Originally Posted by hotrod

Here is my 2c on this topic.

Converting engines to E85 raises some interesting questions. You actually have two different issues here. One is for a basic conversion by someone who only wants to make a conversion with largely existing equipment ( ie minimum investment in order to cut fuel costs, to get some of the benefits of a superior fuel or as a political/social statement regarding foreign oil independence or renewable fuel concerns) For those folks the conversion is really pretty simple.

If you are on the other hand looking at an "optimized conversion" where you are custom building a setup to get the most out of E85 --- than that is a whole different ball of worms.

For the "basic conversion" You only have a couple of issues to worry about.
1. Ignition timing changes are not necessary E85 and gasoline use almost identical ignition advance at both max power and max effeciency.
2. Fuel flow increase to adapt to the different fuel. In this case your most important concern is to increase fuel flow by about 27% give or take a bit so the engine is working with an ideal mixture.
3. Fuel system component compatibility ( modern rubber fuel lines are ethanol safe) Some fuel pumps, and gasket materials may have issues.

On modern OBDII electronic engine management systems, almost no changes of any kind are needed at fuel mixtures of 33% and below of E85. The modern ECU's have enough fuel trim authority to adapt to these mixtures. If the user is willing to live with some CEL's and a slight lean out under max power, you can push that up near 50% mixtures with no changes at all. For mixtures between 50% E85 and 100% E85 you need to increase the fuel system flow capacity by using larger injectors, increased fuel pressure etc.

On the EFI systems, if there is a user tuneable or (vendor tunable) ecu reflash or adjustable piggy back tuning solution, you can optimize the fuel mixture by using commonly understood tuning modifications.

Generally you richen the mixture about 27% across the board. At max power if performance is the goal you will want to run it even a bit richer as Ethanol based fuels continue to make more power at up to 25% rich of stoich mixture where gasoline reaches max power at about 15% rich of stoich. EDIT I have one source that says you can go up to 40% rich of stoich on E85 and still get increased torque. On carburator systems you may need to enlarge fuel inlet sizes and ensure the needle and seat material is compatable with ethanol fuels.

For max fuel economy the ethanol based fuels produce more torque at lower throttle openings and their higher fuel octane and cool burning characteristics will allow you to lean out the light throttle low load cruise portions of the fuel map father than you would dare on gasoline.

On an optomized carburator system, basically all the above applies but it is a bit more complicated to get there. For an average driver, only interested in getting the car to run well on the new fuel. Richen the primary jets about 27%, and the secondary jets a bit more. You will probably want to increase the accelerator pump shot and may need to modify the idle mixture sytem slightly to get good drivability. You may need more carburator heat, and or more agressive choke settings in cold weather.

Any tuner that is good with carburators should be able to dial in a setup with a bit of experimentation. There are a handful of shops that build custom carburators for racers that run methanol fuels and an E85 conversion carburator would be a pretty simple adaptation of their methanol carb design I would think. Call around and see who builds "alcohol carburators" for the racers and they should be able to get up to speed pretty quickly.

Once you get to trying to optimize the engine for a high ethanol fuel like E85, you would be making pretty much the same modification the methanol fuel class racers do to their engines with the exception that your fuel flow rates would be a bit lower. Due to the higher octane you would run a higher compression ratio ( up to 13:1 or so on NA engines).

Wet flow in the intake manifold of carburated systems is more critical due to the higher volume of fuel dropplets and strong charge air cooling of the alcohol fuels. Alcohol fueled engine tend to like heads and manifolds that have higher air flow capacity by about 10% ( actually ports shaped for slower mixture velocities but higher flow, bigger intake valves, more cam etc. ). The engine can make use of the higher volumetric effeciency where on gasoline it would have gone over the edge into detonation with the higher flow intake system. The increased torque and higher compression ratios, with the alcohol fuels largely gets rid of low speed drivability issues that the larger intake flow and more agressive cams would create on a gasoline engine. The Alcohol fueled engine may also prefer a larger header tube size for performance applications (ethanol produces more exhaust gas volume than gasoline does).

Fuel drop out is more of a concern for max power engines running alcohol fuels, as is keeping the mixture in suspension. Engines can run with slightly warmer thermostats to aid cold weather drivablility, and keep oil temp up high enough to keep from building up fuel in the oil due to the very rich mixtures racers run. Modern synthetic oils appear to work just fine with E85.

A smaller cooling system may be useable on the E85 setup than you could get away with on gasoline. In some cases you may want to intentionally lean the fuel mixture out a bit to get some heat in the engine. In carburated engines they my like more intake manifold heat in cold driving conditions.

Due to the lower exhaust gas temp, catalytic converters light off slower (or fail to light off) with alcohol fuels, so more attention should be made to keep heat in the exhaust system prior to the Cat.

Older vehicles (pre-1980's) may have some fuel system compatability issues with carburator floats, fuel hoses and seals. Cork based carburator gaskets have been known to cause problems on some cars as have Plastic foam carburator floats. Remove any magnesium or zinc in the fuel system, keep an eye on aluminum if it is constantly wetted by fuel and open to the air so it can absorb moisture ( ie carburator float bowls). Anodized aluminum is safe as is stainless steel, mild steel, nickle plated brass and bronze fuel fittings. Mixing many dissimilar metals in the same fuel system should be avoided. ( things like copper tubing, aluminum etc may set up electrolytic corrosion if in the same system. Much like underwater corrosion control in boats, highly reactive metals like Zinc and magnesium are to be avoided)

Some Plastic fuel tanks may have issues with E85, Older fuel tanks coated with "tern" metal ( a lead based coating) may slowly have the internal metal coating stripped off due to this sort of electorlytic action.


Quote:
What can a person do to convince a company like Holly or Edelbrock to make a 50-state legal conversion kit like they do for aftermarket performace products?


1). Get the EPA to quit publishing regs that prohibit changes out right, and set performance based standards.

2.) Create enough economic demand that it is profitable for them to jump through all the necessary hoops.

Hope that helps.

Larry