I am running the Buschur alcohol injection kit on my Evo. I have heard that methanol is very corrosive and not recommended with the Buschur/SMC kit. However, I also heard that methanol is better for making power. It is certainly cheaper.

 

Both have high octane ratings, although ethanol is a little higher. FWIW, IRL cars are switching from methanol to ethanol for 2007, and they don't expect any significant changes in power levels or otherwise, so one looks about as good as the other.

My reservations with denatured ethanol concern the compounds used to denature it (make it unfit to drink). There are at least several ways to do this legally, and you'd want your denatured mix not to be denatured with anything that would reduce its octane rating and/or leave residue.

Also, the stoichiometry for both is a little different (6.4:1 for methanol, 9.0:1 for ethanol), so whichever you choose for dyno tuning your car, you'd probably want to stick with it.

 

BOth are 101 octane. Methanol is wood based...

 

FWIW, octane is measured in different ways, and while I've seen ratings for as high as ~110 for methanol and ~115 for ethanol, the R+M/2 method seems to show them both around 101 or so (as noted just above).

And oh yeah, a lethal dose of methanol for about 50% of people is ~30mL (1 oz), so be advised!

 

So, denatured alcohol (ethanol) has higher effective octane rating. Works out great for me since I am custom tuned with it. Thanks.

 

Yup, alcohols typically have high sensitivities, i.e. high RON (~115) and low MON (~90), so you need to be careful with your tuning if alcohol is a significant part of the fuel.

The common denaturants for ethanol are methanol and pyridine (no octane problems there), kerosene, diesel, and pine oil (not so good), and stuff like bitrex (used in small quantities), so, yeah, you can't be sure of what you're getting.

And while methanol was first produced by dry distillation of wood, it hasn't been made that way in years. Nowadays it's made from natural gas -- much cheaper.

Dave H.

 

The biggest difference between the two (in the context of this discussion) is the available energy.

Methanol: ~62,000 BTU/gallon
Ethanol: ~86,000 BTU/gallon
Gasoline: ~125,000 BTU/gallon

Ethanol will produce more power per a pound or gallon than methanol.

I was also under the impression that ethanol is more corrosive but I may be mistaken.

 

Does that imply that running the car stoich, ethanol will deplete faster than methanol?

 

No, in fact more slowly. Remember, that is 9 units of air to a unit of ethanol. It's probably the principle reason IRL is switching to ethanol. More power per pound of fuel effectively means better fuel consumption rates at a fixed horsepower level.

 

That's true, although when the difference stoichiometry is considered, the advantage is only slight.

 

Now here's one thing that interests me...

Methanol and ethanol appear to give right about the same amount of power. Methanol has a stoichiometry of 6.4:1 and ethanol 9.0:1. This seems to indicate that ethanol should give the same results with roughly 30% less consumption (the reservoir lasts longer).

As we pointed out above however, you'd have to know the quality of the ethanol you'd be getting. Also, that ethanol may contain 10% or so water (since ethanol and water make an azeotrope), which could be a factor as well.

 

Not to mention both ethanol and methanol are hydroscopic so your fuel will absorb water until it becomes saturated. Does anyone know what that percentage is?

 

Methanol will absorb moisture from the air (hy[g]roscopic). One way to prevent this is to add a little Acetone (<10%), which also has value as a fuel.

Ethanol cannot be made more pure than ~95% or so from distillation. Because of the way ethanol and water interact, there will always be at least 4-5% water. Ethanol is also very hygroscopic, but for the reason I just mentioned, will already contain at least 4-5% water when it's put into the container.

 

The more I look into it, the better methanol looks for performance use. Not because methanol appears to be better than ethanol (if anything, the opposite seems to be true), but because getting virtually 100% methanol is no problem.

On the other hand, the only cost-effective ethanol is denatured ethanol, which looks to be only ~80% ethanol, the rest frequently being methanol, isopropyl, other compounds, and of course, water. The only way around it is to buy absolute ethanol, which is quite pricey.