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huxrules 10-06-2012 02:50 PM

Car seems faster with ethanol
I recently tried some E85 in my car. Just because I can. The focus now seems faster which I didn't think was possible with ethanol. Is the engine capable of changing the timing due to ethanol's higher octane? The milage has gone down but if I can easily get more performance I'll do it. Anyone notice a change with ethanol?

lyonsroar 10-06-2012 02:54 PM

GMconvert 10-06-2012 03:45 PM

FI guys do quite well with E85, at least the S/C and turbo Buick crowd does. It burns at a lower temperature than gasoline and some have compared it to a small intercooler. They have also upgraded all fuel system components (pump/lines/injectors if needed) and have tuned for the different AFR of ethanol.

Putting ethanol in any gas engine that's not tuned or designed for it usually results in lower mileage and less power. When E85 was whole dollars cheaper than gas, it made sense because the cost offset made up for using more E85 for the same amount of miles that gas would give you. Now that it's within a few coins, it's not worth it.

And yes, all modern cars will alter timing based on air temp, fuel octane, etc. to a certain extent, but there are still parameters outside of which it can't extend. Unless you specifically tune for it, it's best to use what the manufacturer calls for. On my '00 Blazer, I actually get more miles out of 89 than 87 - enough where it's actually cheaper to use 89. My S/C Regal required 93 so that's what it got. There was definitely a drop in power if you used anything lower because the PCM pulled timing to safeguard the engine from the lower octane. The '10 Focus sees no advantage in mileage (which is why I bought the car) for anything above 87 over the course of dozens of tanks of each grade, so it gets 87.

CLIFFor Sale: In non-forced induction cars, ethanol and ethanol blends generally result in less mileage but not necessarily better performance, unless you're specifically tuned for it.

I'd wager that the new ST would do better on E85 than gas once it's tuned due to the turbo.

whynotthinkwhynot 10-06-2012 04:36 PM

The fuel system is not designed for it. I know people who have tried it and had problems. DiscipleRocks is one FF who has been running E85 for a long time IIRC.

Newer engine software might contain an algorithm to advance spark to the point of knock, and then back off X deg. It might test for this regularly to keep the most advance. It would be nice to know for sure, but that would explain your power bonus. Of course, the new Focus has compression ratios closer to what works best for E85 anyway.

I personally would like to see more interest in isobutanol myself. It reduces hydrocarbons more than E does, and doesn't cause fuel separation. Maybe in the next 10 years or so. Right now, it's an emerging tech, but E plants could be converted, and we wouldn't be 100% reliant on corn for fuel additives.

mjd4277 10-06-2012 05:51 PM


Originally Posted by whynotthinkwhynot (Post 4390764)
The fuel system is not designed for it. I know people who have tried it and had problems.

Agreed. It's clearly marked on the gas cap of my 2010 that gasoline with E80-E85 is a no-no.

GreySkorpion 10-06-2012 09:57 PM

Add stickers, that will make it faster.

StingRay 10-07-2012 03:33 AM

I'm not sure on the 2012's but my '13 is flex fuel capable, so yes the fuel system is designed for it. The new computer system on the MK3 is supposed to be able to adapt to any amount of ethanol content and change the tune to achieve optimal AFRs, or at least that's what I've read. Technically the car could add more timing and therefore make a tad bit more power, but I'd have to see a dyno sheet that proves it's making more power because I wouldn't think the factory ECU has performance in mind when it changes the tune.

iminhell 10-07-2012 05:09 AM

Hearsay and conjecture.

The fuel system wasn't designed specifically for Ethanol. That does not mean it's not compatible with it.
People will say 'you'll run lean and blow up your engine'. Though the possibility is there, the odds are low. As far as the fueling is concerned, nothing in the system knows what type of fuel you're using. All it knows is that it's shooting for ~0.5v average during closed loop and a preset Short Term Fuel Trim during open loop. Providing the injectors can supply enough fuel, these presets will be hit even on E-85.
The Flex Fuel vehicles have an added Ethanol content sensor that measures the specific gravity of the fuel. Ignition timing is adjusted according to Ethanol content.

Yes more power can be made on Ethanol than pump gas. But it is also correct to say that the majority of the time this will not be the case unless you can adjust the ignition timing to take advantage of the added Octane.

Best advise I can offer is that if you wish to try it, please do so safely and know the risks going in. It would also be a good idea to be able to view live data; that way you have a little warning if something isn't going well.

huxrules 10-07-2012 11:12 AM

The focus in question is a 2012 and is a flex fuel version.

whynotthinkwhynot 10-07-2012 11:23 AM


Originally Posted by huxrules (Post 4391691)
The focus in question is a 2012 and is a flex fuel version.

Then it would be nice to know power output, fuel consumption, and $/mile comparison. It would be nice to know if it works great if you have E85 readily available. In my market, it's not so easy to find.

There have been some advances in fuels and energy in the past 4 years or so that we're going to see the benefit from in a few years. So much of alternative energy options are in their toddler stages- slightly past infancy. I'm curious to see what happens in the next few months. The battle between fossil fuel advocates and future tech rages on.

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