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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / May 2005Alcohol as a fuel
I went on business trip the Brasil last week. Pretty much all the gas stations sold alcohol as a fuel and at most if not all pumps. (I didn't know enough Portuguese to be able to ascertain if it's 100% alcohol or a mix with gas). The price was about 1/2 that of gas, tho at $3.50 a gallon that's no bargain. What's the advantage or otherwise of alcohol as a fuel for street cars? The Taxi I drove in seemed to run fine on it. I presume it's ethanol. There is a small number of ethanol ready vehicles in the US, but by far the minority of what's generally available. I haven't seen any ethanol or alcohol for sale in Tennessee or the surrounding states. As a renewal and green energy source, I wonder why it is not more widely available in the US? The oil companies sell both regular gas and alcohol at the same pumps, so they get their money either way. Struck me as odd that an emerging economy is years ahead of the US. JP  SignatureJP White mailto:jpwhite3@bellsouth.net I lived in Brasil in the 70's when the alcohol project was beginning. The advantage was that, since Brasil had essentially no major fossil petroleum deposits at that time and that gasoline was an issue for a country as populous as Brasil, alcohol from fermentation could be applied as a fuel. We lived under a military dictatorship in those days, and this program was championed as it probably could not have been in a democratic society. There was plenty of sugar, cassava, etc from which ethyl alcohol could be made. Cars were developed that would run on 100% alcohol. Now, the table has turned a bit. The producers may have better markets for their raw materials than to convert it to motor fuel. A lot of what you see is a blend of alcohol with gasoline but there may still be some remnants of the old program around. I met with a friend and colleague from PetroBras in January, and he confirmed that the old 100% alcohol replacement for gasoline is essentially 'history'. I guess no one has heard of gas-o-hol? Its in our marine gas pumps and has been for quite a while. A big ta-do over in-tank water and gas not mixing versus alcohol and in-tank water being able to mix is a big deal on boats . Last time I checked it was at 10%. It gives folks issues with fuel line materials in that it is shortens the life of fuel lines not constructed to handle the alcohol content. Just my .02 > I went on business trip the Brasil last week. Pretty much all the gas > stations sold alcohol as a fuel and at most if not all pumps. (I didn't [quoted text clipped - 14 lines] > > JP The only advantages are that 1) it has a very high octane, and 2) it is renewable. It's disadvantages are that it contains only half the energy content per gallon compared to gasoline, so with the same size tank, the range is cut almost in half. I say almost because if the engine is made specifically for ethanol one could raise CR a bit and gain some thermal efficiency. Its emissions are a mixed bag. Apparently less CO, but still lots of greenhouse gases, and more complex hydrocarbons in emissions. It can negatively affect fuel system components in fuel system if that system has not been designed specifically for ethanol. Worst, in my opinion, is that today most ethanol is made by processing (heating) with natural gas or petroleum. So it is unclear how much petroleum we are actually saving. If the ethanol industry would convert to none-fossil-fuel process, that would be something else. >> I went on business trip the Brasil last week. Pretty much all the gas >> stations sold alcohol as a fuel and at most if not all pumps. (I didn't [quoted text clipped - 17 lines] > The only advantages are that 1) it has a very high octane, and 2) it is > renewable. <snip> Higher octane = lower combustion temperature Except in a car that requires this, when is it an advantage? > Higher octane = lower combustion temperature Incorrect. Octane has nothing to do with combustion temperature, octane rating is a measure of how easily the fuel self-ignites at high temperature. High octane -> resistance to self ignition. > Except in a car that requires this, when is it an advantage? The higher you make any engine's compression ratio, the more thermodynamically efficient the engine is. High octane allows a spark-ignition engine to operate at a higher compression ratio without damaging detonation, so higher octane allows designers to build more efficient engines. But you're right in that if you take a low-compression engine and feed it high-octane fuel, you gain nothing. >> Higher octane = lower combustion temperature > [quoted text clipped - 12 lines] > But you're right in that if you take a low-compression engine and feed it > high-octane fuel, you gain nothing. You're right. I meant to say higher octane = higher combustion temperature, which while still not technically correct, you've made the point of what I was getting at. Thanks for the clarification. I should have also said, "except in an *engine* that requires this ..." > The only advantages are that 1) it has a very high octane, and 2) it is > renewable. [quoted text clipped - 4 lines] > specifically for ethanol one could raise CR a bit and gain some thermal > efficiency. Actually it contains about 2/3 as much energy per gallon as gasoline (see http://www.chevron.com/prodserv/fuels/bulletin/oxy-fuel/enrgycon.shtml ). http://www.bioproducts-bioenergy.gov/pdfpresentations/Net%20Energy%20Balance%20o f%20Corn%20Ethanol_Shapouri.ppt Ed Basically the big scam now is they are adding 'alcohol' to our fuel because it is 'politically' correct and ups their profit margin to the extreme! When they add that 5 or 10% 'alcohol', the gas mileage on most vehicles drops by 30 to 50% so by making farmers feel good, they are making us fill up twice as often. Just one of my Jeeps for instance gets well over 350 miles plus on a tank of 'real' gasoline. Add alcohol and I am out of gas at 200 - 225 miles. Off road I don't get 100 miles with that mix vs an easy 200 miles running gas. It is a total rip off scam. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's > I went on business trip the Brasil last week. Pretty much all the gas > stations sold alcohol as a fuel and at most if not all pumps. (I didn't [quoted text clipped - 18 lines] > JP White > mailto:jpwhite3@bellsouth.net > Basically the big scam now is they are adding 'alcohol' to our fuel > because it is 'politically' correct and ups their profit margin to the [quoted text clipped - 3 lines] > drops by 30 to 50% so by making farmers feel good, they are making us > fill up twice as often. I think you are wrong when you include "most" engines in your statement. Do you really think it is reasonable to claim a 30% to 50% reduction based on replacing 5% or 10% of the gasoline with alcohol? Even if the alcohol was inert, you should get a 30% reduction. Are you talking about older, carbureted engines? They might suffer more than modern vehicles For a modern fuel injected engine the decrease should be less than 3%. Maybe even less if your engine has a knock sensor and can advance the timing. See http://www.chevron.com/prodserv/fuels/bulletin/oxy-fuel/cfuelecn.shtml . You might also want to read: http://www.epa.gov/orcdizux/consumer/fuels/altfuels/420f00035.pdf > Just one of my Jeeps for instance gets well over 350 miles plus on a > tank of 'real' gasoline. Add alcohol and I am out of gas at 200 - 225 > miles. Off road I don't get 100 miles with that mix vs an easy 200 > miles running gas. I think your Jeep could use a tune-up. What percentage alcohol? How carefully did you make your measurements? Given you hostility towards alcohol, did you only try it once? A 50% reduction in mileage is unbelievable unless there is something drastically wrong with your vehicle. At the most you shouldn't see more than a 10% reduction (this assumes you get no energy from alcohol, which isn't likely). Is your Jeep even qualified to run on a gasoline / alcohol mix? I had a couple of older cars that couldn't stand gasahol (ate the fuel lines). > It is a total rip off scam. I think calling it a "total rip off scam" is over the top. Is it any worse than sending the money to the Saudis? If we could reduce the uses of oil by 10% by substituting alcohol for gasoline, and the total amount of the "mixture" needed increased by 3% (becasue of the reduction in fuel economy), we would still be importing significaantly less oil (at least 7% less). A 7% reduction in oil imports would lead to lower prices. Ed Mike Romain <romainm@sympatico.ca> wrote in news:4277800A.1701D2F1 @sympatico.ca: > Basically the big scam now is they are adding 'alcohol' to our fuel > because it is 'politically' correct and ups their profit margin to the [quoted text clipped - 37 lines] >> JP White >> mailto:jpwhite3@bellsouth.net you are full of it. We have been running 10%ethanol mix for years here. the fuel milage drop is only directly porportaniol to the amount of the mix. so 10% ethanol will drop the milage the roughly 40% of the 10% that is not gas. usually 1/2 mpg or so. (example- if you get 20 mpg with gas then you will get 19.2 with ethanol) the E85 specific ones get better that this because the eng is optimized for the ethanol. If you are getting anything diff than this it is because your area has some specific law making your fuel different for emissions purposes. Here in the midwest we have run gasahol for over 15 years so I have checked it over and over again. And a tax reduction is NOT a subsidy. Letting you keep some of your own money is not a subsidy. It is a inscentive. There is a big difference. KB ThunderSnake #9 Warn once, shoot twice 460 in the pkup, 460 on the stand for another pkup and one in the shed for a fun project to yet be decided on > Basically the big scam now is they are adding 'alcohol' to our fuel > because it is 'politically' correct and ups their profit margin to the [quoted text clipped - 12 lines] > > Mike While I am certainly no ethanol booster, I do not notice anything like the drop Mike sees. I see less than a 5% drop compared to regular. My Neon has a knock sensor, and when I use regular rather than premium I suspect the spark retards just a bit. I interpret the fact that I do not notice the predicted 5-7 percent drop to the fact that the ethanol has much higher octane, even higher than the premium I occasionally use, and so the spark is probably advancing to a better, more efficient setting. > > Just one of my Jeeps for instance gets well over 350 miles plus on a > > tank of 'real' gasoline. Add alcohol and I am out of gas at 200 - 225 > > miles. Off road I don't get 100 miles with that mix vs an easy 200 > > miles running gas. > While I am certainly no ethanol booster, I do not notice anything like > the drop Mike sees. Mike "sees" lots of fascinating stuff that isn't real. > > > Just one of my Jeeps for instance gets well over 350 miles plus on a > > > tank of 'real' gasoline. Add alcohol and I am out of gas at 200 - 225 [quoted text clipped - 5 lines] > > Mike "sees" lots of fascinating stuff that isn't real. Ahh.... to have lived such a sheltered life, must be nice Daniel.... Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's > > > Just one of my Jeeps for instance gets well over 350 miles plus on a > > > tank of 'real' gasoline. Add alcohol and I am out of gas at 200 - 225 [quoted text clipped - 5 lines] > > Mike "sees" lots of fascinating stuff that isn't real. This *can* be a lot of fun! > Basically the big scam now is they are adding 'alcohol' to our fuel > because it is 'politically' correct and ups their profit margin to the [quoted text clipped - 3 lines] > drops by 30 to 50% so by making farmers feel good, they are making us > fill up twice as often. I don't think so. This statements suggests that it's author knows nothing about an internal combustion engine. As a high performance engine builder, not only do I know better, I have personally seen the advantage of running ethanol over gasoline. Cylinder walls will tell a heck of a story! > Just one of my Jeeps for instance gets well over 350 miles plus on a > tank of 'real' gasoline. Add alcohol and I am out of gas at 200 - 225 > miles. Off road I don't get 100 miles with that mix vs an easy 200 > miles running gas. This jeep must be in a serious need of a tune up or the author is paid by an oil company to make this claim. If ethanol is so bad and so inefficient, then why does a blown ethanol alcohol dragster blow the doors off a blown gas dragster? How about the IRL switching from methanol to ethanol in the 2006 racing season? Hummmm, the serious racers seem to prefer alcohol over gasoline...wonder why? > It is a total rip off scam. And the oil companies aren't organizing a total rip-off scam? Then why can I buy a barrel of fuel grade, distilled and ready to burn ethanol for $44 a barrel while a barrel of unrefined and unprocessed crude is selling at $50+ a barrel? You can call up any oil company represantive and they will blame the current price of gas on the lack of refineries. But if that was the case, then there should be a surpluss of crude on the market and thus lower crude prices since the refineries (supposedly) can't refine it as fast as the crude is pumped. But that doesn't seem to be the case when you see how high crude is selling on the stock exchange. If you go to yahoo finance and bring up the 2yr stock quotes graph of BP, Shell Canada, Chevron/Texaco, Exxon Mobile, Unocal, etc, you will see the real rip off scam in action and who is behind it. The point is, these companies and OPEC have organized a monopoly and have artificially raised the crude oil prices and thus gouging us at the pump. Heck, I can even fill-up my diesel with jet-fuel (kerosene) at the airport cheaper than I can buy #2 diesel and the price of Jet-A hasn't changed in four years! They must still be making money on jet-fuel or it's price would have gone up as well. Mgrant > Mike > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 [quoted text clipped - 22 lines] > > JP White > > mailto:jpwhite3@bellsouth.net > I don't think so. This statements suggests that it's author knows > nothing about an internal combustion engine. As a high performance > engine builder, not only do I know better, I have personally seen the > advantage of running ethanol over gasoline. Cylinder walls will tell a > heck of a story! Ok, now we have a pro on-hand. Let me go in that direction instead of political whining. > And the oil companies aren't organizing a total rip-off scam? Then why > can I buy a barrel of fuel grade, distilled and ready to burn ethanol > for $44 a barrel while a barrel of unrefined and unprocessed crude is > selling at $50+ a barrel? Is that true? Where can I buy one of those barrels? Will they ship to my location for $44 or do I have to drive to Kuwait or Caracas to pick it up? If this is true then the answer is very obvious, we just buy from that $44 distributor. I'm not opposed to accepting how the whole oil-monopoly works but when one individual makes such an assertation, well, then the real meat of the story has to logically follow. You can call up any oil company represantive > and they will blame the current price of gas on the lack of refineries. > But if that was the case, I'm with you on this. The "lack of refineries" has only made it into the rant within the past couple of months. For my part, spokesmen tossing out such statements doesn't prove there is or isn't a lack of refineries...just like the power grid problems that occured in the Midwest a couple of years ago. Sure...more of either...and improved management of that aspect can be called out on even the best of days but it never is. We only seem to do it at crisis time. I don't know how "lack of refineries" all of a sudden translates into 30% increases in retail gas from January to March. > gouging us at the pump. Heck, I can even fill-up my diesel with > jet-fuel (kerosene) at the airport cheaper than I can buy #2 diesel and > the price of Jet-A hasn't changed in four years! They must still be > making money on jet-fuel or it's price would have gone up as well. > > Mgrant Hmmm....I'd be careful there. That mentality sent down a plane at the end of the runway here in San Juan a couple months ago killing a few people. The initial investigation suggests that the pilot was trying to out-think the fueler guys for a better price. I wouldn't want this to become "advice". Bill The $44 a barrel for ethanol is a the current trading quote, well a month old now, for fuel grade ethanol in the midwest. http://www.purchasing.com/article/CA514854.html?industryid=2148 I wished I knew the quoted supplier as well, I would have several barrels sitting in my shop if I did. On the last comment I stated, I think you missed the point I was trying to make. I was referring to filling up my diesel pickup, not a turbine powered aircraft, with Jet-A cheaper than I can fill it with #2 diesel at the local Exxon station ...grin :). I'm sure someone, who thinks they know what they are talking about, will reply that burning Jet fuel in my Cummins will ruin my engine, which would be a bogus comment that I won't even bother responding to. I figured that I would nip that comment at the bud before it's even posted. :) Mgrant > The $44 a barrel for ethanol is a the current trading quote, well a > month old now, for fuel grade ethanol in the midwest. > http://www.purchasing.com/article/CA514854.html?industryid=2148 > I wished I knew the quoted supplier as well, I would have several > barrels sitting in my shop if I did. As would we all. > On the last comment I stated, I think you missed the point I was trying > to make. I was referring to filling up my diesel pickup, not a turbine [quoted text clipped - 4 lines] > I won't even bother responding to. I figured that I would nip that > comment at the bud before it's even posted. :) Ok, fair enough. My fear is the folks that would choose to outthink their engine for a few cents on the gallon wouldn't be, en masse, sophisticated enough to make these determinations. To wit, my example of a supposedly skilled and instructed pilot guy who takes his plane (or hoped to) thousands of feet into the air because he thought he was smarter than the oil industry. It didn't work in his case. So yeah, I'll also consider that idea nipped. Its difficult to comment on the situation without waxing political or stepping on toes, neither of which I intend to do. But in reading these threads the one thing that keeps coming up is the net efficiency of processing corn or whatever into fuel. I'm still unclear how that works. It may take x-amount of petro dollars to do this, and the calculated result seems inefficient but the bottom line is that we are trying to get AWAY from thinking in terms of petro-dollars. In the US we have tens of thousands of square miles that are suited for not much more than growing corn. We don't have enough oil production to meet our needs and have to rely on a bunch of turbanned throat slitters. So what if we use twice as much corn by textbook efficiency standards to fuel our needs? We got corn! The implication is that we need oil to make this conversion. Well, the way I see it, is that if we intend to power our vehicles and power plants with corncobs then we logically would be able to power the corncob processing factory out of the same cobs. Inefficent? Compared to wars, etc? I'll leave that to the political pundits. Growing corn (just an example) and developing technology around that fuel makes a lot of sense to me. If your 2010 model Vega isn't as spunky as your 2004 Hawg SUV, sooo what? Beats the alternative of where we seem to be headed. Just thinking out loud. -ex Since were thinking in terms of the inefficiency in where were headed, I might add a comment that seems to make this thought very relavent to where I live. I reside in north Idaho and this is very redneck country, so you can imagine huge engined gas guzzlers sitting on top of 40" tires. I'm not against jacked up 4x4s as a hobby, but what puzzles me is that these guys will sacrafice their family's financial well-being so they can keep their $40,000 4x4 parked outside of their $5000 trailerhouse. They feed it $2.50/gal gas so they can look cool in their daily commute to work and on the weekends they will drive, under the influence, through the woods and see if they can get it stuck in a pristine raparian area on public lands. If they would only get an economical car to commute with, they would be able to raise their kids in a nice home that they would own, they can start a college fund for them, and not have to engage in brewing meth in their bathtubs in order to pay for the truck. The end result would be a fully functional family instead of a dysfunctional one that ends in a divorse, which would lead to eventual reposession of the gas guzzling 4x4 anyway. Mgrant > > The $44 a barrel for ethanol is a the current trading quote, well a > > month old now, for fuel grade ethanol in the midwest. [quoted text clipped - 23 lines] > > Its difficult to comment on the situation without waxing political or > stepping on toes, neither of which I intend to do. But in reading these > threads the one thing that keeps coming up is the net efficiency of [quoted text clipped - 13 lines] > > Inefficent? Compared to wars, etc? I'll leave that to the political > pundits. Growing corn (just an example) and developing technology > around that fuel makes a lot of sense to me. If your 2010 model Vega > isn't as spunky as your 2004 Hawg SUV, sooo what? Beats the alternative > of where we seem to be headed. > > Just thinking out loud. > > -ex > Inefficent? Compared to wars, etc? I'll leave that to the political > pundits. Growing corn (just an example) and developing technology [quoted text clipped - 3 lines] > > Just thinking out loud. Boy, I'm with you. Maybe I am an old fuddy duddy (I am past 65, though I have a vintage racing car in my garage that I run a number of times each year). I read a review of a number of cars the other day. The 0=60 times ran mostly in the 7-8 second range. One was pinged with inadequate performance 'cause its time was 10 seconds. Gee, my current Neon R/T is the only car I ever had that could do it in under 10. I never considered my old Barracuda (small block V8) inadequate performance (it took a little under 11). How much performance do we need for street driving? Only concern I have for using biomass fuels to process biomass is the CO2 emissions. To me any alternate energy policy does need to consider greenhouse gases. >Only concern I have for using biomass fuels to process biomass is the >CO2 emissions. To me any alternate energy policy does need to consider >greenhouse gases. Biomass fuel is, pretty much by definition, CO2 neutral. All the CO2 that gets produced while it burns is the *same* CO2 that the plant took out of the air to store in its biomass in the first place. Jasper > Biomass fuel is, pretty much by definition, CO2 neutral. All the CO2 > that gets produced while it burns is the *same* CO2 that the plant took > out of the air to store in its biomass in the first place. Jolly good, but once it's been released, it's no longer sequestered -- which means biomass fuel is NOT "CO2 neutral". > > Biomass fuel is, pretty much by definition, CO2 neutral. All the CO2 > > that gets produced while it burns is the *same* CO2 that the plant took > > out of the air to store in its biomass in the first place. > > Jolly good, but once it's been released, it's no longer sequestered -- > which means biomass fuel is NOT "CO2 neutral". If you grew something (corn, sugar cane, beets, whatever) to produce alcohol, you removed CO2 from the atmosphere. When you "burn" the alcohol, you recreate the CO2, but then you need to re-remove it to make more alcohol. Seems to me this is pretty much "CO2 neutral." Ed >> Biomass fuel is, pretty much by definition, CO2 neutral. All the CO2 >> that gets produced while it burns is the *same* CO2 that the plant took >> out of the air to store in its biomass in the first place. > >Jolly good, but once it's been released, it's no longer sequestered -- >which means biomass fuel is NOT "CO2 neutral". what exactly do you think would happen to the biomass if it *wasn't* processed into fuel? Apart from biomass which sinks to the bottom of the ocean (and nobody yet is talking about plankton-diesel), *all* CO2 that gets sequestered in biomass eventually finds its way back into the air. Jasper > >> Biomass fuel is, pretty much by definition, CO2 neutral. All the CO2 > >> that gets produced while it burns is the *same* CO2 that the plant took [quoted text clipped - 7 lines] > ocean (and nobody yet is talking about plankton-diesel), *all* CO2 that > gets sequestered in biomass eventually finds its way back into the air. Limestone, coal, etc seems like very long term storage... Ed >>what exactly do you think would happen to the biomass if it *wasn't* >>processed into fuel? Apart from biomass which sinks to the bottom of the [quoted text clipped - 4 lines] > > Ed As long as we don't burn it for fuel. That brings it back into air. > The $44 a barrel for ethanol is a the current trading quote, well a > month old now, for fuel grade ethanol in the midwest. [quoted text clipped - 12 lines] > > Mgrant I forget which jet fuel is which, but isn't one of them (the one the Navy uses) essentially kerosene. Isn't one of the Diesel road fuels essentially kerosene. If the engine will run that Diesel fuel, wouldn't it run the jet fuel (maybe it is B) that is essentially kerosene without damage? We've ran Jet-A in the engine fuel tanks of the helicopter refueler trucks for years without any engine damage at all. Essentially, it is highly filtered #1 diesel (kerosene). Our fuel supplier reported that #1 diesel and Jet A came from the same exact pipeline into their tank farm. The only difference is that after Jet A leaves the tank farm, it is highly filtered and data logged to the FAA each time it is transfered where #1 is not. Since Jet A is dryer, we add a qt lubricant to the tank to help lubricate the injector pumps. I've heard that the military runs both JP8 (Jet A) and JP4 (kerosene and avgas mix known as Jet B) in their diesel Humvees ever since their introduction, but I think I would prefer to burn Jet A over Jet B in my diesel. > We've ran Jet-A in the engine fuel tanks of the helicopter refueler > trucks for years without any engine damage at all. Essentially, it is [quoted text clipped - 7 lines] > Jet B) in their diesel Humvees ever since their introduction, but I > think I would prefer to burn Jet A over Jet B in my diesel. I understand that jet fuel contains a fungicide, but gee, I'd think that would be desireable in Diesel fuel also. Remember hearing about the bug that can live and thrive in jet fuel- I suspect it could also live in Diesel, since they are so close. > > Basically the big scam now is they are adding 'alcohol' to our fuel > > because it is 'politically' correct and ups their profit margin to [quoted text clipped - 20 lines] > This jeep must be in a serious need of a tune up or the author is paid > by an oil company to make this claim. Nope on both accounts. Old Jeeps just plain don't like any alcohol of any type. The owners manual even warns only to use it in an emergency to get to real fuel and that performance may degrade. My CJ7 258 I6 goes like a scalded cat. It pulls up to 50 mph in 2nd, 75 in 3rd, 4th will bury the speedometer and I have no freaking urge to find out how fast 5th will go.... As for a tune up, here are my recent emission numbers. No computer running anything and no catalytic converter. (not needed for this utility vehicle) On the ASM 2525 dyno test I got 589 NOx and 16 ppm HC and 0.11% CO. I also get a sweet 23 US mpg running loaded with gear at 70 mph with 91 octane 'gasoline'. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's > This jeep must be in a serious need of a tune up or the author is paid > by an oil company to make this claim. If ethanol is so bad and so > inefficient, then why does a blown ethanol alcohol dragster blow the > doors off a blown gas dragster? How about the IRL switching from > methanol to ethanol in the 2006 racing season? Hummmm, the serious > racers seem to prefer alcohol over gasoline...wonder why? Actually, most racing cars using alcohol use methanol rather than ethanol, but that is a small difference. Two reasons alcohol is preferred in racing cars. First, its octane is very high, allowing us to run very high compression ratio. Second, in many sanctioning bodies, "gas" cannot contain boosters like nitro-methane, a very strong oxygen supplement, while alky classes can. However, I agree that the loss of hp in the 30 - 50% range is fiction. Without raising the CR of the engine, one does loose a little hp. How much depends on whether engine has a knock sensor that will advance spark a bit on higher octane fuels. >However, I agree that the loss of hp in the 30 - 50% range is fiction. He didn't say loss of HP, he said loss of mileage. If I read the tables correctly, a gallon of alcohol contains less stored energy than gasoline, so that's the right way to bet. > Without raising the CR of the engine, one does loose a little hp. How >much depends on whether engine has a knock sensor that will advance >spark a bit on higher octane fuels. Knock sensors never advance spark timing for higher octane fuels; all they do is retard the timing if the octane is too low to support the CR. Since that's never more efficient with a given fuel than just having the right CR and the right timing, you don't *want* the knock sensor to be used in that way. Jasper > >However, I agree that the loss of hp in the 30 - 50% range is fiction. > > He didn't say loss of HP, he said loss of mileage. If I read the tables > correctly, a gallon of alcohol contains less stored energy than gasoline, > so that's the right way to bet. Power and mileage are simply different ways of looking at the amount of work done per volume unit of fuel. Ethanol contains less energy per volume unit than gasoline, which means both less power AND less mileage. However, Mike R's claim is that his loss in mileage is *an order of magnitude* greater than the amount by which gasohol contains less energy than gasoline, and that is simply not realistic. > Knock sensors never advance spark timing for higher octane fuels; all they > do is retard the timing if the octane is too low to support the CR. That's flatly wrong; there are plenty of systems calibrated so as never to give any benefit with higher than a given octane (e.g. 87 regular at sea level), but there are also plenty of systems calibrated so as to dial in more spark advance if the fuel will support it without pinging. > >However, I agree that the loss of hp in the 30 - 50% range is fiction. > > He didn't say loss of HP, he said loss of mileage. If I read the tables > correctly, a gallon of alcohol contains less stored energy than gasoline, > so that's the right way to bet. But not 30 to 50% less. Alcohol has about 66% as much energy per gallon as gasoline. From http://www.chevron.com/products/prodserv/fuels/bulletin/motorgas/8_q-a/#3 "3. Will oxygenated gasoline perform as well as conventional gasoline in my vehicle? Oxygenated gasoline will perform as well in modern vehicles with engine control systems that adjust the air-fuel ratio. Oxygenated gasoline may cause some driveability problems in carbureted cars and fuel injected cars without engine control systems because they result in an air-fuel mixture that is more fuel lean. Oxygenated gasoline reduces fuel economy, on average, by 2 to 3 percent. The odor of gasoline oxygenated with MTBE or the other ethers differs from that of conventional gasoline." > > Without raising the CR of the engine, one does loose a little hp. How > >much depends on whether engine has a knock sensor that will advance [quoted text clipped - 5 lines] > CR and the right timing, you don't *want* the knock sensor to be used in > that way. According to Ford, the PCM in a 1997 Expedition (and other years as well probably), would take advantage of higher octane fuel by advancing the timing. I am guessing that the computer advanced the timing until kock was detected and then held it there for some duration (trip, tank, soemthing) and then repeated the process. I tried premium in my '97 Expedition and the mileage did improve, but only slightly (measurement over thousands of miles) and was not worht the added cost of premium fuel. Other interesting references: http://www.chevron.com/products/prodserv/fuels/bulletin/motorgas/4_oxygenated-ga soline/pg2.asp Ed > "3. Will oxygenated gasoline perform as well as conventional > gasoline in my vehicle? > Oxygenated gasoline will perform as well in modern vehicles > with engine control systems that adjust the air-fuel ratio. False. Oxygenated fuel contains less energy per volume unit than unadulterated gasoline. Correct AFR is nice, but does not change the fact that you get less power on oxygenated fuel, and you burn more of it to do the same work...simply because oxygenated fuel contains less energy. >>"3. Will oxygenated gasoline perform as well as conventional >>gasoline in my vehicle? > >>Oxygenated gasoline will perform as well in modern vehicles >>with engine control systems that adjust the air-fuel ratio. Correct. > False. Oxygenated fuel contains less energy per volume unit than > unadulterated gasoline. Correct AFR is nice, but does not change the fact > that you get less power on oxygenated fuel, and you burn more of it to do > the same work...simply because oxygenated fuel contains less energy. Flatly Incorrect. Power is determined by the engine's ability to fully utilize the AIR that it inducts not the fuel. Since both ethanol and methanol have less energy per volume of fuel, one just adds more fuel until all of the oxygen is consumed. Remember the goal of performance is power. We in principle just keep adding fuel until all the oxygen is consumed. Let's use a 10% rich mixture of both ethanol, methanol vs. gasoline. For one Kg of air, one needs: Ethanol Methanol Gasoline density kg/L .794 .796 .745 stoich A/F 9:1 6.45:1 14.6:1 10% Rich 8.1:1 5.81:1 13.14:1 LHV MJ/kg 26.68 19.95 43 LHV/(a/f) 3.29 3.44 3.2 (MJ/kg-air) The Lower Heating Value (MegaJoules/kg) divided by target A/F gives you the actual energy supplied for each kg of air inducted. By this simple analysis Methanol wins by a noticeable margin (7%), followed by ethanol (3%) and then gasoline. This is without any changes in CR, vol. eff., etc. Let's look at other properties of alcohols and how they affect performance. Alcohols have a noticeably higher latent heat of vaporization. Methanol is best here. This means there will be significant charge cooling either during induction or early in the compression stroke. The net result is generally an increase in volumetric efficiency and a cooler charge at the time of ignition. The benefit of increased vol. eff. is obvious. The cooler charge leads to reduced heat transfer losses and slightly higher net output (higher thermal efficiency). So far all these benefits come with NO change in compression ratio. But, alcohols also have a higher octane rating which can be taken advantage of by increasing compression ratio which would then lead to even higher output. These reasons are why alcohols are favored for performance. All things being optimized one can always get more power out of an alcohol fuel than gasoline. The downside being you have to carry more volume of fuel. But what about fuel economy, where this thread started. The goal in fuel economy is to fully utilize the FUEL. Here, the energy per unit volume does factor in and indeed alcohols don't fair so well. As has been stated they don't have as many MJ/L. Again using the numbers from above. I can calculate the relative energy/unit volume of fuel as: Volumetric energy = LHV*density MeOH 15.8 MJ/Liter EtOH 20.8 MJ/Liter x 0.1 = 2.08 Gasoline ~31.3 MJ/Liter x 0.9 = 28.16 A 10% blend of ethanol/gasoline would then have 30.24 MJ/L a drop of 3.3%. When cruising at a constant speed, the engine has to deliver "X" units of power. In the simplest case with constant combustion efficiency using either 100% gasoline or 10% EtOH/90% gasoline, you should only need to deliver 3.3% more fuel to provide those same "X" units. Will the delivered A/F be different? If you could leave the throttle alone and just add 3.3% fuel you would wind up at an A/F of 14.1:1 This is leaner that the stoichiometric value for the blend (~13.7:1 for 10%EtOH). With modern feedback controls more fuel will be added to get to stoich. In practice you would then just back out of the throttle slightly and incur some additional throttling losses that might bump the loss to 5%. It will matter if the engine control cannot compensate by running richer? If at cruise conditions your engine uses a fixed fuel delivery system (like older carburetted engines) then you will get the blend enleanment effect that was part of the rational for 10%EtOH in the first place. This lean shift was intended to reduce CO and HC emissions in older vehicle. The downside of this is that if your engine was calibrated on the ragged edge of its lean limit, this enleanment effect might be enought to push it over the edge to the point of lousy combustion stability. > Since both ethanol and methanol have less energy per volume of fuel, one > just adds more fuel until all of the oxygen is consumed. <snip a bunch of inapplicable handwaving and ooh-ha-ha> ...and we still wind up with less work done by a given volume of fuel. Call it lower MPGs or lower power, whichever you like, it doesn't really matter. For any set of conditions, one gallon of gasoline does more work than one gallon of ethanol or methanol, straight or blended with gasoline, simply because the alcohols contain less energy. And that's just always the case. Ethanol and methanol both contain less energy than gasoline, per volume unit, period, no matter what magic modifications you do to an engine. To the degree the effective air-fuel ratio is leaned by the use of alcohol relative to gasoline, the mixture can be corrected by dumping in more fuel, but this doesn't mean you get the lost power back. Putting the effect into real-world terms, as long as you have travel left in the accelerator, you can simply push it down further with alcohol-blended fuel than with gasoline to compensate for the loss, though MPGs will continue to suffer. However, this is just *compensation*, not deletion of the loss. The extreme case illustrates this: In the extreme case (Underpowered, fully-loaded vehicle climbing a mountain highway, let's say) when the accelerator is already on the floorboard and you're climbing the hill at 35 mph in the right lane with your blinkers going -- running on gasoline -- changing to a lower-energy-content fuel means your foot will still be on the floor but you'll be doing, say, 25 or 30 mph instead of 35. (I didn't run the calculations to come up with an exact mph difference; the point is illustrative without it.) DS >>Since both ethanol and methanol have less energy per volume of fuel, one >>just adds more fuel until all of the oxygen is consumed. [quoted text clipped - 9 lines] > volume unit, period, no matter what magic modifications you do to an > engine. No argument here. > To the degree the effective air-fuel ratio is leaned by the use of alcohol > relative to gasoline, the mixture can be corrected by dumping in more > fuel, but this doesn't mean you get the lost power back. Putting the Oh really. Why not? If the fuel energy was put back in with more fuel, then where did that energy go? > effect into real-world terms, as long as you have travel left in the > accelerator, you can simply push it down further with alcohol-blended fuel > than with gasoline to compensate for the loss, though MPGs will continue > to suffer. However, this is just *compensation*, not deletion of the loss. What do you think compensation does? You aren't making any sense here. > The extreme case illustrates this: In the extreme case (Underpowered, > fully-loaded vehicle climbing a mountain highway, let's say) when the [quoted text clipped - 4 lines] > didn't run the calculations to come up with an exact mph difference; the > point is illustrative without it.) No it isn't. Run the numbers. I'm real curious how your version of thermodynamics works. The fact is (and what the numbers I posted showed) was that for the same amount of air, adding the same equivalence ratio of fuel will in fact provide more fuel energy in the cylinder. > DS Nobody ever claimed on a volumetric basis alcohols were equivalent to gasoline. You seem to confuse power with fuel economy. They are not equivalent. You adjust the mixture differently to get max power than to maximize fuel economy. For fuel economy one DOES care about volumtric flow. But, for max power one wants to fully utilize the air inducted. If that means way more fuel flow, so what? Apparently your disparaging comment (ooh-ha-ha) means anything technical is beyond your comprehension. The fact remains that even under WOT conditions you can easily get at least the same power output from pure alcohols, alcohols/gasoline blends as with pure gasoline. That is readily verifiable on any decent engine test. > > To the degree the effective air-fuel ratio is leaned by the use of alcohol > > relative to gasoline, the mixture can be corrected by dumping in more > > fuel, but this doesn't mean you get the lost power back. > Oh really. Why not? Because there's nothing you can do to change the fact that alcohol contains less energy than gasoline. You're simply going to burn more alcohol than gasoline to do a given amount of work. > > The extreme case illustrates this: In the extreme case (Underpowered, > > fully-loaded vehicle climbing a mountain highway, let's say) when the [quoted text clipped - 4 lines] > > instead of 35. (I didn't run the calculations to come up with an exact > > mph difference; the point is illustrative without it.) > No it isn't. Well, ol' bean, I'm afraid I'm disinclined to put together a PowerPoint presentation for you. Perhaps if you think about it a little harder you'll catch on. > You seem to confuse power with fuel economy. For all practical purposes in street-driven cars, they are merely two means of expressing the same thing: Work done per unit of fuel consumed. It's just that talking in terms of "power" puts the emphasis on work done, while talking in terms of "fuel economy" puts the emphasis on fuel consumed. Fulminating about race cars, dyno engines and suchlike is fun and nifty, but not particularly applicable to the hordes of Chevies and Toyotas on US roads today. > Because there's nothing you can do to change the fact that alcohol > contains less energy than gasoline. You're simply going to burn more > alcohol than gasoline to do a given amount of work. The exception would be if the octane rating of the low energy fuel were high enough to greatly increase the CR. However, I don't think the octane of ethanol (I believe it is about 125) is high enough to allow that increase in CR. Yeah, fuel economy is a strong function of CR, but you'd have to increase it a LOT to get a 50% increase in efficiency. I tend to agree with Daniel that alcohol will never deliver the mpg that gasoline does, though it can deliver the same HP/CI. >> > To the degree the effective air-fuel ratio is leaned by the use of >> > alcohol relative to gasoline, the mixture can be corrected by [quoted text clipped - 6 lines] > contains less energy than gasoline. You're simply going to burn more > alcohol than gasoline to do a given amount of work. your still not getting it!!! only less per "volume" add the proper volume of alcohol back (as in richer mix) you add the total power, btu, any measure you want to use, and your power is returned to the same level. the only thing changed is the vol efficiency of the fuel. >> > The extreme case illustrates this: In the extreme case >> > (Underpowered, fully-loaded vehicle climbing a mountain highway, [quoted text clipped - 5 lines] >> > didn't run the calculations to come up with an exact mph >> > difference; the point is illustrative without it.) this will not happen unless you do not have the correct a/f ratio. If the ratio is changed to accout for the alcohol the power at WOT will not change. no speed reduction, only lower MPG. KB >> No it isn't. > [quoted text clipped - 13 lines] > nifty, but not particularly applicable to the hordes of Chevies and > Toyotas on US roads today. SignatureThunderSnake #9 Warn once, shoot twice 460 in the pkup, 460 on the stand for another pkup and one in the shed for a fun project to yet be decided on > > there's nothing you can do to change the fact that alcohol > > contains less energy than gasoline. You're simply going to burn more > > alcohol than gasoline to do a given amount of work. > > your still not getting it!!! only less per "volume" Yes. Less work per volume unit of fuel burned. I'm not sure what you imagine I'm "not getting". >> > there's nothing you can do to change the fact that alcohol >> > contains less energy than gasoline. You're simply going to burn more [quoted text clipped - 4 lines] > Yes. Less work per volume unit of fuel burned. I'm not sure what you > imagine I'm "not getting". if you add back the proper amount of fuel then no power loss is realized, regardless of BTUs per volume. hence same power, lower milage. KB SignatureThunderSnake #9 Warn once, shoot twice 460 in the pkup, 460 on the stand for another pkup and one in the shed for a fun project to yet be decided on > if you add back the proper amount of fuel then no power loss is realized ...which, of course, explains why FFVs are so much doggier when driven on M85 than on gasoline. >> if you add back the proper amount of fuel then no power loss is realized > > ...which, of course, explains why FFVs are so much doggier when driven on > M85 than on gasoline. Flex fuel is a compromise, that's why. It's basically a change in fuel map and spark timing if that. The compression ratio isn't changed to take advantage of the E85 for instance. If an engine is set up for E85 as it's fuel, then it should have equal or better power than an otherwise equivilent engine set up for gasoline. Will the E85 engine consume a greater volume of fuel? Sure. Just like the engine designed for 92 octane gasoline will consume more than the one designed for 87 octane gasoline. But there is no reason the engine running on 92 octane can't produce equal or greater power because the fuel has less energy per unit volume. > In article <Pine.GSO.4.58.0505131608500.20052@alumni.engin.umich.edu>, Daniel J. Stern wrote: > >> if you add back the proper amount of fuel then no power loss is realized > > [quoted text clipped - 7 lines] > If an engine is set up for E85 as it's fuel, then it should have equal or > better power than an otherwise equivilent engine set up for gasoline. > Will the E85 engine consume a greater volume of fuel? Sure. Just like the > engine designed for 92 octane gasoline will consume more than the one > designed for 87 octane gasoline. But there is no reason the engine > running on 92 octane can't produce equal or greater power because the > fuel has less energy per unit volume. I agree with most of your points, but how do you figure that an engine optimized for 92 would consume more fuel than one designed to allow use of 87? AFAIK there's not a significant difference in the energy densities of gasolines with different octane ratings as there is between gasoline and E85. If anything, I would suspect that the engine optimized for 92 would get the *best* economy of the three, all other factors remaining equal, on a MPG basis. nate No, it does not work that way. Ask any physicist and he/she will tell you. > No, it does not work that way. Ask any physicist and he/she will tell > you. A little context would help, if you expect anyone to understand your post. However, since you're replying to my post, I'm just going to have to assume that you're disagreeing with something I said...? nate Signaturereplace "fly" with "com" to reply. http://home.comcast.net/~njnagel > I agree with most of your points, but how do you figure that an engine > optimized for 92 would consume more fuel than one designed to allow use > of 87? AFAIK there's not a significant difference in the energy > densities of gasolines with different octane ratings as there is > between gasoline and E85. There is a difference between them in terms of energy per unit volume. It may be less of a difference but a difference none the less. The extra output that a higher CR gives usually doesn't translate into MPG. Some big blocks of the 60s had very high compression ratios for instance... >The extra output that a higher CR gives usually doesn't translate into >MPG. Some big blocks of the 60s had very high compression ratios for >instance... Unless you eliminate all the other variables, such as displacement, cams, exhausts, gearing, etc. etc.you can't make any sort of meaningful comparison at all. How about comparing a low compression Chevy 396 against an SS 396 with 11:1 compression? Swap each engine into the same Chevelle and run some EPA mileage tests, then let us know how they compare. SignatureLife is short - drive fast! http://www.geocities.com/scottenaztlan/ >>The extra output that a higher CR gives usually doesn't translate into >>MPG. Some big blocks of the 60s had very high compression ratios for [quoted text clipped - 3 lines] > cams, exhausts, gearing, etc. etc.you can't make any sort of > meaningful comparison at all. Not was not trying to make a comparison. I was making the point that thermal efficency doesn't mean mpg. Energy in over energy out doesn't have to equal volume of fuel over distance traveled. How about a different example. SAE student competition supermilage vehicles. Very small engines, very little hp, generally run in on-coast-on-coast- mode. > How about comparing a low compression Chevy 396 against an SS 396 with > 11:1 compression? Swap each engine into the same Chevelle and run some > EPA mileage tests, then let us know how they compare. Go for it, but it wasn't what I was talking about. >>The extra output that a higher CR gives usually doesn't translate into >>MPG. Some big blocks of the 60s had very high compression ratios for [quoted text clipped - 7 lines] > 11:1 compression? Swap each engine into the same Chevelle and run some > EPA mileage tests, then let us know how they compare. No, how about you replace the little 11:1 compression engine in a Toyota Prius with one that has an 8:1 compression ratio. Toyota MUST have thought there was an efficiency benefit with going to that high compression, right? Of course the laws of Thermodynamics back them up even better than the mere reputation of Toyota... >>I agree with most of your points, but how do you figure that an engine >>optimized for 92 would consume more fuel than one designed to allow use [quoted text clipped - 8 lines] > MPG. Some big blocks of the 60s had very high compression ratios for > instance... That's a strawman argument The implicit comparison is between a high-compression engine and a low-compression engine OF THE SAME POWER OUTPUT, and not between a 375 horspower 1969 440 Magnum in a 4000 lb. Charger and a 75 horsepower 3-cylinder in an 1800lb. Geo Metro. Given a hypothetical pair of engines of identical power output, the higher compression engine will always be more fuel-efficient, and to a greater degree than the penalty you pay for a fuel with *slightly* lower energy density. But since the cost of the higher octane fuel also goes up, it isn't necessarily more economical. >>>I agree with most of your points, but how do you figure that an engine >>>optimized for 92 would consume more fuel than one designed to allow use >>>of 87? AFAIK there's not a significant difference in the energy >>>densities of gasolines with different octane ratings as there is >>>between gasoline and E85. >> There is a difference between them in terms of energy per unit volume. >> It may be less of a difference but a difference none the less. [quoted text clipped - 4 lines] > > That's a strawman argument Guess you don't know what a strawman is, because I am not making someone else's arguement into an easily knocked down extreme. > The implicit comparison is between a high-compression engine and a > low-compression engine OF THE SAME POWER OUTPUT, and not between a 375 > horspower 1969 440 Magnum in a 4000 lb. Charger and a 75 horsepower > 3-cylinder in an 1800lb. Geo Metro. No, that wasn't what I was doing. I explained it to scott too. The last sentance is an example of how extra power from a high CR doesn't translate into better MPG. A 14:1 CR 7liter V8 didn't get better fuel economy than the run of the mill lower compression 7 liter V8 of the time. I was not holding power output constant and that is very clear. The extra power that makes the engine more thermally effiecent doesn't mean higher MPG. They are two different things and MPG has considerably more factors in play than the energy input over energy output. > Given a hypothetical pair of engines of identical power output, the > higher compression engine will always be more fuel-efficient, and to a > greater degree than the penalty you pay for a fuel with *slightly* lower > energy density. But since the cost of the higher octane fuel also goes > up, it isn't necessarily more economical. Let's just vary what we are testing, CR. You have vary other things to hold power output constant. But regardless, in both cases it will always be more fuel efficient in terms of energy in over energy out. This may not be true in terms of MPG. The other alterations to the engine to hold power output the same or the extra power the higher CR engine produces may not result in greater MPG. There are too many other factors in MPG to say this. >>>>I agree with most of your points, but how do you figure that an engine >>>>optimized for 92 would consume more fuel than one designed to allow use [quoted text clipped - 15 lines] > Guess you don't know what a strawman is, because I am not making someone > else's arguement into an easily knocked down extreme. Maybe its not what you intended, but from my chair that's exactly what you did. I pointed out that high(er) compression combustion is a more thermally efficient process by a great enough degree to offset the difference in energy content in the fuel required. Then you brought up HiPo 60s v8s, which have nothing to do with the basic question. >>Given a hypothetical pair of engines of identical power output, the >>higher compression engine will always be more fuel-efficient, and to a [quoted text clipped - 4 lines] > Let's just vary what we are testing, CR. You have vary other things to > hold power output constant. Granted, but let's look at a pair of trivial solutions: either throttle the higher output engine, or lug it down to a lower RPM where it produces the same power as the lower CR engine does at a higher RPM. Leave the cam and fuel system alone, and just optimize the ignition timing in both cases. Which one will be more efficient? The higher CR engine, even though its throttled which costs you some potential efficiency. Better yet, build two engines and hold everything EXCEPT compression constant, and measure the BSFC of each. The higher CR engine will produce more total power, but its BSFC will also be lower. > But regardless, in both cases it will always be > more fuel efficient in terms of energy in over energy out. This may not > be true in terms of MPG. The other alterations to the engine to hold > power output the same or the extra power the higher CR engine produces > may not result in greater MPG. There are too many other factors in MPG to > say this. All true, but largely irrelevant since its plainly obvious that higher CR ALLOWS you to design a package that is more efficient overall, if that is your goal rather than higher specific power output. The counter-example of thundering 60's v8s (much as I love them- I was out driving mine yesterday!) is not really a counter-example at all because the design goal was absolutely NOT efficiency. > Maybe its not what you intended, but from my chair that's exactly what > you did. Other people got it just fine. > I pointed out that high(er) compression combustion is a more > thermally efficient process by a great enough degree to offset the > difference in energy content in the fuel required. Then you brought up > HiPo 60s v8s, which have nothing to do with the basic question. Look, I brought 87 vs 92 octane as an example of theme. If you want to play usenet hair splitting fine. go for it, I don't give a sh.t, I'm too old for it. >>I pointed out that high(er) compression combustion is a more >>thermally efficient process by a great enough degree to offset the >>difference in energy content in the fuel required. Then you brought up >>HiPo 60s v8s, which have nothing to do with the basic question. > > Look, I brought 87 vs 92 octane as an example of theme. A "theme?" What "theme?" Floral or earth-tones? If you want to > play usenet hair splitting fine. go for it, I don't give a sh.t, I'm too > old for it. So am I, and that's not what I'm doing. I was pointing out what I perceived as an utterly incorrect generalization, not bring up totally irrelevant pseudo-comparisons of engines separated by 40 years in time and 200 horsepower in output. I'll admit that its possible that I'm old and senile enough to have completely missed the point. But I don't think so.... > If an engine is set up for E85 as it's fuel, then it should have equal or > better power than an otherwise equivilent engine set up for gasoline. > Will the E85 engine consume a greater volume of fuel? Sure. Absolutely correct. > Just like the > engine designed for 92 octane gasoline will consume more than the one > designed for 87 octane gasoline. I disagree on that one. The difference in energy content between 87 and 92 octane fuel is VERY tiny, and you can get so much better thermodynamic efficiency if you raise the compression to take advantage of 92 octane that the engine will probably consume LESS fuel by volume. Of course nobody does that, because it would still be more expensive because 92 octane costs a lot more. > Brent P wrote: >> If an engine is set up for E85 as it's fuel, then it should have equal or [quoted text clipped - 12 lines] > nobody does that, because it would still be more expensive because 92 > octane costs a lot more. *NOT*. BMW, Mercedes, Toyota, etc., all have engines that require 91+ octane (although they'll run w/o damage but with lower tune due to knock sensors that cause spark retardation) to get best power and mileage. Floyd >>> If an engine is set up for E85 as it's fuel, then it should have >>> equal or better power than an otherwise equivilent engine set up for [quoted text clipped - 18 lines] > > Floyd In spite of the "NOT" comment, you just made my point. Higher compression is more efficient to a greater extent than the energy loss per unit volume of the higher octane fuel. > I disagree on that one. The difference in energy content between 87 and > 92 octane fuel is VERY tiny, and you can get so much better > thermodynamic efficiency if you raise the compression to take advantage > of 92 octane that the engine will probably consume LESS fuel by volume. > Of course nobody does that, because it would still be more expensive > because 92 octane costs a lot more. But the problem is that a higher CR raises the power output of the engine, ie the thermal efficiency. Input/output. However that may not translate into MPG. I realized this back when I took thermo and realized that 60s big blocks could have very high CRs, yet still get 8mpg. It's not that the CR didn't give them greater thermal efficiency, it just didn't make it into the measure of MPG. That all aside, I was just going for the theme, and yeah yeah... this is usenet ;) There is also one small problem with this - It takes another source of energy to make Alcohol that can be burned. You have to distill it first. To get a high enough proof of Alcohol, you are going to have to run at least a double distillation process, if not a triple distillation process. So you are going to have to have another source of energy to fire a still of some kind to produce the Alcohol to use as a motor fuel. Using energy to produce energy is not a smart way to work. I know the corn and grain farmers want people to think we can use Alcohol as a fuel, but to do that we have to use another fuel first. Small problem here. roland > There is also one small problem with this - > [quoted text clipped - 13 lines] > > roland No, not a problem at all. Utilize the resource that you have in excess instead of converting your resources to buy from your enemies what you don't have...or are too lazy to develop. Thats where the loss is. Paying Arab chieftains for fuel convenience is like paying Mayan SunGod Chieftans in Mexico for sunlight. Anyway, last I heard, those Arabs couldn't eat their oil for substinence. -Bill >There is also one small problem with this - > [quoted text clipped - 7 lines] > >Using energy to produce energy is not a smart way to work. We use energy to produce energy all the time. Oil needs pumps, refineries, ships, trucks, etc. etc. etc. to be converted into gasoline and made available for consumers to purchase. If natural gas isn't coming out of a particular well with enough pressure to be sent down the pipeline, they run it through a compressor. And so on. Why is this OK for petroleum fuels but not for alcohol fuels? SignatureLife is short - drive fast! http://www.geocities.com/scottenaztlan/ >>There is also one small problem with this - >> [quoted text clipped - 7 lines] >> >>Using energy to produce energy is not a smart way to work. >We use energy to produce energy all the time. Oil needs pumps, >refineries, ships, trucks, etc. etc. etc. to be converted into >gasoline and made available for consumers to purchase. If natural gas >isn't coming out of a particular well with enough pressure to be sent >down the pipeline, they run it through a compressor. And so on. >Why is this OK for petroleum fuels but not for alcohol fuels? Probably because with alcohol, you end up with less than you started with. >>>Using energy to produce energy is not a smart way to work. > [quoted text clipped - 7 lines] > >Probably because with alcohol, you end up with less than you started with. Ah, so the NET energy is really what's important. If you burn the equivalent of 10 gallons of gasoline in order to refine 100 new gallons, your net gain is 90 gallons. OTOH, if you burn 10 gallon-equivalents of alcohol fuel in order to produce 5 gallons, then this is a net loss and is clearly stupid. So the question is, what is the energy cost to produce one gallon of, say, E85? SignatureLife is short - drive fast! http://www.geocities.com/scottenaztlan/ > gallons, your net gain is 90 gallons. OTOH, if you burn 10 > gallon-equivalents of alcohol fuel in order to produce 5 gallons, then > this is a net loss and is clearly stupid. In another thread it was reported that the process to produce ethanol is now better than break even. Even with a loss, ethanol can be valuable because it's a liquid fuel. For instance, the energy to create it can come from wind or nuclear power. Then ethanol can be put in the tank of a car and offer better performance than battery powered vehicles. > We use energy to produce energy all the time. Oil needs pumps, > refineries, ships, trucks, etc. etc. etc. to be converted into [quoted text clipped - 3 lines] > > Why is this OK for petroleum fuels but not for alcohol fuels? Because Alcohol fuels require nearly as much energy for production as they release when you use them. Petroleum doesn't. >>I disagree on that one. The difference in energy content between 87 and >>92 octane fuel is VERY tiny, and you can get so much better [quoted text clipped - 12 lines] > That all aside, I was just going for the theme, and yeah yeah... this is > usenet ;) I would suggest that the poor fuel economy might have been caused by a) cam timing that makes the idle sound like the drum intro of "Hot For Teacher" b) running the engine waaaay outside the sweet spot on the BSFC curve (due to a) that's going to be at a fairly high RPM) Most "big blocks," at least the ones that required premium gas, were tuned for maximum power, not maximum efficiency - now today those things go hand in hand, but back in the day, before mfgrs. had to worry about emissions, there were a few power tricks that cost a little in efficiency but drivers were willing to accept that tradeoff... nate Signaturereplace "fly" with "com" to reply. http://home.comcast.net/~njnagel > I would suggest that the poor fuel economy might have been caused by a) > cam timing that makes the idle sound like the drum intro of "Hot For > Teacher" b) running the engine waaaay outside the sweet spot on the BSFC > curve (due to a) that's going to be at a fairly high RPM) No, they're not efficient, but DAMN they sure are a lot of fun!!! :D > > I would suggest that the poor fuel economy might have been caused by a) > > cam timing that makes the idle sound like the drum intro of "Hot For > > Teacher" b) running the engine waaaay outside the sweet spot on the BSFC > > curve (due to a) that's going to be at a fairly high RPM) > > No, they're not efficient, but DAMN they sure are a lot of fun!!! :D No argument there! Nothing says "fun" like sitting at a stoplight and watching your whole front end sheetmetal dance around :) (anticipation...) nate >>>I would suggest that the poor fuel economy might have been caused > [quoted text clipped - 14 lines] > No argument there! Nothing says "fun" like sitting at a stoplight and > watching your whole front end sheetmetal dance around :) Or driving through a parking garage setting off all the car alarms as you idle past by with the top down and the A/C blowing... :-) >>I disagree on that one. The difference in energy content between 87 and >>92 octane fuel is VERY tiny, and you can get so much better [quoted text clipped - 12 lines] > That all aside, I was just going for the theme, and yeah yeah... this is > usenet ;) Big thing here is that CR effect on efficiency is for FULL THROTTLE. The efficiency really depends on the ratios of actual pressures, not the geometric compression ratio. Large engines usually run at very restricted throttle for most of time. The result is inefficiency. Smaller engine runs larger throttle opening to deliver same horsepower, with increase in thermal efficiency. Of course, there are many other factors, but if everything else is the same, running at larger throttle opening results in lower specific fuel consumption. (disregard onset of power enrichening) So two engines putting out same power will give efficiency edge to smaller one with higher throttle opening. I believe this is the idea behind some of these fancy new variable cycle engines, as well as ones that cut out some cylinders depending on load and TP. "Don Stauffer" <stauffer@usfamily.net> wrote > Big thing here is that CR effect on efficiency is for FULL THROTTLE. > The efficiency really depends on the ratios of actual pressures, not the [quoted text clipped - 10 lines] > engines, as well as ones that cut out some cylinders depending on load > and TP. Your "explanation" is not very right, either because you can't write clearly or because you are unclear on the concepts and science/engineering. I'm not going to attempt to re-cast your explanation, as it would take too much time, and all that stuff is readily available on the www. BMW's Valvetronic engines are un-throttled (variable lift valves) and appear to be about10% more efficient and 20% more powerful than the ones they replaced. Floyd |
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