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jesse.rizzo 01-26-2008 02:48 PM

convert gas engine to run on ethanol
I was curious if it would be possible or practical to convert a car designed to run on gasoline to run on E85. From what I understand, the main problem with running E85 in a car not designed for it is that the ethanol is corrosive. After a while it would eat up the fuel lines and pump. So those would need to be stronger, but what else? Would this require a stronger fuel tank and injectors. Perhaps even something internal to the engine?

Also, where I live (kansas city) E85 is about 50 cents more than regular unleaded. In another city (columbia, MO if you must know) I've seen it at 50 cents less than regular. What's the deal with that.

Gone4 01-26-2008 03:57 PM

E85 runs at an octane of 100-105 generally. Your car needs to be modified for a higher compression ratio to suck every bit of energy out of the E85. If you leave it at a normal compression ratio you will be losing some efficiency. Flex fuel vehicles are designed at the lower compression ratios for gasoline so they do not run E85 under ideal situations.

Someone else can probably give more practical details on modifications required, but one of the problems is E85 is acidic and electrically conductive. This means you need to remove any bare aluminum, magnesium, and rubber. This means you need to put in stainless steels tanks and fuel lines, sometimes lined with plastic. Also some motor oils are slightly base to eliminate the acidity of E85 and reduce wear and corrosion.

bennelson 01-26-2008 04:04 PM

A new gas station opened up just a few months ago a few miles from my house.

It has the only E85 pump I have ever seen. I looked close at the pump to compare numbers. It costs about 50 cents a gallon less than regular unleaded.

That appears to be mostly because it is taxed very different than the standard fuels - you guessed it, by about 50 cents!

I have also heard that there is less fuel efficiency with E85 than gasoline, so you really aren't saving on cost per mile.

Also, I am in the Midwest, which is the Middle East of Ethanol, cost in other parts of the continent will vary.

Gone4 01-26-2008 05:19 PM


Originally Posted by bennelson (Post 7048)
I have also heard that there is less fuel efficiency with E85 than gasoline, so you really aren't saving on cost per mile.

We've done fuel testing on E85 at my university on a combined fuels research engine and this only held true if we kept the compression ratio for gasoline (pretty low). Once we increased compression ratios we immediately saw better efficiencies out of the fuel. We also did some testing with the timing and got some improvements out of tweaking that, moving it slightly further from top dead center.

cbergeron 01-27-2008 09:21 PM

Can you destroy a gasoline _engine_ by running E85 in it? I know it can corrode the fuel lines on older cars (pre-1990), but I've heard someone say it will cause the engine to seize up because of the higher octane.

Ethanol also burns much cooler than Gasoline, so it's better for your engine in the long run.


Frank Lee 01-27-2008 10:14 PM

No_damage_i'm_aware_of- been running it for years.

Lazarus 01-27-2008 11:53 PM

I played around with varying mixtures of Ethanol and did not take a big hit in FE until I got above E50. Up to that point I was seeing about a 10% decrease in FE. So If E85 is really cheap just blend a mixture until it get to that point where the FE starts dropping beyond your break even point.

Frank Lee 01-28-2008 12:05 AM

Lazarus: I have had similar experience with E85; not at all like those who project mpg losses based on BTU calculations. No doubt, they've never even tried it.

I will say, even above "E50" I didn't see more than about a 15% loss. The main caveat I'd throw out there is to expect some cold start and driveability issues if you go above E50 in below zero F weather.

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