Landracing Forum
Tech Information => EFI Questions => Topic started by: rouse on May 20, 2015, 11:53:40 AM
-
I am sitting hear with a question that I'm on the fence about.
I am going to run alcohol and setting up the EFI from scratch, so do I go with Methanol or do I go with Ethanol?
Air cooled engine on Motorcycle if that helps weight the call, or is it just a 6-1 half dozen the other?
This is only a fuel question we'll make the EFI work with the final choice.
Rouse
-
The methanol will make slightly more power but its down sides are:
More toxic (skin absorption)
Much much more aggressive at inducing corrosion, so have to carefully select materials in the fuel system.
Higher fuel flow required which results in larger injectors needed to pass enough fuel which sometimes make it difficult to source big enough injectors or if going for high rpm having enough time for injection pulses (if using timed injection vs constant flow). Sometimes solved by using 2 injectors on each runner, one for low throttle opening giving good idle and minimum fuel wash down of the cylinder walls then cutting in the high flow injector at WOT.
If you are not bound to alcohol only and only planning on going fuel, I would go with E85, it has almost the same energy as methanol, easier starting, better self lubrication, easier to buy in most locations and gives a visible flame if you have a fuel fire. It will start reliably at cold temps vs issues which sometimes occur getting a methanol or straight ethanol engine to run at temps near or below 50 deg F.
Both run cooler than straight gasoline for the same power output on max power rich mixtures and ethanol E85 and methanol will all make more power than straight gasoline for a given air flow in the intake.
-
Question.....how well does E85 work with nitrous oxide?
Bill
-
One other advantage of E85 is that far more tuners have experience with it, so you should be able to get tuned quicker and safer for the engine.
-
I know that the sprint car guys run methanol so it is readily available; is ethanol as available as methanol?
Regards, Neil Tucson, AZ
-
VP makes some methanol blends with fewer noxious side effects. They are in Texas and not far from you. They might be a good source of info.
-
I switched over this season to Ethanol (with nitrous), notice I didn't say E85. I considered Methanol, but due to too many unknowns on my part, I tried E85 first. However, I would strongly suggest to NOT use pump E85 due to it's inconsisentcy. The last event last year, I did the switch to E85 from VP Import and hurt the motor on the first pass. Over the winter I did a lot of head scratching and research, I have found out that it's not the 85% ethanol that is the concern, it's the 15% of what ever the gasoline company's decide to use on a given batch. You could easily get 5 gallons from your local station that does great or 5 gallons of engine killer. I found that the gas folks can put whatever they darn want into that 15% as long as the perceived octane is 95 or better and your car/bike starts. It could be 70 octane gas, it could be other chemicals they want to get rid off, what ever goes. Works fine for your flex fuel car, not so much spraying nitrous.
The Ethanol I am using is 90% ethanol with additives that bring the "octane" up to 114. Sold by Ignite Racing Fuels out of Indiana. They also make a 107 that is blended with 94 octane gasoline.
-
Yes pump E85 can be an issue depending on where you live, just like pump gasoline the blend changes summer to winter, and folks with bleeding edge tunes can have problems if the take a car tuned on summer blend E85 and run it on winter blend E85. For those folks there are two options. You can buy performance E85 in drums or cans which has a known blend, or buy straight E98 and blend your own custom blend.
Our local drag strip fuel farm sells straight E98. The other option is to buy summer blend from a station you trust in drum quantities during the summer before the winter blend switch and store it over the winter. If you go to the station owner you can usually find out exactly what blend they have in the tank by having them check their delivery tickets, or using a hydrometer to check the specific gravity, or doing a "water test" yourself.
Water test: mix a small amount of E85 with a known quantity of pure water and that will force the gasoline component to settle out if you use enough water. Then you can subtract that gasoline content from the original fuel volume to figure out the gasoline/ethanol ratio.
E85 and nitrous work very well together!
E85 fuel ethanol content seasonal changes
E85 fuel blends change content seasonally just like all gasolines blends change with the seasons. This seasonal change in blend for E85 is primarily to improve cold weather starting, where the changes in gasoline during cold weather is to improve cold weather starting. In the summer months, gasoline must be blended to reduce vapor lock and to reduce evaporative emissions.
The recommended dates for changing E85 fuel blends are listed in a chart in the E85 handbook on page 33-34, which is in the "E85 Fuel Specification" tab.
The Volatility class specifications are broken down on page 10.
Volatility class 1 --- minimum ethanol 79%
Volatility class 2 --- minimum ethanol 74%
Volatility class 3 --- minimum ethanol 70%
As you can see each region has a different start date and recommendation for seasonal blends depending on local weather climate.
Here on the high plains east of the rockies in Colorado we run the class 1 fuel blend from mid June -- mid Sept, run class 2 fuel from mid Sept -- mid Oct and run the class 3 fuel blend from Mid Oct -- mid April, then back to the class 2 blend from mid April to mid June. The standard only specifies a minimum ethanol content, vendors can run higher ethanol content if it is economical. If it is cheaper for the fuel blender to add more he can. Ethanol content is bottom line driven by local weather conditions, and cold starting problems for local drivers just a gasoline blends are modified to give easier starting in cold weather.
In the Southern part of Texas they would never go to a class 3 blend, and in Wisconsin, they would only have the class 1 blend for about 2 months in the summer. In Florida they would be on class 1 almost all year long and in North Dakota and Wyoming and Montana, they would be on class 3 almost all year long.
Testing ethanol content with the water test
The proper way to do the water test is specified on page 38 of the handbook.
Handbook method:
http://www.afdc.energy.gov/uploads/publication/ethanol_handbook.pdf
2.1 + 1.94 x (total vol - lower meniscus) = hydrocarbon
ethanol = 100 - hydrocarbon
Ethanol bonds very strongly with water so the percentage is not a direct relationship as seen above in the formula.
For example, If you add 10 ml of water to 100 ml of standard pump gasoline, and end up with 17ml of phase separation -- you have a full E10. (yes I know the math does not work but this is due to ethanol's bonding properties) In this case 10 ml of water and 10 ml of alcohol bond to form a mixture of 17 ml of water alcohol mix.
-
I ran blown Methanol back int the 70's, but time has passed and new things have come to be the standards. That's why I'm asking about the two now. Chance are that I will end up with what sounds the best, Hopefully that's what will run the best.
Good information so far.
Rouse
-
One other thing to consider in the choice between methanol or ethanol is the latent heat of evaporation, this is the property of the fluid that provides a cooling effect to the inlet air. The latent heat of evaporation for ethanol is 364 btu/lbs and 473 btu/lbs for methanol, combine this with the requirement of running about 1/3-1/2 more methanol to get equal power levels and you are looking at a pretty significant difference in the potential to drop the temp of the inlet air charge. The rule of thumb is a 1% power increase for each 10 deg F reduction in inlet air, going with methanol could certainly have the potential to make more horse power especially if you are supercharged or turbocharged. I think I would stick with methanol.
Rex
-
The build will be natural aspirated, and yes the heat of evaporation could make a difference. There no way not to count that as a plus for methanol. Tuning with EFI may be the deciding factor when every thing is said and done, as far as the choice between the to.
I could see 6 or 8 more horsepower with methanol, but would the tuning issues with EFI out weight the difference?
Rouse
-
There are two sides to that advantage how ever, Methanol fuel flow required is so high that it dilutes the intake air flow and you need to flow more fuel air charge.
Some recommend over sizing intake tract and valves by about 10% over what would work best for gasoline due to the dilution effect of the methanol and cold wet flow which has a lower critical velocity. Critical flow in a tube or orifice is determined by the local speed of sound in the gas mixture. That means that a hot gasoline air charge will choke at a higher flow velocity than a cold wet methanol charge in the same manifold intake valve size.
By choke flow I mean reach the critical flow in the runner which will not allow any more flow to occur regardless of pressure differences between the plenum and cylinder.
I think over all methanol and E85 are essentially identical in terms of power potential if the build is optimized for each, E98 straight ethanol comes in a very close second to those two in power potential but is a little harder to find in some areas (racing methanol is available most everywhere, E98 is a bit harder to find in areas where fuel ethanol is not actually produced and needs to be shipped in (cough Calif Cough -- although that might have changed in recent years)
Bandimere Drag strip here in Denver has had E98 available at the fuel farm for a long time, but smaller local strips in the area not so much.
I prefer E98 and E85 due to the lack of corrosion and lack of toxicity, other than that it is pretty much a toss up among the three if you optimize the build for each.
In the turbocharged imports with mechanical compression ratios of 8:1 they can run summer blend E85 at 35 psi boost without detonation.
-
For what it is worth: my engine has been very consistent over the years (made some changes this year, so no comparisons now) and since I own a dyno and tune bikes, my bike lives of the dyno when it's not racing. Here is what it made on different fuels N/A with a proper tune.
VP Import - 202 wHP
C16 - 204 wHP
Pump 93 - 207 wHP
Pump E85 - 212 wHP
-
That's the kind of information I was digging for HR,and RT Thanks.
I can tell you that the heads are nearly done %%to go, and the idea of increasing the choke volume for methanol was not taken into account.
That leaves me closer to giving race quality E85 the nod, or E98 with 13% +/- are so of good race gas.
The percent of gain RT saw is nice too. The injectors I have will handle E85 just fine, but I'd have to go up a notch for Methanol, and chance are the ports we have may not support the extra fuel requirements as they are.
Rouse
-
Good thread!
-
I'd go with ethanol preferably Jack Daniels. You could always drink it it if the engine blew.
-
Great thread, and the interesting thing?.... E85 don't cost as much as some of those other speciality products.........
-
The JD sounds like it be the call, but it has to much water :-D
I will run E85 starting with E98 and blended, that way I'll know what the 15% composition is.
Racers spend to much time, effort, and $$ to just roll the dice on fuel mixtures that are inconsistent as E85 tends to be.
I am supposed to be getting parts for the build coming in this week and we'll build to that Fuel.
Rouse
-
As an old air racer crew chief that had to deal with water/alcohol injection, I know what the military research found out as far as the best alcohol for combustion properties,,,,,,
METHANOL
Robert "Smitty" Smith
-
As an old air racer crew chief that had to deal with water/alcohol injection, I know what the military research found out as far as the best alcohol for combustion properties,,,,,,
METHANOL
Robert "Smitty" Smith
I agree Smitty, however, at this point I have to much momentum headed in the wrong direction for methanol.
Ie. the injectors, heads, ports, are all sized for E85.
Rouse
-
Actually when they did comparative testing ethanol and methanol were interchangeable in ADI (water injection systems) in high performance WWII aircraft engine applications.
They used a mixture of methanol and ethanol in very low temperature environments to get the high concentrations of alcohol they needed to achieve freeze protection and best performance.
The only reason they used methanol was it was poisonous so the GI's were not likely to steal it and drink it. It is also cheaper to make and untaxed. During the research at Pratt & Whitney, they got a supply of high proof ethanol for testing and they got a tank car escorted by U.S. Treasury agents who were worried about it being diverted to "medicinal uses". Remember this was shortly after prohibition ended.
The Navy used ethanol for their torpedoes (so called torpedo juice) because it was much less toxic than methanol and just as effective in the torpedo motors. They did have problems with the swabbies skimming some off to spike their punch.
Best easily available document on the development of water alcohol ADI systems for high performance aircraft is probably this PDF.
http://www.enginehistory.org/Frank%20WalkerWeb1.pdf