|07-08-2005, 10:52 PM||#1|
Join Date: Jan 2002
Location: [email protected] @ 5800 ft on 13TVehicle:
2002 Impreza WRX
E85 fuel FAQ
Introduction to my experiment with E85 circa 2004
This is a summary of past posts from various forum discussions
I have been running a high ethanol fuel blend in my WRX for nearly 2 years now, with no problems traceable to the fuel. The car really likes the high alcohol blend, with an obvious improvement in performance comparable to high octane so called "race fuels".
The Stock WRX ECU can handle up to approximately 33% E-85, by volume before you get a check engine light for "too lean" due to the fuel trims being pushed to the max rich settings. Add just a bit of pump premium and the CEL will clear.
I recently shifted to STi 550 injectors without any special changes in the engine management. Due to the cars larger injectors the car now prefers a higher blend. I am now running about 95% E-85, but have run the car on blends as low as about 30% E-85 without any serious problems. At lower blends the car has some surging due to the over size injectors at higher throttle settings, but can be easily driven as a daily driver if you stay out of the >60% throttle position transition to open loop.
The one problem is that currently E-85 sites are a little difficult to find, but the more of it we use the more available it will become.
The folks backing E-85 production are pushing as hard as they can to get stations to make it available, but its a slow process. They need customers to start asking station owners if they plan on carrying it to motivate stations to add a pump/tank.
There are currently dozens of FFV's out there that are designed to run on the stuff if folks can find a place to buy it. Simple way to drastically reduce oil demand as well, and put money in our economy instead of some other countries coffers.
I currently drive 20 miles each way to get to the nearest E-85 stations, but it is still a good deal as I am paying $1.59.9 / gal for the E-85, vs about $2.05.9 / gal for premium. ( some E-85 vendors charge at a premium fuel rate of about $2.00/gal)
With the added octane of the E-85 you can actually splash blend it with mid grade gasoline with out problems.
When I suspect it will be difficult to locate E-85 from the pump I just make a point of topping off the tank before it drops below 3/4 full. This keeps the ethanol blend up to a high enough level to avoid any drivability issues with my oversize injectors.
Is the WRX warrantied to run on E85 ?
NO it is not, but my experience shows its not a major issue either.
I think it is important to note that they don't recommend greater than 10% ethanol, ie they warranty the car will run fine with up to 10% ethanol but greater than that your on your own. But they do not say you should avoid higher blends of ethanol and other tests have shown modern cars can run on upto about 30% blends with no problem.
They do specifically mention that methanol is not to be used over 5% concentration, and that is due to corrosion issues with methanol, which is Much Much more prone to corrosion than ethanol.
So far I have seen no "real" problems with the E-85. There are two minor CEL issues.
1 If your running over 35% on a stock ECU and fuel injectors you will push the fuel trims to full rich and get a "too lean" CEL.
(edit 10/02/2005 --- emission CEL has not re-appeared in quite a long time. I am beginning to suspect it was due to a loose vacuum hose resulting from the injector upgrade that got fixed as I was working on other things )
As mentioned above any "damage" should be easily remedied, ie replacing a hose, or some O rings, possibly changing to a different fuel pump. It is very difficult to predict long term corrosion, or materials compatibility so I've decided to bite the bullet and be the test dummy and see what if anything breaks.
Based on my tests, the short term conclusion is you can run concentrations of >10% fuel ethanol for periods in execess of 1 year with no detectable damage. We'll just have to see how things go in another year or so.
Hopefully this winter I'll get the time to pull the fuel pump and look over the interior of the fuel tank to see how its doing.
What is the history of large scale conversions to high ethanol fuels
When Brazil began making a wholesale conversion to high ethanol fuels back in the late 70's following the energy crisis, they made several studies on the ability of normal cars to run ethanol blends. They found that the cars of that period could run up to about 22% blends on the stock system with no problems, which is why they settled on a 20% blend as one of the fuels available. The issue was one of control authority of the ECU to compensate for the leaner mixture. Some could handle more than others. As I stated, it appears the stock ECU on the 2002 WRX is good up till about a 33% - 35% blend.
During the 70's and 80's when oxygenated fuels and "gasahol" first saw wide use here in the U.S. there WERE fuel component compatibility problems. My 1969 VW fuel lines really didn't like the ethanol and began to leak like a sieve, some carburetor needle valves softened, some carburetor floats would soak up the ethanol and get too heavy to function as a float. There were lots of problems with clogged fuel filters on cars that had been running on gasoline only for decades and had lots of varnish build up in the fuel system. The ethanol in gasohol was a very efficient fuel system cleaner and all that crud got carried to the fuel filters. Once the fuel filters were replaced those problems disappeared.
At that time All the auto manufactures moved to ethanol compatible fuel line components, ie. o rings, rubber hose etc. They warranty that they are good to 10% but my experience shows they are satisfactory to much higher concentrations. The VW showed its compatibility problem in a matter of months after we went to ethanol blended oxygenated fuel here in Denver. Engineers typically don't solve a compatibility problem by making the new component "sorta compatible" they change compounds to materials that are not effected by the chemical in question.
The Denver area has been using ethanol oxygenated fuels (ranging from 5% - 10%) concentration for over 30 years. Every modern car works just fine with these low ethanol blended fuels. Rubber hoses and O rings last for the life of the car.
The electrical conductivity issue is not significant in the case of ethanol. It is detectable with a dialectic constant tester. It DOES become a significant issue with methanol blends which is why methanol blended fuel is so aggressively corrosive. The main issue with methanol is it aggressively attacks certain metals like magnesium and zinc. One of the reasons everyone is looking at ethanol is the 30+ years of successful use of high ethanol fuel blends in Brazil and low ethanol blends here in the U.S. with essentially zero problems after they changed fuel line and O ring and seal materials in the fuel system.
Water 48 - 88
Keep in mind that absolutely pure water is a good enough insulator it is used to cool electronic components. It does not become an effective conductor until is dissolves minerals that act as charge carriers (electrolytes).
Will my O2 sensor work with E85 and high ethanol blends?
The O2 sensor is not an issue, all it cares about is if your at stoich combustion at low throttle settings, it doesn't much care how you get there, so no need to change it.
Air-fuel ration: http://en.wikipedia.org/wiki/Air-fuel_ratio
Oxygen Sensor: http://en.wikipedia.org/wiki/Oxygen_sensor
What about the evaporative emissions system in my car
The higher vapor pressure of ethanol gasoline blends is not ideal for the evaporative emissions system and the vapor recovery canister. For full emissions compliance these will need to be modified. Currently there are no kits available to upgrade this part of the emissions system.
As I mentioned above the only -- real -- problem so far is simply some nusince CELs.
"too lean" if your over 30%+ on the stock injectors
If your emissions test requires no CELs present, you simply need to go to a lower ethanol fuel blend for a while to allow that nuisance CEL to clear, and the dash warning light to go off.
what would be needed for a complete conversion kit to run 100% ethanol fuel
For full conversion to alcohol fuels the change list typically looks something like:
1. Go to an compatable fuel pump (walbro 255 l/h pumps seem to work well with E85)
2. Replace fuel lines with alcohol compatible lines. (not needed on WRX based on current experience)
3. Possibly replace filter (not needed on WRX based on current experience).
4. Replace injectors with large enough ones to feed proper fueling. (+30% flow over stock)
5. Replace injector/FPR o-rings with compatible o-rings... viton maybe? (not needed on WRX based on current experience)
6. Add a spark/flash suppressor to the fuel tank inlet tube. (does not appear to be a significant hazard based on current experimenter experience)
7. Ensure the fuel tank material is completely compatible with alcohol. (not needed on WRX based on current experience)
8. Reflash or other engine management option for ideal tune to use E85's capability (optional at low to moderate boost)
With ethanol on the WRX, you only need (according to my current experience base) is numbers 4, 8.
(edited to remove comments about emissions CEL which proved to be due to other causes and has never returned)
What about fuel system corrosion?
Corrosion does not appear to be an issue with modern OBDII cars. They are all certified by the manufactures to be safe to use on 10% ethanol fuel blends, and industry insiders say they are safe for much higher percentages. You don't install components that are "sorta safe" with a chemical, you put in a fuel hose etc. that is ethanol safe for concentrations well above what you expect to use. Not to mention that folks have been talking for years about raising the ethanol level to 20% or more.
Occasional use would be no problem at all based on my experience. I have never cut open the fuel filter (still have the OEM filter in place) I'll open it when I replace it. I want to put enough time on it to have conclusive evidence if there are problems.
(edit circa 2007 I cut open a fuel line and it looked like new, not changes or damage on stock rubber fuel lines in 2002 WRX)
The engine is not an issue with either, WI using a water alcohol mix or straight alcohol injection. In those systems alcohol and water are not used in significant quantity or for long duration. The Buick GN folks and lots of folks in the DSM crowd have done it for literally decades with no problems for the engine.
Many years ago there were studies that indicated engines that ran on alcohol ALONE as a fuel, had issues with lubrication and valve seat wear. Keep in mind, those studies were done a long time ago, when engine oils were much less sophisticated than they are now, and some engine manufactures in the 1940's,1950' and 1960's made stupid engineering decisions and did not use hard valve seat inserts like stellite in the cylinder heads. This resulted in valve seat recession problems if you did not have lead additives in the fuel to protect the valve seats.
What about oil contamination?
Modern lubricants, especially the synthetic oils are much much different than the oils used during those studies, and modern engines run at higher temperatures today which will quickly boil any traces of alcohol out of the oil.
In cold weather I run an 180 deg thermostat to assist quick warmup I have left it in during this past summer and so far the engine has no heating issues with the 180 thermostat on the E85 fuel.
(edit experience shows modern synthetic oils work very well with E85)
Is Ethanol less corrosive than Methanol?
Methanol is much more corrosive than ethanol. It attacks certain soft metals that are not much used in modern fuel systems. Years ago, the carburetors were made of un-anodized aluminum and if methanol fuel was used, you had major problems with electrolytic corrosion between the aluminum and copper components used in the fuel system, since they were in continous contact.
That sort of corrosion only occurs when you have a current path between the dissimilar metals AND, a conductive path through the fluid in the system.
In Brazil where they have run high ethanol fuels since 1939, they found that to convert older cars designed for gasoline, long before ethanol blends were common, needed several changes to convert the cars over. This led to changes in valve materials, piston rings choices, nickel plating of the fuel tanks etc.
Modern cars in the U.S. are designed for use with ethanol up to 10% concentration in the fuel. That has led to several changes in component materials over the last 30 years that the U.S. has used ethanol enhanced fuels. All modern fuel lines and such are designed with the expectation that some ethanol will be in the fuel.
My experiment is an intentional effort to push the envelope and see what happens. Over the last 2 years I have run high ethanol fuels ( normal pump fuel here in Colorado contains up to 10% ethanol anyway) for months at a time.
At mixtures below 33% by volume of alcohol ( about 39% E-85 by volume) I had absolutely no problems of any kind. At higher mixtures > 33% alcohol, I got a nuisance CEL for too lean which could be eliminated by added gasoline to the mix or as I have recently increased the injector size. (Increasing fuel pressure would also increase the effective size of the injectors).
The only issue with near 100% E-85, is the car starts a little harder in cold weather. When it gets very cold I drop the mixture to about 80% or so to solve that by adding about 2 gallons of gasoline to the tank of E-85.
I have done no oil analysis at this point, walbro 255l/h fuel pump and 550 injectors show no signs of problems to date.
(last updated 6/10/08)
Last edited by hotrod; 07-02-2008 at 04:11 AM.
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