Okay guys, I would like to try having an alcohol discussion again. Lets see if we can't be grown up about it, leave the politics out of the discussion as much as possible, we can talk about this without getting our thread locked. personal put-downs aren't helpfull, so lets play nice and try again.....I'm very much intearested in ethanol in the fuel we use in our trucks. I think it is a good idea. And I mean ethyl alcohol C2H5OH, not methyl alcohol ( C1H3OH ) I think there has been some confusion there. What I have in mind is an engine with about 11 to 1 compression and E85 fuel. It is already for sale in some farm communities. I have never had or seen any of the alledged problems with seals being hurt by alcohol, or seen hoses that have gone bad either. Now, an old hose with cracks and dry rot might swell up when exposed to alcohol, so I plan on using new neoprene rubber hoses where needed. I'm wanting to use a Holley carb with brass floats, I don't know if the nytrophil floats will tolerate the alky. And where to start on the fuel mixture ? I know the methanol racers use about 6 to 1 fuel ratio......so I'm wondering if 10 or so to 1 might not be good place to start with E85 ? Whad'ya think ? DF
I seriously thought about doing that on the 390 I'm building. I think for an alcohol only motor, you may even want a little more compression. You may want to do some research there. My determination was that there is not enough supply of it to make it worth it. The closest place to me that sells it is 50 miles away. If you built the motor for ethanol, meaning high compression, you may get mileage to equal gasoline. The problem is, that ethanol costs more than gasoline right now. That situation could change, though. Right now, it simply doesnt make economic sense to build an ethanol motor. It may be kind of a fun project, though. It is definately something that I am keeping an eye on, and if the gas prices go up to where they are in europe, it would make sense, and I'd be building ethanol motors.
For your carburetor set up, if your not running a lot of horsepower, you can jet it richer and it may work. I dont know if the ethanol will eat the rubber in the power valve and accelerator pump or not. According to my book, strait alcohol requires about a 6.5-7.5:1 air to fuel ratio. E85 might be ok with 8.5 or 9:1. Typically you'll want to keep a lower airflow carburetor on it, like a 600cfm Holley. Reason being is that the fuel circuits may not keep up with a higher airflow carburetor, and high speed leanout could be a problem. On a street engine this should not be a problem.
DF, the other alcohol thread you started is still current. It did as you say, get political and off topic towards foreign oil dependancy, but it was never locked.
I'm thinking though, since your current topic on alcohol fuel is more centered around mix ratio's and construction materials of the fuel system, it may be better suited as a topic for the Fuel Injection, Carburetion and Fuel System forum.
I'll wait a bit so you'll have a chance to check back here, then move this thread to Fuel Injection, Carburetion and Fuel System. It's not necessarily that this is the wrong forum, but it just deserves the most suitable forum since it involves technical discussion of fuel systems.
[FONT=Comic Sans MS][COLOR=black][COLOR=navy]Scott[/COLOR][/COLOR][/FONT]
Rusty, what book are you refering too ? I have found lots of stuff on methanol racing, most of it suggesting the 6 or 7 to 1 fuel ratio you mentioned. I have found nothing ( at least not yet ) on ethanol.
pullScott, although I didn't try it, on my other thread, my computer shows a 'closed' with a little padlock next to it where you would normally hit the reply button. Is there a differance between closed and locked ? Anyway, I hoping you'll leave the thread here in the liquid section. I'd like to get away from the discussion of the nuts and bolts stuff- I think the 750 Holley will mix anything I ask it too. I am far more interested in the physical properties of the fuel itself, and how that might affect the way the truck runs. I think the nuts and bolts part is already solved. DF
DF, you're right about it being locked. I have a hard time seeing those little paddlocks! I checked the second page of that thread and indeed it was locked by the admin.
Okay, it stays here. Let's try to keep the topic focused on fluid chemistry and fuels. Even though this forum is chartered to discuss oil and lubrication, I like to stretch it a bit to include most all automotive fluids. It seems to me that the folks who have the knowledge and technical information about oil are also better informed about fuels and fuel additives.
I don't know how that last alcohol thread got so FUBBAR. It almost seems like it got started as a general converstation topic and moved here. Either that or I was off skylarking...
[FONT=Comic Sans MS][COLOR=black][COLOR=navy]Scott[/COLOR][/COLOR][/FONT]
Ethanol allows motors to run cooler than the same motor on gas. Virtually no junk in ethanol, no soot, ash and other dirty stuff. If you get a big jug of gas(30 or so gallons) the stuff looks black, ethanol is clear. A proper conversion to ethanol is like 98% of a gas motor. AS for economy, if your running 12-1 comp VS 8-1 on gas your getting like 1/3 more bang which would probaly level out the cost of a higher fuel ratio?? . It's not so much on the performance things but more envronmental, a motor running on ethanol is producing virtually no hydrocarbons, particulate, has reduced Nox from the cooler burning fuel, valve life is extended, and lots more..The added performance is a cherry on top the cake when all the other benefits are added up. All a man needs is a huge pile of dead plants and stuff to make the stuff along with some equipment. When ethanol comes out in Canada I'm gonna be on it like a fat man eating a piece of cheese cake after I read this info I found on it years ago. Too bad for politics though... I'll stop now thanks for the chance to discuss, it's rare to hear people actually discuss alternative fuel without some one saying gas is cheaper or the government is doing this and that and blah blah blah.
The book I am referring to is "Super Tuning and Modifying Holley Carburetors" by Dave Emanuel. It has a section on page 83 that deals with alcohol. Their focus is more for racing, though. They recommend drilling fuel passages out to the maximum size, and other things like that. For the street, below 400hp, it says a single 4barrel should deliver all the fuel you'll need. I said 600cfm because it'd be harder to lean it out with that by flowing more air than the fuel passages could handle. I believe they are talking about pure alcohol in this book, and as such E85 may work better.
Rusty, the book from Dave E. is probably refering to Methanol. Most folks are when they are talking about alcohol as an engine fuel. It is unfortunate when discussing alcohol that what seems to be the best alcohol for an engine (ethyl ) is also the kind that folks drink. Ethyl being drinkin' alky has also attracted lots of gov't attention and for a long time ethanol fuels had to pay beverage taxes. thus racers used undrinkable wood alky for their engines, and avoided gov't attention and taxes. now that the gov't seems to realize that fuel alky and beverage alky are used very differantly, perhaps ethanol fuels will become more available. I believe ethanol, with 2/3rds the btus of gasoline is easier than methanol, with 1/2 of the btus of gas, to carry around. The charts on the 'journey to forever' page linked above show that ethyl has 2/3rds the btus and would mix at about 9 to 1. the reid vapour pressure of ethyl alcohol also is a concern. I think it is somewhere around 3psi. Gasoline, depending on what season it is blended for much higher (11-15 ?). So cold starts could be a problem. The vapour pressure issue is why I'm thinking that the E85 fuel might be a very good choice. DF, at his Dad's
The 4.0L in my 2003 Ranger is a "Flex Fuel" engine. Meaning it will run ethonal spiked gas with no problem. This leads me to suspect if your engine is not a "Flex Fuel" engine, there may be some problem related to running the alcohol.
Very cool topic. I'm relatively new around here, and I just happened to stumble across this post.
Regarding ethanol as a fuel, it definitely burns cleaner and has a higher octane rating that gasoline does. The octane rating of pure ethanol varies from around 107 to anywhere near 115. The higher octane rating allows you to increase the compression ratio without knock to create a power output close to that of a gasoline engine. While power will be close to its gasoline burning brother, emissions will be substantially lower. I'll post the combustion equations to show the reactions if anyone's interested.
In order to run on ethanol, the air-fuel mixture needs to be around 9:1 as opposed to the average of about 12:1 for a gasoline engine. Ethanol can even be used as a fuel in diesel engines.....but the autoignite temperature is substantially higher, requiring the engine to be started on diesel then switched over to ethanol once the engine reaches normal operating temperatures.
Regarding pre-ignition AKA knock....... High octane fuels do not vaporize as well as lower octane fuels do. This lack of vaporization causes much of the mixture to remain as a liquid instead of the dry vapor necessary for efficient combustion. Since there is less fuel in the fuel/air mixture, the mixture is often way too lean....causing detonation and internal damage. So in the case of higher octane fuels, it is the octane rating iteself that often causes the lean mixture, resulting in detonation. This is the reason you need to richen the mixture when burning ethanol.
A full ethanol conversion has been done many times now and is fairly simple to do whether running a carb or EFI. Corrosion can be a problem when burning ethanol....but as long as the engine is run daily, it shouldn't be a problem.
Looking forward to more discussion!!
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I'd like to try to clarify the basic reason that ethanol causes a power and/or mileage loss. That is because its "specific heat", or energy released per gallon when completely oxidized, is much less than that of gasoline. It is true that it has a higher octane rating allowing a higher compression ratio so that more of that heat can do work, but you cannot usually overcome the deficit you began with. And without substantial modification, most existing engines will lose output by a factor proportional to the percent of ethanol.
You are incorrect on a number of points. An engine burning ethanol gets about the same fuel economy as an engine burning gasoline, and the ethanol engine will actually get BETTER mileage compared to a gasoline engine when under heavy loads such as towing. The increase in compression over the gasoline burning engine is what makes this true. All gasoline engines use what's called an Otto cycle. The Otto cycle is more efficient than the diesel cycle when comparing the two using the exact same compression ratio. The increase in compression of the diesel cycle over the Otto cycle is what makes diesel engines more efficient. Anytime you can increase the compression ratio of an Otto cycle engine, you are actually increasing its efficiency.
Your definition of specific heat is also incorrect. Specific heat can be simply defined as the amount of heat required to raise a unit mass (or mole) of a substance by one degree in temperature. The specific heat of a substance does not define the energy available in a combustion process. You're mistaking specific heat for a heat energy value.
And you say most engines burning ethanol will lose power output when compared to a gasoline burning engine......that may be true if making the conversion to ethanol without any modifications but if one takes the time do increase the compression ratio as well as make other changes the power potential equals that of a gasoline engine. Don't take my word for it. Check the link:
Originally posted by Rat wagon It's not so much on the performance things but more envronmental, a motor running on ethanol is producing virtually no hydrocarbons, particulate, has reduced Nox from the cooler burning fuel, valve life is extended, and lots more..The added performance is a cherry on top the cake when all the other benefits are added up.
The problem is that it takes more units of energy to produce an alcohol fuel than you get from the process. It may burn clean, but it isn't clean to make. Biodiesel, on the other hand, takes about 3 units of energy to make 10 units of fuel.
I am familiar with the Otto cycle and, as you are aware, the theoretical percent of energy that can be converted to work does depend on the compression ratio. I apologize for mistating the terms, but the fact remains, if you start with only 60% of the available energy you cannot make it up by increasing your conversion efficiency by 5%. And I don't think raising the compression ratio on my daily driver is likely to be cost effective.
I don't say this to dampen anyone's enthusiasm for improvements in our trucks, or to use more Americans and American products. I just think that we cannot candy coat ethanol's negatives or we will have another fiasco like the EV, where basically the CARB tried to overrule the laws of physics.
Unfortunately for the ethanol industry, petroleum is literally like "manna from heaven" in that it is so cheap. Even today, much of the cost of gasoline is tax. How will our politicians replace that?
Near term, using less petroleum through higher efficiency and hybrid engines or finding new sources (shale oil, coal conversion, etc.) seem better than replacing it. And frankly, if we do decide we should use less, the government should probably tax it instead of mandating or subsidizing the "best " alternative. That is called market planning and didn't work too well for the Russians!
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