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Thread: Too Much Octane???

  1. #1
    tittyman
    454, dual carbs, 12:1...10 gallon tanks..if you run straight race fuel 110..is that too much octane and can cause the motor to not run as well..Second Question..if it is, about what octane level would be best (mixing 110 with 92)..

  2. #2
    VDRIVERACING
    More octane means a higher temperature needed to ignite it, that's why it's less likely to pre-ignite(detonate), but never heard of that downgrading performance. I AM NOT AN EXPERT, but my experience is that it's just a matter of safely running the least octane needed to save cost.
    12:1 is pretty high, and the engine builders I know advise against mixing fuels (although you'll no doubt hear that a lot of people do it). You might be OK with avgas which is 100+ octane, and keep an eye on your plugs for signs of detonation. Otherwise stick with the 110 and not worry about it.

  3. #3
    centerhill condor
    do yourself and engine a favor...spend the money and buy the race gas. Heck at today's prices you're only adding a buck or two to the price.

  4. #4
    tittyman
    You hear about a lot of guys mixing fuels..I was just told by a guy that has a high performance motor that you should not run 110 in a motor that could run safely on say 96-98..said it's not a good thing to do..never heard that before.
    Again if you have 12:1 what is the good octane range to be in..
    I know to some of you it sounds like a dumb question..just don't want to f**k up my motor..you guys always give good advise..this is the place to..

  5. #5
    VDRIVERACING
    Where are you gonna find 96?

  6. #6
    curtis73
    You're fine. A motor will start to detonate and lose power (not to mention destroy itself) if you use too little, but for all intents and purposes there is no such thing as too much.
    If you combo needs 91 for instance, it will run just as well on 91 or 110.

  7. #7
    tittyman
    Thanks Dragboats....Just what we talked about...In reply to one of the above posts..."how do you get 96"..I think you can get any number you want from say 92-110 by mixing the correct amount of boost in with the correct amount of fuel..or by adding 110 to your 92 octane..the formula to figure this out is
    R+M divided by 2. So if your boat runs clean on say 96 or 98 octane you can attain that number. It's less expensive than just buying all race fuel. In respect to the post that wants to run 100 octane aviation fuel..talked with a charter pilot friend..he said don't run aviation fuel because airplane motors are designed to run a much lower rpm and the ignition factor is way lower than a high performance boat motor. This is all new to me..never had a high compression motor..just want my boat to run right..thanks again Dragboats for the Terry hookup...

  8. #8
    Taylorman
    There are tons of people running avgas with no problems. I have a friend with a 12:1 motor running on avgas no problem.

  9. #9
    tittyman
    What is the price of avgas with race fuel..thanks..

  10. #10
    mostly crue
    to find the best fuel for you try VP fuels site. they break it down for you.
    They also rate their octane differently. I think its vpracingfuels.com.
    As far as mixing fuels, are you in Calif.? If you are the fuel in oxygenated, this will cause a chemical lean condition.so

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