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Gas mixed with Race Fuel ?

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Old 07-06-2010, 05:01 PM
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If your engine is designed to run on 93 octane and you mixed the fuel and ended up with a higher octane say like 95 or 96could it actually hurt anything?.....would it hamper performance?
Dont worry Mark......you still have them covered this weekend at JOTJ's. The V's anyway.
Seriously, higher octane than you need just ends up as carbon on your transom. Wont hurt anything, just doesnt burn completely. Hot air temp's and high humidity will make your motor lay down more than higher than needed octane. I have heard some folks say because of the incomplete combustion of the higher than needed octane you are not getting as much horsepower as you would with lower octane fuel burning more completely. Never noticed it in our 700's though.
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Old 07-06-2010, 05:06 PM
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If your engine is designed to run on 93 octane and you mixed the fuel and ended up with a higher octane say like 95 or 96could it actually hurt anything?.....would it hamper performance?
It would idle really good, but under load or higher rpm performance would suffer. Higher the octane number, harder to burn. The opposite of detonation. Low octane fuels explode before piston is in optimum position of stroke. Higher octane -harder to explode. Hope that helps maybe not the best description but that how it works................................Rjr.......... ...............................
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Old 07-06-2010, 05:43 PM
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So it's better or safer to run higher octain fuel then lower?
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Old 07-06-2010, 06:23 PM
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So it's better or safer to run higher octain fuel then lower?
Octane less than needed by the motor and well...big check writing time may rear its ugly head! The higher the octane, the safer the motor. Octane greater than needed for the motor, the lower the power...but I doubt I could actually feel the difference in the boat's performance. In reality, buying too much octane is money that needs not to be spent...but it isn't "bad" in the sense of damaging a motor. On the flip side, if some claims higher octane than needed will increase performance...well, get a second opinion!

That said, the ratings on fuel pumps is not absolutely nescessarily an iron clad guarantee. So, I gladly err a bit and buy slightly higher octane than the motor needs. Especially if the motor is going to see tough duty. For example, when I fuel my tow vehicle that "needs" 89 octane, I will put in higher octane fuel if I know I'm going to tow a large/heavy trailer with that fuel.

On ocassion, I have been forced to buy 89 octane for my boat motors that "need" 92 octane. On those occassions, I avoid letting the blowers develop much boost for any length of time. Ditto for burning off a tank full of stablized fuel that has been in the boat during winter storage.
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Old 07-06-2010, 07:00 PM
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Dont worry Mark......you still have them covered this weekend at JOTJ's. The V's anyway.
Seriously, higher octane than you need just ends up as carbon on your transom. Wont hurt anything, just doesnt burn completely. Hot air temp's and high humidity will make your motor lay down more than higher than needed octane. I have heard some folks say because of the incomplete combustion of the higher than needed octane you are not getting as much horsepower as you would with lower octane fuel burning more completely. Never noticed it in our 700's though.
thanks Randy and Robert Jr......I am little suspect that the "mishap" that I experienced on the Jammin run last year may have been the result of less than rated octane fuel....I was considering adding some 102 aviation fuel to insure against this happening again.....sounds like if the mixture was a little high on the octane side it may hamper performance slightly but at the same time provide a little insurance....am I reading this right?
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Old 07-06-2010, 07:12 PM
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.....sounds like if the mixture was a little high on the octane side it may hamper performance slightly but at the same time provide a little insurance....am I reading this right?
Yes and no..... If your in the ballpark, it shouldn't really cost you anything powerwise if your a little over on the octane, say 96~98 when your after 93. Now if your running 112 in your 89 octane motor, your probably leaving a bit on the table with the slower flame front (gas burns, it doesn't explode if the octane right).

The piece of mind is worth much more the miniscule loss of power, especially if your running hard
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Old 07-06-2010, 10:43 PM
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thanks Randy and Robert Jr......I am little suspect that the "mishap" that I experienced on the Jammin run last year may have been the result of less than rated octane fuel....I was considering adding some 102 aviation fuel to insure against this happening again.....sounds like if the mixture was a little high on the octane side it may hamper performance slightly but at the same time provide a little insurance....am I reading this right?
True "aviation Fuel" is formulated to burn at altitude not sea level. Check With AED Performance on J.D. Pike at willis rd.Richmond,Va They sell 102 and 106 octane race gas by the barrel. Blend it 3:1 3 parts pump gas to 1 part race gas will keep you safe. In other words don't buy it at the airfield!........................................R jr...................................
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Old 07-06-2010, 11:11 PM
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to get to 93 octane, use 25 gallons of 102 for every 75 gallons of 90
Exactly. A 1:3 ratio will give you a solid 93 octane. The 90 octane is minimum octane it can be(as long as you trust them). Most likely it is more like 90.1-90.5 octane

AV fuel will be fine as long as its mixed with some gasoline.

Last edited by Griff; 07-06-2010 at 11:14 PM.
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Old 07-07-2010, 08:11 AM
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True "aviation Fuel" is formulated to burn at altitude not sea level. Check With AED Performance on J.D. Pike at willis rd.Richmond,Va They sell 102 and 106 octane race gas by the barrel. Blend it 3:1 3 parts pump gas to 1 part race gas will keep you safe. In other words don't buy it at the airfield!........................................R jr...................................
Nothing wrong with AvGas. Pump it into 55 gallon drums right at the airport. Not going to start the AvGas war, its been beat to death already. Ran it straight in 2 strokes and 4 strokes, also blend it with regular gas. Runs fine. If you want to know what octane you are
blending, you can go here.
www.bazellracefuels.com/Calcs/OC1.htm
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Old 07-07-2010, 08:19 AM
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Nothing wrong with AvGas. Pump it into 55 gallon drums right at the airport. Not going to start the AvGas war, its been beat to death already. Ran it straight in 2 strokes and 4 strokes, also blend it with regular gas.
LOL. I've been running 33% AvGas in my boat for the past 3 and a half seasons with no issues whatsoever. It is very important to add 2 ounces of Marvels mystery oil to every 5 gallons of the AvGas. Runs good and smells even better

I also run it in my lawnmower, Gator, My wife's Honda Ruckus, my old Corvette and everything else that can get messed up from the ethanol getting old.

I also treat every ounce of 93 octane fuel that goes into all of the above with the valvetect additive....the price of it seems small when chit isn't blowing up!!!
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Last edited by OldSchool; 07-07-2010 at 09:14 AM. Reason: Added Valvetect
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