E85 in the Jeep

[rslifkin]

The Jeep needed gas anyway today, so I figured I'd throw some E85 in the tank just for kicks, as it was about $0.25/gal cheaper than the 93 octane it normally gets.

I ended up putting in 10 gallons, so my tank currently contains about 43% E85, 57% 93 octane gas (E10). This should yield about 42% ethanol in the tank overall, if my math is correct.

So far, I've driven about 25 miles, and it seems to be running great. I gave it a few miles of varied, gentle driving to let the fuel trims adjust before I wailed on it. After a bit of adjusting, my throttle response seems a little crisper, and it sounds a tiny bit different. Overall power at full throttle seems pretty much unchanged, and there's no dead spots in the powerband or anything, not a hint of pinging or any other signs of a problem.

Depending on how it does in terms of gas mileage on this tank, I might just fill it up with E85 the next time around, which would probably put me somewhere around 75 - 80% ethanol.

 

[dakotasport94]

what year and engine is in the jeep?? is it E85 compilable??

 

[Zaedock]

I wouldn't run E85 in your 360. Besides not being made for it, any money savings will be canceled out by poorer mileage.

A few of my friends and I accidently filled with E85 on the way to Moab a couple years ago. I was getting about 12 in my Ford towing my Jeep and went down to about 9. It seemed to run OK though.

 

[dakotasport94]

Zaedock: I guess you know the answer to my question...thanks...LOL

 

[rslifkin]

It's the original 98 5.9 Magnum engine in the Jeep. However, while it's not designed for E85, the injectors are new and about 10% larger than stock, and the o-rings are new, and it's got a good bit of other engine work done (top end has 11k miles on it). The rest of the fuel system is new enough that the materials should all be alcohol resistant, so there's no reason it should have an issue with it.

And yeah, the mileage will probably take a pretty good hit, assuming the computer actually richens it up enough to compensate fully for the E85. I did it mostly out of curiosity about the mileage. Fortunately, the tune on it currently is pretty agressive (not super-rich, and pretty advanced timing, it's on the verge of pinging at times on 93). It's right around 9.5:1 compression currently, which is low for E85, but hopefully the rest of the systems lead to it not getting horrible mileage.

Unless it turns in better than expected mileage, I'm not planning to continue running E85 in it, as it's only about 5 - 6% cheaper than 93 octane. The improvement in throttle response (confirmed by a friend) is nice though, and I'm also not sure why I'm seeing that (running a bit lean maybe?), as I didn't change anything in the tune.

 

[exranger06]

Did you get E85 in Rochester? Last time I checked E85 isn't available anywhere in CT. That may have changed though.

 

[rslifkin]

Yeah, I'm up in Rochester at the moment, and I'm pretty sure you're correct on it not being available in CT. If I wanted / needed some while at home, I'd have to drive the 25 minutes down to Rye, NY to get it. Paid $3.89 for E85, compared to $4.09 for 93. If it doesn't kill the mileage too badly, it would be cheaper to run a 60/40 mix of 87 and E85, as those are both about the same price currently, and about $0.20 less than 93.

Based on how many miles I got before the gas gauge began to drop off the top peg, I'm figuring on a 10 - 15% mileage loss, which would make it more expensive to run E85 than E10.

If I decide to supercharge the Jeep at some point (considering putting a 5 speed in this summer, after that, I might supercharge it), then I'd make sure my injectors are big enough, etc, that I can run E85 or E10 interchangeably with just a boost pressure change.