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Thread: What Octane

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    Default What Octane

    1984 crossfire fuel injection (sort of) I assume the proper gas for this year is 87 Octane. Don't have the owners manual and the service manual does not seem to address this issue. Comments please

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    I wouldn't assume anything. My '90 requires premium, as stated by fuel filler, "Premium Fuel Recommended."

    I skimped once and used regular 87 octane and she didn't like it at all. NOT AT ALL!

    When in doubt, use the good stuff. She will appreciate it(and so will you.)

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    Owners manuals can be found on EBay, that's how I found one for my 86. The 86 runs fine on 87 octane but it's a cruiser so it's not being pushed hard. No racing, no pinging, just hits the road and runs just fine.

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    87 octane is what it was designed for. Higher octane was not required until 1987 I think.

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    Just me its a Corvette it gets the best!! Just part of owning a sports car.

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    It might make you feel good but the car couldn't care less.

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    Quote Originally Posted by Wegone View Post
    Just me its a Corvette it gets the best!! Just part of owning a sports car.


    FWIW higher octane fuel in not a better fuel, it just has a higher octane rating number, and it does accellerate carbon build up.
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    It is a double edged sword; too high or too low is bad. The best answer is use what the engine manufacturer says to use.

    IMO, this article is very informative on the subject.
    Obviously, PCM cold enrichment strategy is required even in the case of a brand-new engine because sufficient vaporization of atomized fuel on the backs of cold inlet valves is impossible to achieve. But the inevitability of carbon buildup accumulating on the valves will eventually result in cold (and sometimes even warm) engine performance issues such as stumble, sag, stalling, etc. Injectors spray their fuel volume very close to the beginning of an intake stroke; itís only later in the stroke that the inlet valve actually opens in order to draw air and fuel into the cylinder. Small portions of the atomized hydrocarbons sprayed by injectors onto the backs of the closed inlet valves will invariably be absorbed and transformed by heat into additional activated carbon residue.
    MOTOR Magazine Article | MOTOR Information Systems

    Personally, I buy Top Tier gasoline because it has more detergents than bargain gasoline.
    Whoosh, and blur

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    Quote Originally Posted by kpic View Post

    Personally, I buy Top Tier gasoline because it has more detergents than bargain gasoline.
    But additives has nothing to do with octane rating- the OP's sole question.

    We just need somebody to mention ethanol and we'll have the gasoline trifecta.

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    Quote Originally Posted by Vettehead Mikey View Post
    It might make you feel good but the car couldn't care less.
    Quote Originally Posted by LLC5 View Post
    FWIW higher octane fuel in not a better fuel, it just has a higher octane rating number, and it does accellerate carbon build up.
    OK my car does not run good on low octane with an 11.5 compression ratio. I'll step out now!!
    Steve

    1991 ZR-1 # 118 Quasar/Black SW Headers/Corsa-3:73 gears-Haibeck-500HP/350

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    Quote Originally Posted by Wegone View Post
    OK my car does not run good on low octane with an 11.5 compression ratio. I'll step out now!!
    The OP's car is 9:1, like all '84s. That's the difference.

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    Quote Originally Posted by Vettehead Mikey View Post
    The OP's car is 9:1, like all '84s. That's the difference.
    Original post

    Quote Originally Posted by Heyblue View Post
    1984 crossfire fuel injection (sort of) I assume the proper gas for this year is 87 Octane. Don't have the owners manual and the service manual does not seem to address this issue. Comments please
    My response

    Quote Originally Posted by Wegone View Post
    Just me its a Corvette it gets the best!! Just part of owning a sports car.
    I also have an L83 & LT1 they also get Hi Test. BP 93 octane. Did not mean to start a disagreement.
    Last edited by Wegone; 08-22-15 at 11:41 AM.

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    Quote Originally Posted by Wegone View Post
    OK my car does not run good on low octane with an 11.5 compression ratio. I'll step out now!!


    Agreed, with high compression engines designed to run on high octane you definitely want to use it. Engine power and fuel mileage will be decreased (sometimes dramatically) with the usage of a lower octane fuel rating in and engine designed for high octane usage. Ignition timing will be pulled and fuel maps can be altered by the PCM to account for the detonation that will occur with low octane fuel in any engine designed to run on high octane. Basically use the octane rated fuel that the engine builder or manufacturer (OEM engines) require. Using higher octane fuel than is needed will only get you slightly faster carbon build up and a lighter wallet.
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    Quote Originally Posted by Wegone View Post
    Did mean to start a disagreement.
    I'm sure you meant 'didn't' mean to start..........

    Quote Originally Posted by LLC5 View Post
    Using higher octane fuel than is needed will only get you slightly faster carbon build up.
    Never heard that one before. Why would this happen? We know that millions of drivers use higher octane fuel than required thinking 'it's better' but I've never heard about it causing carbon deposits.

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    Quote Originally Posted by LLC5 View Post
    FWIW higher octane fuel in not a better fuel, it just has a higher octane rating number, and it does accellerate carbon build up.

    Interesting... I was always under the impression that carbon build up was a direct result of improper tune, air fuel mixture, oil consumption.

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