E85 as a high-octane performance fuel
 

This past weekend was the Car Craft Nationals at the Minnesota State Fairgrounds. Among the many displays and events is the Dyno Competition. The top competitors are all running E85 in turbocharged or supercharged cars. The street-driven winner this year put down over 2,500 horsepower to the rear wheels. Many were over 1,500 hp. This is on readily available pump gasoline here in Minnesota. E85 is at most gas stations here. It's the cheapest 103-110 octane fuel you can buy.

Along those lines, I also spoke to a guy who owns a new 2014 Chevrolet Silverado with the 5.3L. He has been running E85 when towing, for the performance benefit.

The new GM Gen V motors now have direct injection, and they've upped the compression ratios accordingly. So the 5.3L V8 (L83) makes 355 hp and 383 lb-ft on regular 87 octane unleaded. But when running E85, GM has tuned the motor to make use of the higher octane, running more spark advance, more cam advance, and more fuel-events per stroke. The result is 380 hp and 416 lb-ft. That's an increase of 25 hp and 33 lb-ft torque with no other changes than the fuel. Run E85 when you need the extra power, run regular unleaded when you don't.

This gets me thinking of other modern direct-injected variable-timed motors and how they may benefit from this same "power adder". Especially force-fed motors like Ford's EcoBoost family. If Ford would tune the 3.5L EcoBoost in the F150 for similar gains it would yield 391 hp and 456 lb-ft (an increase of nearly 30hp and more than 35 lb-ft).

GM doesn't allow the pickup's 6.2L to run E85..... if it did, it would turn 450 hp and 500 lb-ft if it had the same impact as in the 5.3L.

Anyway, it was just interesting to me. A cheap power adder that you can run only when you want to. And many people don't know it.

I ran a couple tanks through my '12 Yukon 6.2.

Ran great - better than the 87 10% that I normally use.

Lost about 2-3 mpg.

It varies vehicle to vehicle, but 30-40% loss in fuel economy is typical.

http://forums.pelicanparts.com/uploa...1406151462.jpg


If you're doing it for the cost benefit, you need to do the math. If it's not 40% cheaper, then it won't make sense. Right now E85 would need to be under $2.00 a gallon (gas is $3.39 here). Not happening.

If you're doing it for performance, towing, or if you're having knock/ping problems, then the economics aren't the only piece to the puzzle.

It was getting pretty popular to update and re-tune certain sportbikes for E85 as I was getting out of the scene (only a couple years ago now). Many had really impressive NA power figures (lots of compression and revs can make use of the octane), but made the bikes almost unusable for street riding from diminished fuel economy/range. On 93 octane my ZX10 only had a range of 110 miles (plus or minus 10). Removing 40% of that meant I couldn't make it to the next nearest city for fuel (and E85 isn't as available here even now, years later).

E85 also has an extra oxygen atom allowing you to pump more fuel and still be able to burn it all.

my work truck. i can get 385+ miles from gas before i get nervous. with E85, just shy of 300.

feels the same tho.

Any opinion/data on running E85 in old, higher compression (9.5 - 10:1) engines? I don't care about fuel mileage, I just don't want to damage my engine.

That's not high compression. You would be better off with gasoline.

For reference, Mazda's new inline 4 has a 14:1 compression ratio and runs on pump gasoline. It is not turbocharged though. I imagine it would really wake up with E85.

MAZDA: SKYACTIV-G | ENGINE | SKYACTIV TECHNOLOGY

it works on over boosted turbo's very well
also allows adding a turbo to a mid-high compression motor

Ah the good old days of 6 mpg.

Stoichiometric ratio for gasoline is 14.7 to one.
IOW, 14.7 pounds of air for every pound of fuel used.

Shoich ratio for E85 is 9.8526
That means you have to dump in a helluva lot more fuel per cubic inch displacement. Turbo or supercharge and that radically increases the need for extra fuel.


Ethanol resists autoignition and deiseling so you can run a higher effective compression ratio. That increases torque which increases horsepower.
But you gotta dump in as whole lot more fuel to do it.


a 20% increase in power isn't very economical if you have to burn twice the volume of fuel to get it.

wait what?

E85 is great, because really, we need more fuel choices, and less standardization, at the gas station. E-10, in three flavors, and Diesel aren't enough choice. May as well throw in E85, CNG, hydrogen, (shade-grown fair-trade) bio-diesel and electric too. -hey, that Tesla 3 cars in front of you will be done in 30min's.

Seriously, engineers have understood these fuels for many decades, (^Sam) but when the people and politicians don't... this is what we get; a bunch of politically motivated technology push.

What a waste of time. But at least the corn lobby is happy.

and the manufacturers of replacement fuel system parts....

Please note that I avoided all of the political components of this on purpose, even the cost pieces.

If it can make more power in YOUR existing vehicle, and the fuel is already available at your pump, then it might be a nice consideration.

It also tends too cool the combustion chamber when injected batter than gasoline.

Perhaps that was poorly worded. Ethanol is an oxygenate and therefore your car will run lean unless you inject more. A chemist would be a better person to explain. Sort of like using NOS, you have to inject more gasoline because of the extra oxygen. Sort of.

what you are saying is 380hp is just not enough, and that for the simple extra hassle of a flex-fuel E85 system, added infrastructure, and many more trips to the gas station we can go from 380hp to 416. ...yeah, Feel the difference. ...or is that difference canceled out by the extra weight of fuel carried around? :-/

"Any opinion/data on running E85 in old, higher compression (9.5 - 10:1) engines? I don't care about fuel mileage, I just don't want to damage my engine."


10:1 is high compression for an engine without knock sensors and electronically controlled spark timing. Spark timing is mechanically controlled by the speed of the engine, period.

Politics aside, ethanol sucks balls.

Politics included, it's a travesty.

It works really well in modern engines with modern combustion chambers, optimized port velocity. It is a serious tuning challenge with older designs like hemi or large chambers with domed pistons.