This is just an idea I'm tossing around in my head, since I havent assembled my 390 yet. With the price of gas at $2.00 / gallon here, going up, and no end in sight, one of those crazy ideas has come into my head. Hear me out.

Ethanol has a higher octane rating than gasoline. Like 106 or something. I was thinking, that I could run high compression and extract the most efficiency out of it and get better mileage, possibly equivalent to gasoline.

Here's how. According to Desktop Dyno, with 75cc heads (72cc heads with 3cc valve pockets), .020" thick head gaskets, and the piston down in the bore .016", I'd wind up with a 10.74:1 compression ratio. What I would do, is sell the 941 cam I have now, and use a 901. This will build a LOT of compression, and fully utilize the ethanol.

There's a site on the internet (yeah I know...) that sells plans to build a still for $30. The license to make it legal is $15. In addition, there's a tax credit of like $.50 / gallon you can write off you income taxes. Seems like to a good deal to me.

Any thoughts?

 

what is the btu of ethanol? that will determine fuel economy. can you mix ethanol with methanol or gasoline? also give the link for the still......

 

Sure. Here it is.

There's more than just BTU's that determine fuel efficiency. Compression ratio is one of the big ones. Even then, according to that site, it only costs $0.80 - $1.20 to make it, and then with the tax credit, you'd be hard pressed not to come out ahead.

Edit: Go to the "Ethanol fuel challenge" link on that site for more information regarding fuel efficiency.

 

Can you mix them?
If the alcohol is dry (I forget the exact requirement), then you can. But if it has significant water content then they won't mix. In fact, if you'd ever want to remove the ethanol from gasohol, just add water. You'll wind up with gasoline floating on top and a water/ethanol mixture on the bottom. You really wouldn't want to do that. Just for curiousity's sake.

It's true that compression ratio is a big part of fuel economy (and power), but I doubt it would be enough to offset the lower energy content.

I think it would be really fun. Really, really fun. And for that reason alone I'd strongly encourage anyone to do it. But unless you have a free source of corn and a free source of wood to fire the still, it wouldn't save you any money.

Even though gas is more expensive than it's been in recent years, it's still one of the best bargains around for what it does for you. Just thing about it. It can carry a 5000 lb. truck ten miles for only two dollars. Sure beats pushing it. ;-)

 

I do not think you will recover enough to make up the much lower MPG with ethanol.

 

Concerning fuel efficiency, here's a quote from the site that I linked:

FUEL EFFICIENCY: In 1998, eight vehicles had better fuel efficiency than the stock Malibu. Vehicles achieved the same range on one tank of ethanol as the stock Malibu achieved on one tank of gasoline. This success continued in 1999 when 11 teams achieved better fuel efficiencies than the gasoline Silverado. The winning team, University of Illinois-Chicago, demonstrated a greater-than-10% increase in fuel efficiency.

Apparently, it can achieve the same fuel efficiency as gasoline. And these weren't high compression engines; they were merely retrofitted.

 

That is probably true. BUT...
I'll bet they were measuring efficiency as a percent. Most spark ignition engines (gasoline, alcohol, natural gas, propane, whatever) are around 20-30% efficient. Diesels can go up to 40% (or higher in special cases). But, since ethanol has lower BTUs per gallon, the MPG is still significantly lower.

So you could have a higher efficiency, but a lower MPG, since the energy content of ethanol per gallon is lower.

I still think someone should do this, though. It's a cool thing to do.

And when you can perfectly control your fueling system with the push of your laptop keyboard, it would be totally excellent.

 

Like I can with my new fuel injection system.

 

Gasoline: 124,800 BTU/Gallon
Ethanol: 76,500 BTU/Gallon
Methanol: 64,500 BTU/Gallon

I got these from an internet source.
I'll try to confirm with engine text books tomorrow.

 

Bingo!
That would be totally cool.

 

with fuel injection couldn't you just turn up the pressure? espessially if you could get the water out and use a 50/50 mix of gas and ethanol, that should just about cut gas prices in half.

 

With my Commander 950 system, I can modify basically everything. So it's just a simple matter of tuning the base map for it. No need to turn up the pressure.

I was kind of waiting for Scouder to come in with something about dynamic compression ratio.

 

Wouldn't the performance be better at 14:1?? Not to mention sound pretty mean aswell?

 

That's kinda what I was thinking, but then I'd need to buy new parts. As it is, I can use the .020" thick fel-pro head gaskets, some D2TE-AA heads I've got out in the garage, and the TRW L2291F30 pistons to get about 11.4:1 compression. Even with the 941 cam, I think this would be plenty for the ethanol to work good. Besides, I dont want to get it so high that it pings with the ethanol! Then I'd have to pull it and lower the compression.

If there was a way to raise compression more, I'd probably do it. As it is, my choices are to get the heads milled, domed pistons, or a smaller head gasket. The second and third ones are a no go as far as I'm concerned, as my deck clearance will already be .016", and the gasket makes the head quench area .028". Any lower and on high revs the piston has a chance of smacking the head. Not good. The other one, domed pistons, are too rich for my wallet. I've already got good TRW's (that I got for free with the truck from my brother I might add).

I calculated the dynamic compression ratio, it's 8.57 with the 941 cam.

 

Rusty, I like your idea. I'm trying to save up a few bucks and do one myself. I also wonder if I should just try to use the over 11 to 1 421 that I already have. Anyway, I think you'll be able to get the same or better mpg with the ethanol that you do with gasoline. As you have found searching the net, its already been done. Too much has been made, IMO, of the differance in btus. The btu test is done by measuring how much fuel it takes to boil a gallon of water. But we aren't boiling water ! Because the alcohol flame is cooler ( compared to gasoline ) and slower burning, more of the heat from the burn is able to be utilized. Ethanol is the fuel that Mr Ford intended. It burns cleanly and is farm producable. The one and only reason we don't all run on ethanol currently is because GM, in collusion with Rockafellers Standard Oil, flooded the fuel market with cheap ( and toxic ! ) petroleum fuel with tetraethyl lead mixed in. They sold enough of it that the ethanol industry was crushed. It was all done to make profits for the oil industry. They knew it was toxic and it was even killing the workers who brewed up the fuel. But it made profits beyond obsenity for the oil guys. ( getting down off soapbox now...) If you want some more compression, mill the heads .030. Leave the intake manifold unmolested and mill the intake side of the heads the same .030. And while you're building that still, look around for a station that sells E85. It is a mixture of 85% ethanol and 15% gasoline. Iowa should have some of those. What city are you in ? DF