang GT Convertible

If you don't have bumped timing or raised compression, there's no need for anything higher than 89. You might as well save yourself a couple bucks instead of using fuel that could foul your plugs.

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1984 1/2 GT350 (#842 Hatchback w/ T-tops), 302HO, Comp cams Xtreme Energy cam, Carter 625cfm carb, Weiand Stealth intake, MSD distributor, MSD coil, FMS 9mm wires, 1 5/8" MAC unequal shorties, 2 1/2" MAC Prochamber H-pipe, Flowmaster 2 chambers, KYBs, 16"x8" 4 lug Cobra Rs, Falken 245/45ZR16s

While on the topic of octane, can anybody tell me if a "point" of octane is one full number or one tenth of a number? For example, if I use an octane booster that is supposed to be good for 3 points with 92 octane does that make it 95 or 92.3? I have been doing some research on the web and have gotten mixed info. Some sites say a point is a whole number and others say it is a tenth, so I am confused. Thanks for any input... http://www.mustangworks.com/msgboard/cool.gif

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92GT all the free stuff and a few bolt-ons, lowered with Ebiach's and Koni's, Kenny Brown subframe connectors, lower G-brace and jacking rails. BBK upper and lower control arms, polyurethane bushings all around and Ken Bell blower, ram-air, 80mm mass air, etc.

3 points = 0.3

Pure marketing tactics. They hope people assume a point is a whole number. It's not. If it was I wouldn't be spending so much on racing fuel. I'd just fill up with 93 and throw a couple of bottles of booster in the tank.



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Craig
Supercharged 93 GT
Basically stock 93 Cobra
"I drive way too fast to worry about cholesterol!"

What a RIP OFF. 10 bucks for .3. Thats just horrible. I've also heard that they leave excessive carbo deposits.

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67'fastback-Edelbrock carb,intake,cam,valve springs.Rhode lifters, CompCam rocker arms, windage tray,cerama coated headers,dual flows with H-pipe, modded c-4,tci stall converter,perma cool electric fan,aluminum water pump,griffen aluminum radiator,accel 8.8 cable,wide cap distriburator,magnetic pick up,v-matic hurst shifter,edelbrock performer nitrous, carter electric fuel pump,ignitor coil,solid motor mounts,magna racing suspension,poly urathane bushings,under rider traction bars, comp. eng. s