99% Isopropyl alcohol as fuel additive?

Status
Not open for further replies.
Joined
Oct 9, 2007
Messages
931
Location
OR
I happen to have 10 spare gallons of 99% anhydrous isopropyl alcohol with no particular use. I'm wondering if I should use this as a fuel additive? I know that's all that "Heet" fuel dryer is made out of. Would it be really bad to add more alcohol on top of the 10% ethanol we already get? Could I use as an octane booster? The jeep has been pinging a little on 87 lately...

I remember once I was trying to start my lawnmower on old/wet fuel. It wasn't gonna happen. So I dumped a bottle of 91% rubbing alcohol into the gas tank to soak up the water, but, the engine actually ran great on the mix...probably about 50/50. It just so happens I was going to take the head off and replace the gasket anyway, and when I did, it was REALLY OBVIOUS that the big dose of alcohol had knocked off a lot of built up carbon. I wonder what the max safe ratio would be? Does this stuff eat rubber like ethanol and methanol?
 
What does that 1% consist of?
Isopropyl is not as horrible as methanol for corrosion and problems.
It has high octane, but you'd have to mix a lot to get meaningful increases.
Since the gas probably already has 10% alcohol in it, why not play it safe and add enough of your own to go up to 15% total [add it at a 5% extra rate]?
This is safe and will make good use of it.
 
Originally Posted By: mechtech2
What does that 1% consist of?

Most likely water. This is pretty pure grade lab stuff. Somebody paid a lot of money for it!
lol.gif


Does anybody know the pure octane rating of isopropyl? Tried google but couldn't find anything...
 
Originally Posted By: SecondMonkey
Originally Posted By: mechtech2
What does that 1% consist of?

Most likely water. This is pretty pure grade lab stuff. Somebody paid a lot of money for it!
lol.gif


Does anybody know the pure octane rating of isopropyl? Tried google but couldn't find anything...



There may be some "smell-bad(R)" or "taste-bad(R)" in that 1%.

An alcohol drag engine usually has between 20 to 1 and 22 to 1 compression.

There are different types of alcohol and they are not all the same. Some are more soluble in water and others are more soluble in oil. I think it depends on the amount of carbon atoms and where the OH is attached.
 
Last edited:
A lot of my saved info is lost due to computer problems.
But figure about 105 octane for the isopropyl.
Any water will be held in suspension and be harmless.
We use corrosive methanol in the wheelstander.
Low compression with high valve overlap, but a lot of blower overdrive!
 
Could the cleaning have been from the water? If it was a 50/50 mix of gasoline and isopropyl, and the isopropyl was 91% alcohol and 9% water, you were running 4.5% water in your mix.

On a side not, while water may not TECHNICALLY raise octane, I think it reduces the need.
 
Originally Posted By: n8wvi
Could the cleaning have been from the water? If it was a 50/50 mix of gasoline and isopropyl, and the isopropyl was 91% alcohol and 9% water, you were running 4.5% water in your mix.

I don't know, I was thinking about that. It sure was amazing to see though, I wish I would have taken pics. Maybe this spring I'll try it again under more controled conditions to see what happens. :) The extra high temp of the lawnmower engine might have something to do with it too, vs under 200 for a car engine.
 
Status
Not open for further replies.
Back
Top