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koko · Guest

If you do not own a E85 vehicle can you mix the tank of fuel with regular unleaded and still run? What would be the mixer if so?
thanks
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specialgreen · Posted: Tue Apr 12, 2005 10:12 am Post subject:

Fuel-injected cars (even non-FFV cars) can cope with a small amount of ethanol in the gas. For example, in Brazil, if you buy "gasoline", what you get is 80% gasoline, 20% ethanol (which is sometimes calle E-20). Many cars are imported into Brazil from world markets, and burn the 20% ethanol with zero modification. Minnesota governor Tim Pawlenty has proposed that all gas sold in the state have 20% ethanol by 2012. Currently, most gas sold in Minnesota is 10% ethanol (E-10).

If you want to try "E-20" in your non-FFV car today, you can mix 1 gallon of E-85 and 7 gallons of regular unleaded (10% ethanol) to get something about 19.4% ethanol:

hotrod · Joined: 19 Apr 2005 Posts: 872 Location: Colorado

This is my first post over here --- thanks for putting up an E85 forum to share info on!!

It of course depends on which particular car you have, but the general answer is yes for modern OBDII cars.

I have a Subaru WRX (2002 model) That I have been running on high ethanol blends of E85 and pump premium or race gas for nearly 2 years now.

On my car, with no modification, it will run up to about 33% E85 by volume with no problems at all. In fact a high performance turbocharged car like the WRX simply LOVE's E85.

If you go over 33% E85 by volume on (this) OBDII car it will throw a CEL (check engine light) and the code it throws is a "too lean" code. This is because as the ECU adapts to the E85 mixture in the tank, it gradually pushes the long term fuel trims to max rich. When it has done that for a period of time it assumes something is broken and throws the CEL. The car still runs just fine. You can turn the CEL off by putting a couple of gallons of gasoline in the tank and driving through a couple driving cycles and the light will clear.

After nearly a year of experimenting with the E85 in blends near 33% I modified the car by increasing the size of the fuel injectors, from the stock 420 cc/min injectors to 550 cc/min injectors used in the japanese versions of the WRX. This 31% increase in injector size allows me to run 100% E85 if I like with no problems.

These injectors are still a bit too small as I hit very high injector duty cycles at engine speeds above about 5500 rpm but it is not a problem that the mixture leans out because I am also running a water injection system in the summer time.

By the way, my car is the fastest Subaru WRX on the stock turbocharger at high altitude, running these E85 fuel blends. My best time on the stock turbo was a 13.239 @ 102.85 (this is at an altitude of 5800 ft) I am the only stock turbo WRX to have a trap speed over 100 mph at this altitude (next best is in the mid 99 mph range). I have lightened the cars a few hundred pounds but the E85 is responsible for a large fraction of this performance level.

My 13.239 corrects by NHRA correction factors to approximately a 12.84 @ 105.9 at sea level.

Try it you'll like it!!

Larry

specialgreen · Posted: Tue Apr 19, 2005 8:52 pm Post subject: Re: Probably yes

hotrod · Joined: 19 Apr 2005 Posts: 872 Location: Colorado

I didn't bother to inform the ECU that the injectors were bigger so it was fat dumb and happy on the 100% E85. I did have some minor issues if I went below about 50% E85 now, as the transition from closed loop to open loop fueling was a pretty big jump in mixture. I have a reflashed ECU in the works that I will be able to "tweak" the injector and mixture settings to my hearts content. I will also be installing an adjustable fuel pressure regulator so I can make these 550 cc/min injectors act like 600 cc/min injectors.

Yes my normal Pump premium here in the Denver area is required to be 10% ethanol during the winter months and I believe they drop it to about 5% or so in the summer --- ethanol is now a cost effective way to get octane and a cool burning fuel which makes the cooling system happy in hot weather.

There are lots of ways to "spoof" the ECU into giving you what you need, ranging from simple mods like you mentioned, up through increasing fuel pressure at the fuel rail to electronic add on / piggyback systems ($400 - $1000) to full blown stand alone ECU's which go for between $1000 - $1600 for the joe consumer models. The simple spoofs are pretty make and model specific as your faking out the ECU by cooking one or more of the sensor inputs.

In very cold weather ( <20 deg F) I run about 75% E85 to improve cold weather starting and make engine warmup quicker.

The modern OBDII ECU's will bring in the fuel trims pretty quickly. When I first did my tests with splash blending E85 at 30% or so I would after driving on normal or high octane gasoline, throw a 30% mix of E85 in the tank and just drive easily for about 5 miles and you could feel the ECU bring the mixture in to where it needed to be. As engine torque ( especially mid range part throttle torque) would improve very noticably in a matter of 10 minutes of driving. Based on my experiments with pushing the ECU far enough to throw a "too lean" CEL it makes most of its correction in the first 20 miles of driveing, then just tweaks the long term trims over the first 2-3 driving cycles after a major fuel change like that.

In a turbocharged car it is pretty easy, you just turn the boost down for a few miles than you can flog it hard with no worries.

Larry

excelguru · Joined: 21 Apr 2005 Posts: 1 Location: South Carolina

What if I have carbs? Here are my stats, if they matter:

• 10:1 compression
• Usually use 98 Octane
• Have used 100 Octane on occasion and it runs oh-so-nice
• Dual 600-CFM carbs
• Aluminum heads
• Timing at roughly 11° BTDC

Would there be any performance benefit if I mixed E-85 with the high-Octane fuel that I normally use? Would there be any harm?
_________________
Keith

Guest · Posted: Thu Apr 21, 2005 5:25 pm Post subject:

If the engine runs fine on 98, then the "improvements" with E-85 will be limited. I have been running E-85 in a carbureted motorcycle for 2 years now. It does clean-out varnish from your float bowls and jets Razz

.

The real improvements come since you could add domed pistons, maybe shave the head and raise compression to at-least 13:1. Of course, then you're stuck with either E-85 or race gas.

As far as harm, you'd want to add a fuel filter right before the carbs, and keep an eye on it. The ethanol may clean a whole lot of crud out of your tank. Also, if it starts to dissolve any hoses, you can see that in the fuel filter.

If your fuel tank has been brazed with lead-based solder, 85% ethanol can wash that away over time... not usually a problem unless the tank was repaired a loooong time ago.

Nothing much, really. But be aware that you'll have to adjust the jets.

Guest · Posted: Thu Apr 21, 2005 10:45 pm Post subject: changes for E-85

The answer depends a bit on how close your gasoline tune is to the edge.

In a generic sense you will need to richen the mixture about 27% - 35% to get the same tune on 100% E-85 that you have on gasoline. My understanding is that for most folks , this requires a about 2 steps in jet size to get in the ball park. Some folks need to change the needle valve inlet size and accelerator pump settings, and idle air bleed settings a bit as well.

The E-85 will have more octane than your 100 octane gasoline, plus due to its cooler burn you may be able to run slightly higher compression ratio or more ignition advance than you can get away with on gasoline. The proper ignition timing for E-85 is very similar to gasoline but if your normal gasoline tune is running a slightly retarded ignition timing to avoid knock, you will probably be able to run more advance with the E85.

If you mix just a little E-85 with your gasoline as an extender you will in effect lean out your tune, due to the presence of the alcohol. That may be a good thing, so if you want to work up to it a little at a time, you can probably add a little with no tuning changes. The alcohol has a higher evaporative cooling effect than gasoline so even a small addition will lower your intake air temps in the manifold and may give you a performance increase due to both an increase in the engines volumetric effeciency, and the cooler intake air temps (ignoring the octane) this may move you farther away from your knock limit. The alcohol may also improve the effeciency of the combustion process enough to give you more torque even with moderate changes.

If your current gasoline tune is a bit on the rich side the E-85 will both lean things out a bit and give you more power.

If your max power rich fuel air ratio for gasoline is 12.5:1 the same tune on E85 would require a fuel air mix of about 9:1

If you choose to work your way up with small addtions, Just go slowly and watch for signs of too lean combustion ( high EGT's) and such.

Larry