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Does my engine have to be in perfect condition?  My vehicle has a lot of miles on it; is it too worn out?

A successful ethanol conversion should start with a car that has been properly maintained and is in good working order.  High mileage is generally not a barrier so long as the car runs well.  We have customers who have converted high mileage cars with well over 200K miles and their vehicle runs great on ethanol.  But if your car is burning a lot of oil, has poor compression, runs poorly or is hard to start, those issues need to be addressed before attempting conversion. 

I have an older car with high mileage.  It runs well, but what things should I check to make sure they are OK?

Rubber – If your vehicle is old enough, it may have rubber components in the fuel system.  We have found that if your vehicle was manufactured after 1990, it is probably free of rubber in the fuel system.  If you are converting an older vehicle, you will likely need to replace the fuel line and the fuel pump with modern components.  If your vehicle is newer than 1990 and it looks like it has a rubber fuel line, it is most likely made from neoprene.  Neoprene looks like rubber but it is not reactive to ethanol and is fine.

Fuel Pump – The fuel pump needs to be delivering adequate pressure and flow.  Stock OEM fuel pumps generally deliver plenty of fuel for your engine even with it running E85.  If your vehicle can currently run well at full throttle, your fuel pump is probably in fine condition and will probably not need replacing.

Fuel Filter – Gasoline contains olefins and waxy paraffin like compounds.  Fuel vendors add detergents to try and keep these in suspension but there is a tendency for them to deposit onto the surfaces of your fuel system.  Over time, the inside of your fuel tank can become lined with a mixture of these compounds.  Ethanol is very good at mobilizing these deposits and a few tank fulls of E85 will do a good job of cleaning them from your fuel system.  They burn well, especially when mixed with ethanol, and will not harm your vehicle to be removed from your fuel system in this manner.  The trouble is that these waxy compounds may also have been securing sediments to the bottom of your fuel tank.  When these sediments are no longer secured, they will find themselves picked up by the fuel pump and into the fuel filter where they will start to obstruct the flow of fuel.  This problem is most common when budget fuels have been used over a long period of time but most fuel filters are relatively easy to change.  If you think you are a likely candidate for this issue, we recommend using your first few tankfuls and then changing the fuel filter as a preventative maintenance item rather than experiencing a problem when you are in a remote area.

Oxygen Sensors – Your vehicle will have one or more oxygen sensors.  The oxygen sensors enable your vehicle's computer to properly trim the fuel.  The ability to adjust the fuel trim is standard on all modern fuel injected engines and it is crucial that this system be working properly.  If your car is running well on gasoline, your oxygen sensors are probably OK.  Occasionally we have seen some older sensors get soft with age and use.  If, after conversion, your engine runs well on mixtures up to about 50% ethanol but you are having difficulty with higher concentrations of ethanol, the problem may be due to oxygen sensors that are not responding as they should.  If you suspect you may be having this trouble, you can check the electrical response of the sensor.  While it is usually not necessary to do so, oxygen sensors are easily replaced should you experience this issue. 

What model of converter do I need?

This will depend upon the type of fuel injection system you vehicle uses and the number of injectors it has.  The following are descriptions of each of these types.  The one that matches your vehicle will determine the model of conversion system you will need.  If you have questions, please contact our technical support for assistance.

Standard 12V Multi Port – Most vehicles fall into this situation.  Locate the injectors and examine the connectors.  You may need to remove one from the injector to make a match as the outer appearance will vary.  The important consideration is the configuration of the mating parts.  If you are having trouble determining a match, send us a digital photo of the mating end of your connectors and we will help with the identification.  It is also important to verify the polarity of your car's injector wiring.  Each connector has a relatively standard way that it is wired but some vehicles have it the opposite direction.  The easiest way to do this is to examine the color code of the injector wires going to several of your car's cylinders.  There will be a pair of wires going to each cylinder's injector and one wire from each set will usually have the same color code.  This will be the positive wire.  If you cannot find a color code in common, you will need to use a volt meter on the wires.  The injection system can usually be energized by turning the key to the on position.  One of these wires will show a +12V potential over the chassis or negative battery terminal. Note which side the positive wire is on when looking at the face of the female connector as shown in the photos below.

Throttle Body – This is often found on GM V-8 engines from 19XX to 19XX.  There will be a device that looks a lot like a carburetor with two injectors sitting over an intake manifold on the top of the engine.  This is an hardwire installation but it is also one of the easiest installations to perform.  You will need

GM Vortec – These injectors are buried inside the engine but electrically they respond as usual and the standard conversion applies by using a hardwire installation.

Buried injectors – late model V-6 engines will usually have the injectors buried under the air plenum.  Some plenums are easy to remove and some are much trickier.  If you have a complicated air plenum removal situation, you may wish to opt for the hardwire installation as the injector wires are generally easy to access.

Mono Point Injection – There are a few vehicles that have an arrangement similar to the throttle body injection system except that they have one injector instead of two.  Unfortunately, we have not yet had the opportunity to test the electrical properties of this injection system.  We believe using one channel of our throttle body converter may do the job but at this time this solution is untried.

4V injection – We have discovered that a few injection systems on European models use 4 volts instead of the usual 12.  We have only encountered this system on some Volvo and Audi models but are unsure if there are any others that also use 4 volt injectors.  We are investigating a solution for this but our 12 volt converters will not work on these injection systems.  If you have a 4 volt injection system and would like to be notified when we have a solution for you, please let us know. 

Do I need to run special oil, or change it more frequently?

You should always use a grade of oil that meets or exceeds the engine manufacturers recommendations.  There is nothing about the nature of E85 that would normally require special oils or to change them more frequently.  If your driving habits are hard on oil, then you should use a high grade oil and/or change it more frequently.

One of the things that can cause oil to require changing is a buildup of contaminants.  The oil filter should always be changed at every oil change and that will help to keep particulate contaminants out of the oil but chemical contaminants will still accumulate.  These contaminants come from the blow-by.  During the power stroke, hot combustion gases will leak past the rings and valve seals.  These gases are allowed to escape the crankcase through the PCV system but the oil will trap many of the chemicals that are present in these gases.  For example, sulfur in the fuel will form sulfur oxides.  These will gradually build up in the engine oil.  When an engine is first started and not yet warm, water vapor from the combustion will also enter the crankcase and condense on the cold surfaces.  The sulfur oxides combine with the water to form sulfuric acid.  The ethanol part of E85 has NO sulfur or any other elements that would form harmful oil contaminants, so using E85 should reduce the rate oil becomes contaminated with such things.

Grit from the intake air can also enter your crankcase with the blow-by.  Your choice of fuel will not change the amount of grit that is in the intake air.  You should change your air filter when recommended or more frequently if you operate in dusty dirty conditions.

Oil dilution is rare, but can occur if an engine is running excessively rich.  If your engine is in good working order, this will not be a problem whether you are using gasoline or E85.  Vehicles from 1996 will have level 2 on board diagnostics that will detect a rich condition and alert you with a check engine light.

Oil can breakdown due to heat and pressure between bearings.  Converting a vehicle to E85 can significantly increase its performance potential.  If you make a habit of using this extra performance, you are placing your engine into a situation which will more quickly cause the engine oil to loose its lubrication.  Note that this does not require street racing.  If you find that your SUV is able to pull your boat up the mountain pass 10 MPH faster than before, you are spending an extended period of time with your engine at or near full-throttle.  This is hard on ordinary oils and if you read most owner's manuals, the manufacturer would classify towing as hard service and recommend more frequent oil changes.

What do we use in the FFI Hummers?  These vehicles are using a full synthetic oil.  First, the increase in fuel efficiency will often pay for the difference in the cost of the oil.  Second, we want our vehicles to stay in top shape and last a long time.  Third, while we don't drive like maniacs, we do pull trailers and use these vehicle's off-road capabilities and want an oil that will keep the engines lubricated properly.  We think it is a good investment. 

I've heard that E85 will harm my engine.  Is this true?

A definitive answer is, “it depends”.  The 1973 oil embargo caused fuel shortages and prices rose dramatically.  This spurred America to find both alternatives to gasoline and ways to extend the fuel supply.  One thing that was noticed was that an engine could burn a mixture of alcohol and gasoline and the resulting product was called gasohol.  There were a few problems that were encountered.  First, the alcohol that was typically used was wood alcohol or methanol.  Methanol is much more corrosive to many common materials than is ethanol and unfortunately most of the vehicles that were on the road in the 1970s were not designed to have alcohol in the fuel.

As a result, gasohol had a short duration on the market but congress was determined to reduce America's dependence upon foreign oil.  Tax incentives for the production of ethanol were established and there were several executive orders to use gasohol in the vehicles that could safely utilize it.  In 1982, another fuel shortage occurred and it was obvious that alcohol blended fuels were coming.  The manufacturers changed the engineering of the vehicles to be more chemically compatible with the presence of alcohol in the fuel.

Ethanol is a much better alcohol to use for fuel than methanol.  For most materials, it is less corrosive, it has considerably more energy, and is also far less toxic.  For several years, it has been common to blend ethanol into the gasoline supply.  E10, a mixture of 10% ethanol and 90% gasoline is available at many vendors.  Blending a couple of percentage points of ethanol into the gasoline is not only common practice, but in many areas it is being required.

What we have found is that if your vehicle was manufactured in 1990 or later, the fuel system and engine were most likely made with materials that are not sufficiently reactive to ethanol to be a problem using E85.  If you have an older vehicle, you will need to investigate whether or not the fuel system can use ethanol.  The most common material that was a problem is rubber.  If you use E85 in a vehicle with rubber fuel system components, they will deteriorate fairly quickly and fail.  This could cause fuel leaks and result in a significant risk of fire.  If in doubt, older vehicles should have their fuel lines and fuel pumps replaced.  Most auto parts stores should be able to supply you with the parts necessary to make this change. 

Do I have to change my injectors?

We have found that the stock OEM injectors on late-model engines work fine with E85.  Unless you are building a race car and need a high performance injector, the ones your engine already has should be OK.  Ethanol is also an excellent cleaner and works to keep the injectors, fuel rails, and valves free of deposits, so you also do not have to have your injectors cleaned.  The ethanol will do that for you.

Do I need to change my oxygen sensors:

If your engine is running fine on gasoline, your oxygen sensors are probably working well and you should not have to change them.  Sometimes these sensors can be degraded through age and use and will not respond as well as they should.  In this unlikely event, your engine's computer will have difficulty making proper fuel trim adjustments.  If you convert to E85 and find that your engine runs fine with ethanol mixtures up to about 50% but has difficulty with 85%, the problem may be due to soft O2 sensors.  A mechanic can diagnose whether this is the cause by examining the electrical response of the sensors.  If an O2 sensor is found to not be responding as it should, they are easy to replace.

Are there any other sensors that need to be added or replaced?

All of the sensors that your vehicle was equipped with need to be in good operating order if your engine is to perform as it should.  Some factory flex-fuel vehicles added an alcohol sensor to allow the computer to determine the alcohol content of the fuel but that practice was discontinued by all of the manufacturers of factory flex-fuel vehicles.  Our conversion system does not require you to add any sensors.  All computer controlled fuel injection systems monitor the oxygen sensors to determine if the proper fuel to air mixture has been achieved and will adjust the fuel trim to achieve the proper ratio.  This allows the engine to adapt to varying fuel grades and prevents the engine knocking that was so common with the carburetor based systems.  Our converter extends your engine's built in ability to trim fuel.  By extending this fuel trim range, our converter allows most vehicles to use any mixture of gasoline and ethanol without requiring any manual intervention. 

What is the octane rating of E85?

There are, of course, several variables such as the exact mixture of ethanol in the gasoline and the grade of gasoline used but E85 should result in an effective octane of approximately 105.  It is very resistant to predetonation (knocking) and works very well in high compression engines.

How much will my MPG be affected?

There are a lot of variables here.  Ethanol has less chemical energy per gallon than gasoline.  It burns more efficiently however, so while you will get fewer miles per gallon, you will get more miles per BTU.  The increase in the burn efficiency will partially offset the difference in the energy levels of the two fuels.

Driving habits have a large impact on fuel economy.  Running on E85 generally results in a noticeable increase in performance.  If you make a habit of using the extra performance, you should not expect it to have a positive effect on your MPG.

This is definitely one of those “results will vary” situations.  Our customers have reported MPG differences generally ranging from 5% to 20% lower for E85 than when running on gasoline.  Other than driving habit changes, the most common factor seems to be that the higher the engine's compression ratio, the less the mileage loss.  We have customers who claim their Toyota Prius will get essentially the same mileage on E85 as it did on gasoline.

If you are driving conservatively in an average car, you will probably see a 15 to 20 percent loss in mileage.  If you are on the high end of the MPG loss of approximately 20%, then to achieve the same cost per mile, you should look for a 20% price differential between gasoline and E85.  If the regular grade of gasoline is selling for 3.00 per gallon, you need a 60 cent differential in price and would look for E85 selling for 2.40 or less.  In areas where E85 is readily available, there is often more than a 60 cent difference in the pump price.

Due to the high octane rating of E85 (approximately 105), it is an excellent alternative to buying premium for high performance engines.  Premium is often 20 cents or more above the price of regular.  If your engine needs premium, converting to E85 will be an even more attractive option. 

Can I use pure ethanol?

In the US, the answer is no unless you want to pay the beverage tax.  The highest concentration of ethanol that the US allows in fuel grade ethanol is 98%.  The other 2% is gasoline, thus rendering it unfit for drinking but doesn't really change it's combustion characteristics.  In 2007, the Indy 500 used this fuel.  It has an octane of 120 and the performance you can achieve is phenomenal, especially in high compression, turbo, or supercharged engines.

It is difficult to find E98 for retail sale but is the concentration that will be loaded onto trucks when the ethanol leaves the production facility.  If you don't want to brew and distill your own fuel, you will need to talk to an ethanol distributor or blender to obtain E98.  If you are running a race car and are paying for 105 octane gasoline, you will want to take a serious look at converting to E98.  With this high an ethanol content in your fuel, you will want to adjust your converter to a higher setting, probably in the 8 to 10 range.  This will enable easier starting and maximum power.

For the average individual running an ordinary vehicle, the performance difference between E85 and E98 is probably not worth the trouble but with our conversion box, you can do so if you wish.  We have tested E98 in both of our Hummers and in a 2003 Dodge Dakota with a 4.7 liter V8.  The power increase is remarkable but remember, you didn't upgrade your transmission...  Driving hard is hard on the equipment.

I've heard that it can be hard to start your vehicle on E85 in cold weather. 

Some vehicles have more trouble with this than others but in general, it is true, even of factory flex fuel vehicles.  Most of the reason has to due with the nature of the fuel.  It is harder to start a cold engine on ethanol.  The higher the percentage of ethanol, the sooner this will become an issue.  One of the reasons you won't normally see a blend of ethanol beyond 85 percent is that the 15% of gasoline helps with engine starting.  Most E85 vendors in colder climates will down blend the product during the winter to approximately 70% content.  In fact, if you read the fine print on some of the pumps, it will say, “Contains a minimum of 70% ethanol.”  This is a good thing since at 70% ethanol, cold starting issues generally disappear.

Fuel Trim – having the correct fuel mixture when starting is a big advantage.  Many of the newer vehicles will remember the trim they were using when last shut off.  If you have a vehicle that remembers its fuel trim, you will have fewer cold start issues.  If your vehicle does not remember its trim, it must make some average assumptions, start the vehicle, and wait for the oxygen sensors to reach approximately 600 degrees before it can adjust the fuel trim.  Our CFO's 2003 Dakota is like this and will trim its fuel in approximately 45 seconds from a 60 degree (F) start.

Converter adjustment – To have the ability to run either fuel without opening the hood and making adjustments, we ship the converter adjusted to 6 (see adjusting the converter).  This setting works well for most vehicles and allows the vehicle's fuel trim system to trim lean enough to run with gasoline and to trim rich enough to run E85, just by watching the oxygen sensors.  Since E85 is not always available, it is important to be able to do this.  If you always run E85 and are having some cold start issues, you can adjust the setting inside the converter to a higher (richer) setting.  If you set it on 10, cold start problems will probably disappear but you will also probably get a check-engine light with a rich condition if you should run gasoline.  If this happens, it will not harm your engine.  Simply readjust to a lower setting.  Once the rich condition is corrected, the check-engine condition should clear on its own.

Why is an engine harder to start on ethanol? 

Vapor Pressure – The first difference in these fuels is that ethanol has a lower vapor pressure than gasoline.  This means that while the cylinder head is below the boiling point of ethanol, gasoline will more readily vaporize.  Since there is very little time from when the injector squirts the fuel to when the spark plug will attempt to ignite it, this can make for significantly less of the ethanol to have turned into a vapor than would have happened for the same amount of gasoline.  Liquid fuels do not burn.  To compensate for this, all engines will add extra fuel when starting as it is the fuel to air mixture OF THE VAPOR that matters.

Carbon-Carbon Double Bonds – Gasoline ignites more easily than ethanol.  There are fundamental differences in the physical chemistry of these fuels.  In order to start and then maintain a combustion chain reaction, you must have fuel as a vapor well mixed with oxygen and have sufficient kenetic energy (heat) in the molecules to destroy the existing molecular bonds in the fuel and reform bonds with the oxygen.  Double bonds are easy places for an oxidizer to attack a fuel molecule.  Because the double bond is easy to attack, it lowers the energy required to break the first bond when a fuel contains a double bond.  Additionally, when conditions for combustion are marginal, the presence of double bonds in the fuel will enable combustion when it would otherwise not occur.

Gasoline – Gasoline is mostly a mixture of various alkylates, all of which contain a double bond.  This prevalence of double bonds in the molecules of gasoline results in a low flash point.  It is easy to ignite and is not very picky about the fuel-to-air mixture in order to maintain combustion.  Of course clean combustion requires a correct mixture, but to have combustion at all (and get the engine started) you need only be remotely close.

Ethanol – Ethanol, C2H5OH, has no double bonds whatsoever.  There is no easy attack point.  For an oxygen to steal away any part of this fuel, it has to have significant energy or it will fail to break any of these bonds.  Because of this, in order to have combustion, the conditions for must be closer to ideal than for gasoline with its abundant double bonds.  Even with 15% gasoline, E85 has a much lower concentration of double bonds and is therefore harder to ignite.  Increasing gasoline content to 30% provides an adequate concentration of double bonds to assist in sustaining combustion when conditions are poor.  This is why you will often see a 70% blend during cold winter months.

Gary Ackaret FFI - 2007 - All Rights Reserved

Additional E85 Facts

First of all, what is E85?:
E85 consists of 85% ethanol and 15% additives. The additives vary a lot depending on where you live and time of the year. But roughly, the 15% additives is mostly made up of gasoline, additives that helps the engine to make a complete burn, additives that helps the engine start when it’s cold and additives to color the fuel and the flame (so you know what substance it is, and also to help you see that it is really burning).

(Positive) facts about E85:
1. It is not corrosive to the fuel system or the engine. This is a myth and ethanol is often confused with methanol, which actually have corrosive properties. I’ve run my car for well over two years on E85 without a problem. Some models before 1988 on the other hand may have some parts that are not ethanol resistant. If we are talking Volvo’s, then this mainly applies to the non-electronically injection systems such as K-jet etc. Most cars with electronically fuel injection (EFI) should be resistant to ethanol. Some people say it would kill your engine right away and that you should buy there race fuel instead (of course they say :eyes: )

2. It is not as harmful to the nature/environment as gasoline or any other petroleum products for that matter. Ethanol is made out of renewable energy resources such as crops and trees to name a few things. The carbon dioxide that an ethanol powered car emits is not contributing to the greenhouse effect, but is taken up by the plants and is being "re-used". The carbon dioxide then goes around in a closed loop. Gasoline on the other hand is made from oil that comes from old dinosaurs , plants and other stuff 100 000 of years ago, and it doesn’t take part in the closed loop but only adds to the amount of greenhouse gasses. Ethanol is also easily bio-degradable if it should leak into our environment.

3. E85 is 104-105 octane and therefore it's more knock-resistant and can tolerate more boost or a higher CR. E98-100 is about 120 octane.

4. E85 cools the intake charge more and therefore it's more knock-resistant and can tolerate more boost or a higher CR. And it also makes the engine run cooler and to some degree, even safer.

5. E85 is in most cases at least 5% more efficient than gasoline at the same lambda value (up to 25% more efficient on some cars optimized solely for E85). Mill your heads

6. Since E85 has very good cleaning properties as well as leaving behind a rest-product of water, it is cleaning the fuel system and it will keep the injectors nice and clean. The combustion chambers, valves, ports and the exhaust will also be clean(er), almost like the car had water injection.

7. In most cases it will cost less $/mile to run on E85, and as we go into 2008 and many new plants come online we will see the price difference get even better.

(Negative) facts about E85:
1. Cars running on E85 have some trouble starting when the engine temperature drops below +5*C. Cars running E100 (not very common) have some trouble starting when the intake (the air) temperature is below +15*C. This is easily solved by using an engine heater in the winter, electrical or fuel-heated (this is recommended on all cars regardless of fuel to get better mileage, less wear on the engine and less impact on the environment etc., but that is another matter to discuss and will not be brought up here...). Some people also adds a little extra gasoline to the tank of E85 to help with cold-starts.

2. Since cars running E85 requires roughly 10 to 30% more fuel, a tank of E85 will not get you as far as a tank of gasoline and you will have to refuel more often. This is often disregarded by E85 users who learn to live with it because of the economical gains from reduced price of E85.

Technical facts about the mentioned fuels:
E85 requires 39% more fuel to reach stoich even if that is not what you may come up with when doing calculations based on the table below. This is because the injector flow is slightly different when using E85 among many other things I can't really think of at this time (will be added at a later time).

Fuel ........................ AFRst ........ FARst ....... Equivalence Ratio ... Lambda
Gas stoich ................ 14.7 .......... 0.068 ................ 1 ................... 1
Gas max power rich .... 12.5 .......... 0.08 ................. 1.176 .............. 0.8503
Gas max power lean .... 13.23 ........ 0.0755 .............. 1.111 ............. 0.900
E85 stoich .................. 9.765 ....... 0.10235 ............ 1 ................... 1
E85 max power rich ...... 6.975 ....... 0.1434 .............. 1.40 ............... 0.7143
E85 max power lean ..... 8.4687 ...... 0.118 ............... 1.153 .............. 0.8673
E100 stoich ................ 9.0078 ...... 0.111 ............... 1 .................... 1
E100 max power rich .... 6.429 ........ 0.155 .............. 1.4 .................. 0.714
E100 max power lean .... 7.8 .... ...... 0.128 .............. 1.15 ................ 0.870

Ethanol reaches max torque at richer mixtures than gasoline will.
The term AFRst refers to the Air Fuel Ratio under stoichiometric, or ideal air fuel ratio mixture conditions. FARst refers to the Fuel Air Ratio under stoichiometric conditions, and is simply the reciprocal of AFRst.

Equivalence Ratio is the ratio of actual Fuel Air Ratio to Stoichiometric Fuel Air Ratio; it provides an intuitive way to express richer mixtures. Lambda is the ratio of actual Air Fuel Ratio to Stoichiometric Air Fuel Ratio; it provides an intuitive way to express leanness conditions (i.e., less fuel, less rich) mixtures of fuel and air.

As you can see from the table shown above this section, the ideal target AFR´s under boost for both gasoline and E85 are listed. For gasoline it's 13.23-12.5, and for E85 it's 8.47-6.975. However, with E85 you will not need to richen the mixture under WOT/boost as far as 6.975 or beyond. It does not need to be proportionally richer when compared to gasoline.

Why? Again, Because the fuel has a cooling effect on the intake charge and the space in which the combustion occurs. And at such a low AFR as 9.765 (lambda=1 on E85) or lower the fuel cools pretty good, don’t you think so?

Many people with some experience in mapping an ECU for use with E85 says that as high AFR as 8.5 or lambda=0.80-0.85 works well. No need to go to the extreme end of the useable scale to get safe power. It only uses a lot of fuel without giving any benefits.

E85 burns faster than gasoline at best mixtures so it is an inherently more efficient fuel. It also produces more exhaust gas for a give weight of fuel air mix giving higher average cylinder pressures in spite of lower EGT's. With straight E85 in a properly tuned car its good for about +5% power / torque increase. I suspect on a turbocharged car the benefit is larger.

Since you don't have to richen the mixture as many percent (proportionally) as you have to on gasoline, you can make more power without having to use as much fuel.

How does ignition timing change on E85 ?
Timing on ethanol blends will not change very much. MBT timing for both gasoline and E85 are very nearly the same at light to moderate engine loads. At high engine load the E85 will want just slightly more advance. The big difference will be fuel/air mixture. The E85 will give improved torque with much richer mixtures than gasoline. Both gasoline and E85 will give best thermal efficiency at about 15% rich of stoich, so the equivalent of 12.78:1 on gasoline would be about 8.5:1 on E85, but E85 will continue to give better torque numbers up to about +40% rich of stoich or 7:1 mixtures, so on a utec you would want to richen up your WOT high load cells and add a tweak of timing to get the most out of E85 from what I've read. I run my car on 8.3:1 right now. I have tried much richer mixtures but i have not compared it on a dyno yet.

Quote:
Are you sure you don't mean that E85 will allow more advance?
Just passing on what I've found in the various sources. Logically you are correct, but one source says simply that MBT timing is the same for E85 and gasoline, and another report says at low loads the E85 and gasoline like the same MBT timing but at high loads MBT timing for the E85 is slightly more advance.

I suspect this is due to them not running ideal max power mixtures but cannot confirm it. Burn speed for E85 changes quite a bit with mixture, so if they were just a little bit lean or rich of ideal the burn rate would be lower.

Lots and lots of variables not well covered in some of the sources and in general they are focusing on emissions issues not max power torque so that would incline them to use less than best power timing advance. In a couple of the reports they also had limited control authority over timing and may not have explored the extremes very thoroughly.
I have also read that E85 burns much quicker than gas at rich mixtures so if you have your timing advanced and go WOT you could get power loss (And you might not pick up any knocks) because of the burn speed being to fast.