Ideal % of E85 for Power?

[John Wallace]

The alcohol is denatured anyway.
The main reason is to raise the octane level higher without using the more expensive gasoline.
(same as gasohol/E10)

Using some gas might also make it able to be used on the road.
(gas tax)

[woody b]

The alcohol is denatured anyway.

What is used to "denature" it? (to explain my question) I use shellac on some of the musical instruments I make. "Real" shellac is made by dissolving shellac flakes in alcohol. (ethanol) Using "denatured" alcohol from a hardware store will work, but I get more consistent results using Everclear(180 proof grain alcohol sold at liquor stores). I was told that hardware store denatured alcohol was usually ~90% ethanol, with various "junk" to "denature" it, and make it undrinkable. I was told everything from acetone, methanol, MEK, or any number of things would be used to 'denature" it. I do know that when trying to use it for shellac the results vary greatly from can to can.

Several decades ago a few local "gasohol" manufacturers got busted for not using all of the yield from their stills for...... gasohol. I've never drank "gasohol" but their apple and peach brandy was good.

[Brian P]

Hey Everybody,
What is the ideal % of Ethanol for pump E85 to make the highest power?
Thanks, Craig

Since you have provided NO information on the application then I will give you the choice of three answers.

Situation 1: The vehicle in question is a standard production vehicle that is optimized for operation on gasoline (<10% ethanol) and is not a FlexFuel vehicle.

Answer 1: The ideal % of ethanol for pump E85 (with the balance being straight gasoline) to make the highest power is 0. In fact, the engine will probably not even start on E85, and if it does, it will run badly, if at all.

Situation 2: The vehicle in question is a standard production FlexFuel vehicle capable of running on straight E85 but it is also capable of running on 87 octane pump gasoline.

Answer 2: Straight E85, although I betcha your butt dyno won't be able to tell the difference.

Situation 3: The vehicle in question is a modified vehicle that has been fully optimized for use of E85 (i.e. much higher than standard compression ratio) and we are comparing it to an otherwise similar modified vehicle that has been fully optimized for use of 91-93-94 octane gasoline (<10% ethanol).

Answer 3: The E85 vehicle will run on straight E85, will make more power than the optimized-for-gasoline vehicle, and it will not be capable of running properly on gasoline any more. You will HAVE to run it on E85 because it would detonate itself into oblivion if you were to attempt to run it on pump 91 octane gasoline due to the much higher compression ratio that E85 will tolerate.

Did I cover it? Or is the situation something else, in which case ... clarify the question.

[INTMD8]

As others, not sure what you're looking for/what your combo is.

I tune a lot of forced induction LS cars converted to flex fuel, using a composition sensor.

On those, a big part of the additional power comes from the additional timing it will take on alcohol.

On a CTSV for example with 15-17psi boost will be around 19deg total on 93.

It will end up at around 25-26deg total and pick up 70-90rwhp a that point and this can be done at the 55-60% alcohol content. (starting in the 600-650 range on 93)

At that same timing level, raising alcohol content to the 90% range picks up a slight amount of power but not much.

Also at the 90% alcohol content range it will take a few degrees more timing without knock but again, not much gain.

So on the combinations I am used to tuning you will get 90+percent of the gains on 55-60% alcohol.

On higher horsepower engines (1000+rwhp) I like to run 85% plus for additional safety and do not run as much total timing as the moderate horsepower stuff.

[modok]

Ethanol is "denatured" with methanol, or gasoline, or perhaps other things, most of them flammable.

[Rick Finsta]

There are several types of denatured and specially denatured ethanol. Methanol, Toluene, and Benzene are the most common constituents I've seen in the chemical production industry.

Mike Croley, do you have any insight into where the detonation resistance of the ethanol levels out? I've read literature showing even detonation resistance above around 55%, which incidentally is the lowest allowable mixture at a pump in America. Not sure about the methodologies as they apply to racing engines, though.

[CraigG.]

Sorry guys about the lack of clairity - I have been involved with family issues.
Combination:
72 GTO - Race weight 3400 with me
Elevation 980 Feet
465 and 12 1/2 to 13 to 1
455 bored .040 over
Bore … Stroke…
Hand Ported E-heads - '1999 - '2000
Heads Flowed 331 int. and 235 ext.
72 CC milled .060
Zero Decked
Flat Top Ross Pistons

Solid Roller at 276 / 279 at .050 and .635 lift
Installed at 104
Comp Cams - Grind# P8 4028B / 4049B R 108.0
Intake Exhaust
Valve Adjustment .020 .022
Gross Valve Lift .631 .630
Duration @ .020 Tappet Lift 312 316

Valve timing Open Close
@ .050 INT: 30 BTDC 66 ABDC
EXH: 67 BBDC 31 ATDC
108.0 Intake Center Line
Intake Exhaust
Duration @ .050 276 279
Lobe Lift .4210 .4200
Lobe Separation 108

MSD 6AL 2
MSD Billet Dist.
Advance Locked at 33 degrees

Northwind intake - 1050 dominator

"2 Hookers Headers
Turbo 400 with a brake
"8 4500 stall on the brake - Butler design
3.73 gears with MT 10.5w x 28 slicks

Thanks Guys

[pdq67]

I have posted this several times in the past.

Gary, (aka, GOSFAST), has said that there are few northeastern guys with dedicated blown engines that run E85 up to a theoretical, (blown), CR of above 17 to 1 fine. The tune has to be spot-on though!

I figure that the OH radical breaks off and recombines to form water that steams which cools the combustion chamber enough to allow the engine in question with these extreme CR's not to detonate.

As for practicality, most guys run E85 at 13 to 1 CR but it is good to 14 to 1. As always, jmho.

I have plant toured two of MO's ethanol plants and the tour guides said that they denatured the raw stock, (I think 98%?), with unleaded gasoline. Malta Bend and Macon, MO...

One thing that most do agree on is to buy a testing kit so that you know for sure the percent ethanol in pump gasoline.

pdq67

[Mike Croley]

There are several types of denatured and specially denatured ethanol. Methanol, Toluene, and Benzene are the most common constituents I've seen in the chemical production industry.

Mike Croley, do you have any insight into where the detonation resistance of the ethanol levels out? I've read literature showing even detonation resistance above around 55%, which incidentally is the lowest allowable mixture at a pump in America. Not sure about the methodologies as they apply to racing engines, though.

The answer to that question is partly based on exactly what E-85 you're using. E-85 blended with 15% of 87 octane pump gas is going to have very different detonation resistance to a blend that uses 15% race gas for instance. And as we've been discussing, the quality of the ethanol can also vary which will give you less detonation protection. I know of racers who use top quality E-85, like the Renegade Pro Race E-85 with CR of 16:1. Of course in order to do that, the timing has to be backed down. So you're giving up some potential power to be able to make the motor live.
Every engine combo, even ones that are supposedly identical, has a different octane requirement because tune ups are different, conditions are different, engine loads are different. So it's difficult to say with any accuracy at all what the ultimate detonation thresh hold might be.

[Mike Croley]

There's also the question of where peak power is produced with E fuels. Some say anything above 70% ethanol content shows little or no gain in performance. Others insist that their combo makes the best power at 98% ethanol. Again, the combo, the tune up, the conditions, and the engine load are bound to have an influence.