Guzzling the E85

[Nick1994]

I decided to try E85 for the first time in my Flex Fuel ‘14 Grand Cherokee. Never making that mistake though, it gurgled it down! The last few tanks have been a lot more short trips, as I’ve saved longer drives for the Camry. The 2 with E85 were at 11.9 and 10.8 mpg.

I can get it for about a 10% savings now at $4.49 while regular is $5.03. But my fuel economy dropped about 21% from 14.4 to 11.3. Might not sound like a lot, but you could totally tell how bad it was only able to go about 250 miles on 23.3 gallons of gas.

However, it definitely had more power. I’m usually pessimistic with that kind of stuff, but it was a big difference.

Anyone else have similar experiences?

 

[MParr]

Explain how you get more power out of a lower BTU fuel.

 

[Oily Ed]

Higher octane rating allows advanced timing.

 

[Astro14]

You’re doing well with a 20% drop in MPG.

I would expect a 35% drop in MPG based on BTU.

My Flex fuel truck, on E85 sees a 15-20% drop in MPG. It likes the octane, but there is no getting around the lower energy density of ethanol.

Currently, E85 is $3.95. 87 is $4.45. No point in buying E85, it’s a higher cost/mile.

 

[slacktide_bitog]

The math would work better for cars that require premium, turbos, etc.

 

[vw7674]

Explain how you get more power out of a lower BTU fuel.

The fuel injection system flows more of the E85 per combustion cycle, hence the drop in mpg.
But the higher flow also unleashes more btus, + the cooling effect of the alcohol is greater. Absorbs heat.

 

[HeritageHighRoof]

1-ton GM van with 6.0 and 6L90 went from 16 mpg on E10 regular ($3.99) to 13 mpg on E85 ($2.69). Had better response and did not downshift as much on hills. The stations near me don’t have price spread wide enough to justify E85 most of the time.

 

[Cujet]

Note: It is possible to achieve excellent (diesel like) thermal efficiency on E-85. However, it does require a dedicated engine design.

Put more simply, the BTU input matches the output HP. MPG does not match the diesel, only the in-out relationship.

One of the keys to making an efficient E-85 engine is operating it with a BMEP over 200 PSI. Brake Mean Effective Pressure is a theoretical measure of average cylinder pressure. It is not a real number. BMEP is: the average (mean) pressure which, IF imposed on the pistons uniformly from the top to the bottom of each power stroke, would produce the measured (brake) power output.

Modern automotive engines are quite far from doing well on E-85.

 

[Wrenchturner44]

My Dart runs way better on E85. Mileage is 7 - 10% lower. I was told that you need to run a few tanks through to clean the combustion chambers and valves before you can compare mileage and power ratings, especially on cars that have been running 87 regular unleaded.

I sometimes mix E85 in 2003 Durango (been doing well over 10 years) and have had no issues with no more than 1/3 of tank being E85.

Lastly, it sure will clean up any marginally dirty injectors, so you will never need any kind of fuel additive for same.

 

[Nick1994]

Explain how you get more power out of a lower BTU fuel.

Not sure, but it was a night and day difference. Much more response and a nice power-band.

The Pentastar at 134k miles on this heavy 4x4 Jeep is a bit of a slug normally.

 

[High Performance Lubricants]

Note: It is possible to achieve excellent (diesel like) thermal efficiency on E-85. However, it does require a dedicated engine design.

Put more simply, the BTU input matches the output HP. MPG does not match the diesel, only the in-out relationship.

One of the keys to making an efficient E-85 engine is operating it with a BMEP over 200 PSI. Brake Mean Effective Pressure is a theoretical measure of average cylinder pressure. It is not a real number. BMEP is: the average (mean) pressure which, IF imposed on the pistons uniformly from the top to the bottom of each power stroke, would produce the measured (brake) power output.

Modern automotive engines are quite far from doing well on E-85.

This.

However E-85, if you have the power adder available is pretty awesome. Net +200 RWHP (809 RWHP total) on my twin turbo Coyote Mustang over 93 octane when switching to E-85. Other than the intercooler behind the grill one would never know. The downside to a 15 is they were not flex fuel. I had to put a stainless fuel system on the car. A 18 or 19 flexfuel with a 10 speed is a great candidate for Turbo, turbos, or Pro Charger. After putting this one together I would lean towards the Pro Charger. Much easier installation and no lag. Even with smaller turbos on the 15 it is still not as responsive as a Pro Charger.

 

[Skippy722]

Our Grand Caravan also feels peppier on E85, even my wife noticed… “What did you do to my van?!” lol! But like you, we went from 19-20mpg to 14-15.

 

[CharBaby]

Nice car and I love the wheels on that Stand!

 

[CharBaby]

Correction: On that STANG!

 

[Deleted member 89374]

This.

However E-85, if you have the power adder available is pretty awesome. Net +200 RWHP (809 RWHP total) on my twin turbo Coyote Mustang over 93 octane when switching to E-85. Other than the intercooler behind the grill one would never know. The downside to a 15 is they were not flex fuel. I had to put a stainless fuel system on the car. A 18 or 19 flexfuel with a 10 speed is a great candidate for Turbo, turbos, or Pro Charger. After putting this one together I would lean towards the Pro Charger. Much easier installation and no lag. Even with smaller turbos on the 15 it is still not as responsive as a Pro Charger.

View attachment 102453

What motor oil is this beauty running?

 

[Tman220]

I used to own a 2005 Sierra with the flex fuel L59 5.3. It was only 9.5:1 compression but I could still take advantage of E85 when towing. My mileage drop was in the 20% range as well but with much more power and gear holding ability.

The extra power came from the extra ignition advance you could get away with.
As an example, towing a trailer in OD at 60 mph monitoring timing advance, the advance with 87 octane would generally drop down to the 12-14 degree's advance just before calling for a downshift to 3rd

With the same trailer, with the same load, with similar temps the engine would be able to maintain 28-30 degrees with e85 before calling for a downshift from 4th to 3rd at 60mph

This is how you only drop 20% fuel efficiency with a fuel which contains 30% less BTU's. The engine was better able to utilize the BTU's in E85 compared to 87

 

[tnt_motorsports]

@Nick1994 I experimented with E85 in my wife's 2014 T&C w/ a 3.6L a few years back. It was more than 10% cheaper so I thought heck why not... I experienced exactly what you experienced, so I have not used it since. I will however us 88 (E15) here in Iowa if there is a significant price difference from 87 (E10). The mileage drop from E10 is much less noticeable with E15 that E85...

just my $0.02

 

[High Performance Lubricants]

What motor oil is this beauty running?

I run 5w30 in this car.

 

[Deleted member 89374]

I run 5w30 in this car.

I mean, which 5W-30 specifically?

 

[High Performance Lubricants]

It is our BAS 5w30. It is a streetable version of a race oil that was born out of our Pro Stock experience.

I believe RDY4WAR has run the same oil out to 9,000 miles if memory serves correct in one of his vehicles.