Octane?
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Octane?

  1. #1
    Member hollbrow's Avatar
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    Default Octane?

    What minimum octane #'s would you experienced guys want to run on a moderately cammed 454 BBC in a jet boat with a compression ratio of around 11:1? I have access to 110 & 112 octane race fuel and it's rather expensive. I have never run the boat much- (twice in 8 years), so in the past it has not been that big a problem. With todays fuel prices, its a problem. I have plans to pull it down and drop the compression to pump gas levels next winter but I want to come up with the most inexpensive concoction I can to get me by until then. I'm thinking some sort of cocktail composed of race gas, octane booster and premium unleaded should be worth my time to mix up. Any sugesstions?
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    Senior Member Widetrack's Avatar
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    What heads do you have cast or Alu.! A mix will work but you can leave off the octane boost it doesn't do all that much! I believe I read that added to 92-93 octane that it only increases it to 92.2-93.2 or so! A 50/50 mix would cover you! WT


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    alum heads i'd run a conservative timing curve on 93octane, if they're cast iron heads i'd run 1/2 93 octane, 1/2 avgas

    Dare to be different, if it turns out great you can claim you planned it that way.

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    Member hollbrow's Avatar
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    They are cast iron heads- large oval port with a bit of work done on them. Yeah- I don't have that much faith in the octane boost. I have read that when the octane boost container says raises octane by 8 points- that it really means 8/10ths of a point. I used to have access to Avgas back some years ago- that is one reason I originally built the engine with compresion in it. That ain't happening at $8-$9 a gallon these days for race fuel. If you ain't got a plane sitting out on the tarmac these days No Gas For you!
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    Senior Member CK7684's Avatar
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    I'd run it 1/2 & 1/2...I read an article about octane boosters and most don't work at all. The article said only one brand worked, but they didn't reveal which one!!
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    set it up on E85. it will cost about 400 up front to do it. then it's 2.85 a gal to fill up.
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    I have used the CAM2 and similar stuff in the past- but never really knew if it helped. The octane boost stuff isn't cheap either.

    So if I mixed 1 gallon of 112 with 1 gallon of 93 I guess that would be 112 + 93 = 205
    and 205/2 = 102.5 octane? That sounds reasonable. I'll try it.
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    Quote Originally Posted by baker pickle fork View Post
    set it up on E85. it will cost about 400 up front to do it. then it's 2.85 a gal to fill up.
    Pay special attention to this ^ post and you'll be glad for a long time to come!
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    Quote Originally Posted by baker pickle fork View Post
    set it up on E85. it will cost about 400 up front to do it. then it's 2.85 a gal to fill up.
    ^^^^^^^ great advise right there

    Dare to be different, if it turns out great you can claim you planned it that way.

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    Member hollbrow's Avatar
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    That is an option I suppose. E-85 is not real easy to find where I am at. Although E-85 does have an inherently higher octane rating and is a good fuel I'm not really on the E-85 bandwagon- I'm kinda agree with the opinion that the production of it has greater disadvantages than the advantages seen from using it as a fuel.
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    Quote Originally Posted by hollbrow View Post
    What minimum octane #'s would you experienced guys want to run on a moderately cammed 454 BBC in a jet boat with a compression ratio of around 11:1? I have access to 110 & 112 octane race fuel and it's rather expensive. I have never run the boat much- (twice in 8 years), so in the past it has not been that big a problem. With todays fuel prices, its a problem. I have plans to pull it down and drop the compression to pump gas levels next winter but I want to come up with the most inexpensive concoction I can to get me by until then. I'm thinking some sort of cocktail composed of race gas, octane booster and premium unleaded should be worth my time to mix up. Any sugesstions?

    av/91 50/50 should work fine for 11.1 ...best way to go for the $$$$$... you don't really have the compression to benefit from race gas ...

    av gas / 91 pump gas gives you the octane u need from the av / the flash point from the 91 . also known as POOR MANS RACE GAS .
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    Default Octane

    I have a 11.5:1 BBC (LS-6) with iron Merlin heads, 850 DP Holley, Crane hydralic flat tappet cam in the .575 lift range. I am running 93 pump gas with Torco Accelerator (it will give an 11 pt. octane bump at one quart per 10 gallons of gas) or 104 octane starting with 93.

    Another combo that works really good in my motor and is a bit cheaper, is mixing above mixture (2:1), two gallons with one gallon of E85. Burns cooler and cleaner and, no carb changes needed in my setup.

    I get the Torco Accelerator 6 quarts at a time for $90.00 or $15/quart.
    Can buy 5 gallons for $225

    Google Torco accelerator and check it out. Not ordinary octane booster.

    I also had a 13:1 LS-7 with a modified E85 850 Holley in a Sanger v drive running E85. I worked very nicely. I had to go to the biggest squirters and a 75cc methanol pump in the secondary but it ran great. Had touble getting oil temp up until I added a Harmin marine thermostat. E85 runs very cool.

    Last edited by ak.hunter; 05-11-2010 at 12:52 PM. Reason: add add more
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    if the motor runs cool, you don't have a shitload of timing in it and your not legging the thing all the time just run good 93 in it if it pings just mix 112 four to one. it'll give you some lead and protect your valves ok. (4-1) 93four 112 one
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    Senior Member 2002CP19's Avatar
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    Quote Originally Posted by ak.hunter View Post
    I have a 11.5:1 BBC (LS-6) with iron Merlin heads, 850 DP Holley, Crane hydralic flat tappet cam in the .575 lift range. I am running 93 pump gas with Torco Accelerator (it will give an 11 pt. octane bump at one quart per 10 gallons of gas) or 104 octane starting with 93.

    Another combo that works really good in my motor and is a bit cheaper, is mixing above mixture (2:1), two gallons with one gallon of E85. Burns cooler and cleaner and, no carb changes needed in my setup.

    I get the Torco Accelerator 6 quarts at a time for $90.00 or $15/quart.
    Can buy 5 gallons for $225

    Google Torco accelerator and check it out. Not ordinary octane booster.

    I also had a 13:1 LS-7 with a modified E85 850 Holley in a Sanger v drive running E85. I worked very nicely. I had to go to the biggest squirters and a 75cc methanol pump in the secondary but it ran great. Had touble getting oil temp up until I added a Harmin marine thermostat. E85 runs very cool.

    Torco works! Used to use it in my Cobra.
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    Hold it firmly on the ground, a few pelvic thrusts should do the trick. If not repeat till satisfied!
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