Octane Rating

[Reginald West]

Can anyone tell me what the octane rating for 91 proof alcohol is ? Which produces the most horsepower alcohol or methnol ?


Reg

 

[Chevota]

No, but...

...I can see where this is going

-scott wile

 

[Reginald West]

Your right scott and its going there fast.


REG

 

[Razor]

Just get methanol.

 

[Reginald West]

Razor
I am using methnol but I am being told by other sources that ALKY is better which I have a hard time beliving.

 

[HellOnWheels]

In the Ethanol world 200 proof ethanol equals 100 % alcohol.

 

[Pablo]

Uh, Methanol is alcohol

and Ethanol is alcohol too

so is Isopropyl

 

[Reginald West]

Pablo
I agree. But is any form of it better than the other?

 

[HellOnWheels]

Uh, Methanol is alcohol

and Ethanol is alcohol too

so is Isopropyl

Well good!!

I read his post as asking for octane ratings!!

 

[79Sleeper]

Pablo
I agree. But is any form of it better than the other?

Do you see any of the Pro Stock or whatever Alky drag cars running on 100% denatured, Iso, or ethanol? Don't you think they would run whichever made the most power?

 

[Reginald West]

79sleeper
I guess thats your way of saying methnol is better. Thank you.

 

[norbs]

Well i am going to change the mixture to 70/30 methanol /water, as i have learned the hard way that pure methanol has a nasty pre-ignition property when run pure. you may make more power on it, but if it is going to cause pre-igntion, i need to reduce that from happening.

 

[Reginald West]

Norbs
Tell me more how much testing have you done with the water mix? have tried more or less water and what results did you get? Did you have to adjust the fuel map after adding water?

REG

 

[norbs]

I have always run 100% methanol, but i had pre-igntion with zero knock, Reg i have not added water to it yet, just reading about it so far. I a down to 50% duty cycle on 83's instead of 75-80 i usually run, so yes its a whole new fuel map you will have t build. I will try and find out the most info i can on mixing and the effects. I think i will be tuning to 10.5 a.f as a starter, but still pure methanol for now.


norb

 

[Razor]

If you spray just enough methano to quel detonation, you wont have pre-ignition.

If your timing is set up correctly, and are not bouncing off of rev limiters.. you wont get preignition.

I have sprayed my motor to death and never pre-ignited it. Altho I have customers with DSM's that had issues running twin 15's and bouncing off the limiter..

Keep your alky to suppress knock. Not try and over inject.

Get crazy with water.. you'll hydro the motor.

 

[Razor]

Razor
I am using methnol but I am being told by other sources that ALKY is better which I have a hard time beliving.

Alky=methanol

And the company Sunoco is the one calling it "Alky" Which is racing methanol= Sunoco Racing Alky

VP calls it M1

Both are methanol.

HTH

PS.. Whisky is also alcohol.

 

[HellOnWheels]

Do you see any of the Pro Stock or whatever Alky drag cars running on 100% denatured, Iso, or ethanol? Don't you think they would run whichever made the most power?

ALL of the car that raced in the Indy 500 this year was burning pure ethanol which has a rating of 105 octane.

I'm not sure but I believe methanol is 117 octane??

 

[Pablo]

Well good!!

I read his post as asking for octane ratings!!

He asked a two part question, the first part was what octane is 91 proof alcohol.

The second part was asking what produces the most power, alcohol or methanol. That is like asking what is stronger, wood or mahogany. So I made the clarification that methanol is an alcohol and that there are several types of alcohol perhaps helping him to be more specific in his question.

The question is still kind of vague even if we assume that "alcohol" refers to ethanol in his question. There are alot of factors involved in how much power is made with which alcohol. In the strictest sense, there is more power to be had from ethanol since it has more energy content pound per pound.
Since we are using it as a supplementary fuel and cooling agent, in actual practice, methanol seems to be more effective since you can use alot of it (low stoich afr throws off your mixture little) which compounds the benefits of its high latent heat properties. If you used isopropyl (for an extreme example) in the same quanitity you would have to greatly reduce the amount of gasoline in the chamber. This is removing a fuel from the chamber (gasoline) with higher energy content than alcohol that would also be absorbing heat from the chamber as it changes state.
Since methanol carries its own oxygen, it doesnt force you to reduce the amount of gasoline in the chamber to the same degree. So you've added alcohol to the chamber, an agent with a high latent heat in addition to close to the same amount of gasoline you allready had. The total energy content balances out to be probably greater than the isopropyl/gasoline mix, and, probably greater latent heat since you have more gasoline and alcohol alltogether. Despite the fact that isopropyl has much more energy content per gallon, the greater cooling effects of the gasoline/methanol and probably neglible difference between total energy allow methanol to win the day.

There is probably a long equation to tell you definitively how much more energy a specific lambda of a fixed amount of different types of alcohol mixed with a variable amount of gasoline
You don't need an equation to know that the richer the input afr is required for a given alcohol, the greater amount of heat it will absorb in the chamber for a fixed amount of alcohol and variable amount of gasoline to maintain the same lambda. In this case, methanol clearly wins hands down. That is making no mention of the fact that it has a much higher latent heat. Its a double whammy.

Ethanol is somewhat inbetween iso and meth in its energy content and latent heat and stoich AFR. It seems to me that there is a correlation between energy content the three. From what I have observed, it would seem to me that what is eliminating the knock in the chamber the most is the latent heat property of the fuel. Boost makes for more power and if you are knocking you cant run more boost. For a given amount of methanol you will absorb more heat than ethanol, and be able to run more gasoline which also absorbs heat. The result is alot more heat pulled from the chamber than ethanol and probably a neglible energy difference (If there are any chemists here that can work out the energy difference I would love to see that)

I am no chemist and am just going off of what I have observed in testing and from my own research online, Im sure I've goofed in how I've explained it somehow but that is what makes sense to me. If there are any chemists out there please chime in.


Proof refers to how much alcohol is in a beverage, the proof number is twice the percentage of the alcohol content measured by volume at a temperature of 60 °F (15.5 °C). So 91 proof means that whatever beverage he is thinking of using is only 45.5% ethanol, the rest is water. So if you want to accomplish the same thing as 91 proof alcohol, you can just get ethanol and mix it to where it is 45.5% alcohol and the rest water. Since alcohol is not flammable under 50% I would guess that the octane rating would either be infinite or pretty darn high.

 

[Reginald West]

Pablo

Thank you. Your post makes things alot clearer.



REG

 

[Alky V6]

Ethanol has more energy content per pound than methanol, but don't forget specific energy at stoich AFR. When each is burned using an equal amount of air at stoich mixtures, methanol has slightly more energy content. Methanol wins over ethanol in the latent heat of evaporization by a small amount at pound per pound comparisons, but increases at stoich mixtures. If your looking for a coolant for latent heat of evaporization value alone, water beats out methanol.

Now for the grey area. The advertised octane of methanol is 109 RON, 89 MON. Ethanol is 109 RON, 90 MON. These are numbers brought about by strict laboratory conditions. Both tests, to some degree, reheat the intake air after the fuel is introduced to nullify alcohol's latent heat of evaporization property. When alcohol's latent heat of evaporization is taken into account, in the real world, methanol's octane level is much higher. Using my experience with the fuel, I have calculated that the upper limit octane level for methanol is around 135.

I can tell you from experience (Go Boom! Boom!) that it is very true that methanol will preignite without any warning. The main factor that will get you in trouble is combustion chamber heat. There are many factors that will contribute to high combustion chamber heat. The initial overall engine temperature, cooling system efficiency, fuel mixture, igniton timing, boost level (big factor), exhaust back pressure, cam timing, static compression ratio, head design and material, spark plug heat range, spark plug material, carbon levels in the chamber, the balance of the injectors, intake manifold design (equal charge and coolant distribution), temperature of the fuel, efficiency level of the turbo and intercooler, ambient temperature of the air, air filter restriction, engine oil levels in the combustion chamber. Get all these tuning factors in line and you shouldn't have any problems.

About spark plug material. Do not run platinum plugs with methanol. Platinum acts as a catalyst when methanol is present.