compression vs octane rating...

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novice
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Joined: Tue Feb 24, 2009 10:20 am

compression vs octane rating...

Postby novice » Tue Mar 26, 2013 8:52 pm

just got some info that the e85 fuel in this area is really just e70. I was thinking about converting to the e85, but now that may be out the window. what octane rating do you need to run 11.6/1 compression and what octane is e70? or do some of you guys mix your own, say 2 gal race fuel and 2 gal pump or e98 and e70? I know the answer is to run the race gas but that is costly, and the reason for the e85 in the first place. thx...novice
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oldyeller
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Location: Oswego,KS

Re: compression vs octane rating...

Postby oldyeller » Tue Mar 26, 2013 9:48 pm

E70 is 105 octane,way plenty for your compression......You can buy a tester that makes it simple to tell what percentage E they have at the pump...The tester is inexpensive and easy to use,takes the guessing out of it.....If you want to mix your own you can mix one gallon of regular to 4 gallons of E98...Comes out real close to 85% everytime.....
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The older I get,the better I was..........
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71z28camaro
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Re: compression vs octane rating...

Postby 71z28camaro » Wed Mar 27, 2013 6:42 am

novice wrote:just got some info that the e85 fuel in this area is really just e70. I was thinking about converting to the e85, but now that may be out the window. what octane rating do you need to run 11.6/1 compression and what octane is e70? or do some of you guys mix your own, say 2 gal race fuel and 2 gal pump or e98 and e70? I know the answer is to run the race gas but that is costly, and the reason for the e85 in the first place. thx...novice


If the pump says e85 and its testing out to e70 they do that through the winter months. It will go back up to e85 in the next month. With only 11.6 comp. not sure thats enough to take advantage of the e85 fuel route. Mixing alittle race gas with some 93 octane pump gas may be a better way to go.
novice
Posts: 187
Joined: Tue Feb 24, 2009 10:20 am

Re: compression vs octane rating...

Postby novice » Wed Mar 27, 2013 2:10 pm

John, at jdr performance tells me they keep it at e70 year around, have to go to waynesville to get the e85, go figure. was going to get my carb set up for the e85, when they warned me. good folks over there. may get it done anyway and run the e70, but who knows how long they will have even that. what is this stuff used for, other than racing and maybe supplimenting the farmers? ...novice
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oldyeller
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Re: compression vs octane rating...

Postby oldyeller » Wed Mar 27, 2013 6:17 pm

Your car will go quicker and run cooler than it does on race gas....Just depends what you want.....
The older I get,the better I was..........
Draginhall
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Re: compression vs octane rating...

Postby Draginhall » Wed Mar 27, 2013 6:53 pm

We changed our car over and picked up 3 tenths over Sonoco 112. We run a 383 small block approx 13 to one compression and a two barrel carb. Our friend Paul Cooper also changed over on a 4 barrel and picked up two and half tenths and 5 miles an hour in the eighth. We both were running C%S aerosol carbs on race gas so we did not have junk carbs running on race gas. The new Kum N Go at Springdale started off with E85 last year and last month had E76. Our car runs great on E76. If you have the right person work on your carb it is great and no problems at all for us all last year. Car sat all winter and all we had to do was pump the accelator several times and it fired up and ran great. Terry Hall
novice
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Re: compression vs octane rating...

Postby novice » Fri Mar 29, 2013 1:55 am

thanks for the replies guys...now all I have to do is figure out which way to go, leaning toward the e70...novice
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500s10
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Re: compression vs octane rating...

Postby 500s10 » Fri Apr 19, 2013 10:52 pm

has anyone switched from methanol to ethanol woundering how it effected et
JDR Performance
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Re: compression vs octane rating...

Postby JDR Performance » Mon Apr 22, 2013 9:01 am

You'll lose a little bit of HP and TQ assuming that both carburetors are perfect. If the methanol carb isn't and the E-85 carb is, you may not lose anything. If the methanol carb is good and the E-85 carb isn't, you'll slow down some.
Regarding the fuel blend, it isn't that E-70 (tested a new batch from Kum n Go) won't run, you just won't see the benefits you'd see with E-85 unless you're running a low compression motor. If you're going to set a car up for E-85, it's nice to at least be able to use the right fuel. The Westgate gas station in Waynesville blends the fuel at the nozzle, and has been right at 85% so far. You'll want to run a couple of gallons out first in case the person before you got E-20 or something. I've been doing E-85 builds since the fuel first came out around '2000, and send them all over the country. This area is the only place I've heard of where the fuel is 70% at the pump during the summer. Perhaps the people making that decision will remove their heads from their posteriors someday. In the meantime, there is Waynesville or blending your own fuel. BTW, if you see it at 70% at most stations but it tests at 75% at one that gets fuel from the same supplier, it may have water in it so be careful.

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