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Old 06-27-2012, 09:12 AM
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Ask me about Ethanol

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Originally Posted by Mojo56
You are one brave man here... taking a stand in favor of the boogie man...E85.

Be ready for the naysayers...
Have already had plenty of run ins with the naysayers, thing is most of them have no first hand experience with ethanol. I have first hand experience and have been running it for years, building carbs, engines, and not using anything exotic, just slightly modified stock stuff. Usually modified with a drill bit.

You hear or read stuff about how horrible it is, but really that is all just BS. The stuff flat works.

What octane an engine needs depends on a bunch of things. Chamber shape, bore size, material the head is made of, quench, piston design, cam specs, altitude, ambient temperature, any oil in the chamber and ignition timing all play a big part.

All aluminum modern engines like the LSx engines can utilize more compression on pump gas, older engines with iron heads need more octane for the same compression. Premium 93 wont work at 10.5:1 with most older engines that are all iron, even when you retard the timing to the point where it has no power anymore. It needs more octane than that, and there isnt any getting around it.

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Old 06-27-2012, 09:26 AM
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my engine is 11.2:1 and I mix 5 gallons of 110 octane with 10 gallons of 93 octane to keep it happy. I got smart and bought a 55 gallon drum with an electric pump, this is where I keep my 110 octane fuel. I go straight up to our local dragstrip and fill it up, because i'm buying 55 gallons at a time, I end up getting it for about .40 less per gallon.
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Old 06-27-2012, 10:00 AM
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Cans of octane booster are a waste of time. If it advertises a 3 point gain when used in recommended amount per gallon - that is really only a 0.3 gain ., ....but they don't want you to know that. Your 91 octane would only become 91.3 .

Another vote here for E85 if you can get it in your area or are willing to blend your own using a barrel of E98. I know several racers in my town using it in street or street/strip cars with no problems and noticable benefits in power and easier engine cooling. Getting ready to go E85 myself on a 13.5-1 comp 406 SBC, my chosen carb is at QuickFuel Carberaton right now getting the correct boosters installed to properly match up to E85 (950 Holley).

If you don't want to go E85, the race gas/pump gas blending is an easy alternative as mentioned. 11-1 with old Fuelie heads will be fine on the 20-40% blend as by F-Bird. I'd expect with ignition and carb properly tuned the 20% figure will be fine.

A note on blending--- a 50-50 mix of 87 pump and 110 race actually comes out higher than the math would suggest. Math says 98.5 octane for this mix, but because race gas has so much lead in it, the real mix is actually closer to 100 octane---a little real tetraethyl lead goes a long way, you get "octane creep" in the mix.
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