I need the engine efficiency rating when ethanol is used as a fuel when compared to gasoline. I can find which one is more efficient, but I need an exact percent
I believe a gasoline engine is about 14% efficient. An engine designed to run on gasoline running on ethanol is less efficient – ethanol contains fewer BTU. ethanol could be more efficient if it were used in an engine designed to run on ethanol.
Gas cars are about 25% efficient, and some race engines are up to 36% but wouldn’t be well behaved on normal streets.
Ethanol only contains 2/3 the energy per unit as gasoline. Diesel has about 115% of gas. Diesels operate in the 40 to 60% range, so are much better in a few ways.
Ethanol has less energy, but I believe it burns about as efficiently as gas. So you should be safe with the 25-36% range. Much of the efficiency is due to the compression ratio, and that is why diesels are much higher than gas. Ethanol and gas are run in the same engines with the same compression ratio.
The efficiency really doesn’t change. Ethanol contains approx. 34% less energy so you would burn about 34% more “fuel” but that’s only because the fuel has less energy in it, not because the engine has suddenly become less effecient.
Depending on a lot of factors a gasoline engine but an gasoline engine is between 25 to 30% efficent.
Well, it’s difficult to comment about a general four stroke engine as that is a little too vague.
Ethanol has approximately 2/3 the energy of gasoline (33% less energy) hence you need to use 3/2 as much fuel for the same amount of energy (50% more fuel) however technically that doesn’t change the efficiency as people have pointed out.
Ethanol does have a higher octane rating which means it’s less likely to ignite from compression alone and is a little slower to ignite hence the timing can be advanced such that the amount of time the gases are expanding during the power cycle is greater, this would increase efficiency but only if the engine was able to dynamically advance it’s timing to take advantage of the situation. If the engine could increase the compression ratio, as would be allowed by the higher octane rating, then there would be a more significant increase in efficiency but compression ratios are defined by the geometry of the cylinders, piston and axle and hence it’s very difficult to design a variable compression engine except as a laboratory testbed as is the case of the reference engine used to measure octane ratings.
Hence some four stroke engines may have a marginal increase in efficiency from the advancement of timing but generally there is no inherent efficiency benefit.
“In Brazil, the transition to the new fleet has changed the habits of many drivers and, in many cases, sharpened their math skills. Many drivers are keenly aware that ethanol has about 70 percent of the fuel efficiency of gasoline, which means they perform quick, pump-side calculations to determine whether the price of ethanol is at least 30 percent less than the price of gas. Some plot the distance of their trips and choose gasoline if it means the difference between filling up once or twice.”
I own a flex fuel car (2006 mercury grand marquis). And I have used both E85 and gasoline in it and calculated %’s for fuel economy for each fuel. I get 14.7% worse fuel economy using E85. However, here in PA gasoline is $2.55/gal and E85 is $1.79/gal. That means E85 is 30% cheaper here than gasoline. Which ultimately means I still save 15% on fuel by using it.
Gasoline engines are 35% eff, diesels are 37% and gas turbines are 30%. The best eff is a GE jenbacker natural gas engine at just over 41%. The peak efficiency for a ICE engine comes in at about a compression ratio of 14 to 1. 14 to 1 is to high for gasoline and to low for diesel. with proper turbo charging, the gasoline (spark ignition) can come closest as pointed out in the GE engine.
Now, when you include the start, stop, acceleration, air conditioning, electric windows, areodynamics, the effective efficencies are all over the place.
ethanol is just another fuel. If you were to design a pure ethanol engine, it would have a 12 to 1 compression ratio, below the optimum but it could be higher than a normal gasoline engine with a 10 to 1 ratio
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I believe a gasoline engine is about 14% efficient. An engine designed to run on gasoline running on ethanol is less efficient – ethanol contains fewer BTU. ethanol could be more efficient if it were used in an engine designed to run on ethanol.
Engine efficiency is same.
Now fuel mileage is different between E10 and E85 as alchohol has less energy per pound/ gallon than gasoline.
Gas cars are about 25% efficient, and some race engines are up to 36% but wouldn’t be well behaved on normal streets.
Ethanol only contains 2/3 the energy per unit as gasoline. Diesel has about 115% of gas. Diesels operate in the 40 to 60% range, so are much better in a few ways.
Ethanol has less energy, but I believe it burns about as efficiently as gas. So you should be safe with the 25-36% range. Much of the efficiency is due to the compression ratio, and that is why diesels are much higher than gas. Ethanol and gas are run in the same engines with the same compression ratio.
FYI – A turbine can get into the 60-70% range.
The efficiency really doesn’t change. Ethanol contains approx. 34% less energy so you would burn about 34% more “fuel” but that’s only because the fuel has less energy in it, not because the engine has suddenly become less effecient.
Depending on a lot of factors a gasoline engine but an gasoline engine is between 25 to 30% efficent.
Well, it’s difficult to comment about a general four stroke engine as that is a little too vague.
Ethanol has approximately 2/3 the energy of gasoline (33% less energy) hence you need to use 3/2 as much fuel for the same amount of energy (50% more fuel) however technically that doesn’t change the efficiency as people have pointed out.
Ethanol does have a higher octane rating which means it’s less likely to ignite from compression alone and is a little slower to ignite hence the timing can be advanced such that the amount of time the gases are expanding during the power cycle is greater, this would increase efficiency but only if the engine was able to dynamically advance it’s timing to take advantage of the situation. If the engine could increase the compression ratio, as would be allowed by the higher octane rating, then there would be a more significant increase in efficiency but compression ratios are defined by the geometry of the cylinders, piston and axle and hence it’s very difficult to design a variable compression engine except as a laboratory testbed as is the case of the reference engine used to measure octane ratings.
Hence some four stroke engines may have a marginal increase in efficiency from the advancement of timing but generally there is no inherent efficiency benefit.
“In Brazil, the transition to the new fleet has changed the habits of many drivers and, in many cases, sharpened their math skills. Many drivers are keenly aware that ethanol has about 70 percent of the fuel efficiency of gasoline, which means they perform quick, pump-side calculations to determine whether the price of ethanol is at least 30 percent less than the price of gas. Some plot the distance of their trips and choose gasoline if it means the difference between filling up once or twice.”
I own a flex fuel car (2006 mercury grand marquis). And I have used both E85 and gasoline in it and calculated %’s for fuel economy for each fuel. I get 14.7% worse fuel economy using E85. However, here in PA gasoline is $2.55/gal and E85 is $1.79/gal. That means E85 is 30% cheaper here than gasoline. Which ultimately means I still save 15% on fuel by using it.
Gasoline engines are 35% eff, diesels are 37% and gas turbines are 30%. The best eff is a GE jenbacker natural gas engine at just over 41%. The peak efficiency for a ICE engine comes in at about a compression ratio of 14 to 1. 14 to 1 is to high for gasoline and to low for diesel. with proper turbo charging, the gasoline (spark ignition) can come closest as pointed out in the GE engine.
Now, when you include the start, stop, acceleration, air conditioning, electric windows, areodynamics, the effective efficencies are all over the place.
ethanol is just another fuel. If you were to design a pure ethanol engine, it would have a 12 to 1 compression ratio, below the optimum but it could be higher than a normal gasoline engine with a 10 to 1 ratio