Will the rx8 run on then new E85 fuel...or ethanol....With gas prices going through the roof I was just looking to save a few bucks..Plus it is higher octane than pump 93...thanks..

 

Read the manual!!!

 

It won't that I know of. There are only a few E85 stations around depending on where you are at. With an aftermarket ecu, you can program the car to run on it. If you'd like to learn how to make your own E85 or ethanol, check out this website:

http://running_on_alcohol.tripod.com/

Here is a list of the cars that can run on it. It is very small:

http://www.eere.energy.gov/afdc/progs/dealers.cgi

 

The "big deal" with Ethanol, is that is is MUCH more agressive on the seals in the entire fuel system. O-rings and fuel pump seals are "attacked" by the alcohol, and injector innards and fuel line "quick release" plastic all can become more brittle after extended exposure to the high-conentration of ethanol.

From a Stoich standpoint, it isn't too different than gas Since it has MUCH more oxygen already in the fuel (Ethanol is used here in milwaukee at 10% just for that reason...), the mixture will "burn leaner" when the same quantity is injected into the combustion chamber. This works in a very similar way as "leaning out" an engine. E85 vehicles have an "ethanol concentration sensor" in the fuel line to determine how much fuel adjustment is needed under WOT and Open Loop conditions. Since closed loop conditions are primarily based off of exhaust emissions, the computer compensates for the slightly different fuel automatically.

Since the '8 runs pig rich as it is, and closed loop mode IS used as much as it is, I would assume it would "run" adequitely on the E85 fuel. I would only be worried about longevity of fuel delivery system.

 

After reading the site linked by the rotarygod, it appears that they believe all fuel systems today can handle ethanol at most concentrations.

So, it would appear that all you would need to do is get your fuel mappings right....

 

To run pure ethanol you have to be in the 10.0:1 afr range unfortunetly. Not sure what the stoich point would be of the E85 blend (sure its around somewhere).

 

Actually Ethanol isn't all that hard on the car. Methanol is very nasty stuff.

 

but it *is* harder than just gasolene.

I don't know how much we have to worry about the compression ratio.. there are several of the Flex Fuel vehicles on the road today that are no where near 10.0:1... and they run fine with E85. (Chrysler's 3.3L mini-vans, for instance...)

 

thanks for the info guys...

 

stoich is around 10.8 for E85 (several sources i've looked at now)

this seems to be a pretty good subie thread on the subject http://forums.nasioc.com/forums/show...=637920&page=2

 

I've dyno'd an early 90's GM 4 banger running only 20% ethanol and it lost about 5hp and began overheating since it was running way too lean... a more modern engine management system probably could cope a little better by changing fuel trims but I doubt it could withstand more then ~30% ethanol at max

The flex fuel cars on the road have programming to detect E85 and adjust the fuel maps for it

 

So...flex fuels are part gas and part ethanol or something else? Most of the stations I go to run I think 10% or 15% ethanol in the fuel. Should I be looking for stations that are pure gasoline? I hope I'm not going to start a debate similar to the synthetic vs. nonsynthetic. :D

 

"Flex fuel" cars are cars that come from factory made to handle either pure gasoline of E85 (which is gasoline thats 85% ethanol).

Most gasoline runs a recentage of ethanol now for emissions. 10-15% should not have any noticable maintenance issues and you ecu should be able to adjust the fuel maps to compensate for that amount.