I knew that the internal combustion engine is very ineffecient, but I heard on the history channel that it only converts 30% of the energy in gasoline into mechanical energy ! That is terrible. Why is it so inefficient?
Engine Tech: How to improve efficiency?
- Thread starter sunil6784
- Start date
I_AM_CANADIAN
Member
Dean85GT
New Member
Heat.
In order to keep all of the parts of an engine in one piece and dimensionally stable, most of the heat produced by combustion must be washed away quickly by the coolant. It is possible that ceramic polymers can help improve the efficiency by allowing more heat to be retained in the cylinders, but at this time it is cost prohibitive, and the technology is still being fine tuned.
Also, there is a lot of energy lost to the exhaust system, which is why turbos are so great.
jason
In order to keep all of the parts of an engine in one piece and dimensionally stable, most of the heat produced by combustion must be washed away quickly by the coolant. It is possible that ceramic polymers can help improve the efficiency by allowing more heat to be retained in the cylinders, but at this time it is cost prohibitive, and the technology is still being fine tuned.
Also, there is a lot of energy lost to the exhaust system, which is why turbos are so great.
jason
50bomber
New Member
First and Second law of thermodynamics, no such thing as free lunch and that entropy is a ******.......no perpetuum mobile, grasshopper.......
88Stangboy
Banned
have a light weight rotating assembly, light weight valvetrain, have a great air-fuel ratio, a supurb ignition system with very powerfull spark, a turbo, canted valves, synthetic oil....basically lower the weight of everything, and try to loose as much friction as possible. The engine uses a certain percentage of its own power just to turn itself over, make it as light and friction free as possible and get it to burn as much of the air and fuel as possible on the compression stroke. Diesal engines are pretty efficient...
Diesel has several advantages that gasoline doesn't have.
There is no throttle body. Power is regulated with the fuel flow. On a gasoline engine the tb decreases the efficiency by restricting airflow.
Diesel has a higher heat density than gasoline.
Diesel fuel allows the use of higher compression ratios.
Thats all I can think of right now.
I don't remember any specific numbers but I want to say that Diesel engines still do not exceed 50% efficiency.
jason
There is no throttle body. Power is regulated with the fuel flow. On a gasoline engine the tb decreases the efficiency by restricting airflow.
Diesel has a higher heat density than gasoline.
Diesel fuel allows the use of higher compression ratios.
Thats all I can think of right now.
I don't remember any specific numbers but I want to say that Diesel engines still do not exceed 50% efficiency.
jason
50bomber
New Member
Yeah, but diesels run out of steam at like 1500 rpm, 
w/o turbos they are nothing..........How about direct gasoline injection, infinitely variable valve timing and intake manifold length a la BMW 7 series?
w/o turbos they are nothing..........How about direct gasoline injection, infinitely variable valve timing and intake manifold length a la BMW 7 series?
Diesel's do have TBs, or most of them do, don't they? Fuel/Air ratio is important on them as well. I don't see too many of them, so I can't be sure. next time a CTD, Powerstroke, or Duamax comes in I'll be sure too look. Diesels are great becasuse they use the heat of compression to fire, they use the fuel injectors to fire actually. It's called Direct Injection, something I don't understand why isn't done to a gas motor. Imagine, running 16:1 - 20:1 compression with a blower on pump gas.
There are engine's and motors, the difference is that while a motor just coverts energy, the engine actually has to make it. Our vehicles have engine's which have to convert a flamable liquid into rotational energy.
I agree with 88Stangboy. You need to minimize friction and try to get all the power to the wheels.
In a four-cycle motor, only one of those cycle's is creating power. After the combustion stoke, where the power is made, then the engine has to push the old gasses out, then pull the new gasses in, compress them for the next combusiton cycle. On top of this, you have to turn the weight of the rotation assembly, the camshaft, the oil pump, and other accesories that are running 100% of the time. A steam turbine is a very effeceint motor, that is what most powerplants such as nuclear and coal burning plants use. Of course they are in constant use, while in a car, with all the cold start ups and all, the efficency would be lost.
There are engine's and motors, the difference is that while a motor just coverts energy, the engine actually has to make it. Our vehicles have engine's which have to convert a flamable liquid into rotational energy.
I agree with 88Stangboy. You need to minimize friction and try to get all the power to the wheels.
In a four-cycle motor, only one of those cycle's is creating power. After the combustion stoke, where the power is made, then the engine has to push the old gasses out, then pull the new gasses in, compress them for the next combusiton cycle. On top of this, you have to turn the weight of the rotation assembly, the camshaft, the oil pump, and other accesories that are running 100% of the time. A steam turbine is a very effeceint motor, that is what most powerplants such as nuclear and coal burning plants use. Of course they are in constant use, while in a car, with all the cold start ups and all, the efficency would be lost.
50bomber
New Member
Hmmm how about a two stroke diesel with a roots blower for good scavenging and a turbocharger......it has been done.....whooo
. Won't earn any EPA awards....
. Won't earn any EPA awards....
onefstsnake
New Member
In physics I learned that all work causes some heat, and eventually everything will be converted to heat.
I dont know the exact scientific words...
Anyone see the thing about F1 cars going to a Hybrid system?
I dont know the exact scientific words...
Anyone see the thing about F1 cars going to a Hybrid system?
bgjohnson
Founding Member
Alot of it is friction and rotational Mass.
Also a Huge part is volumetric efficiency!
Think of how much power you would gain if you didn't now have valve springs,and oil pump, or water pump, along with taking a piston, stopping it then making it go in the reverse direction!
here would be an crazy efficient engine. A rotory engine with a turbo, solenoids for valve springs(BMW uses them on some motorcycles) and an electric water pump along with a dry sump system, now that would be sweet.
Also a Huge part is volumetric efficiency!
Think of how much power you would gain if you didn't now have valve springs,and oil pump, or water pump, along with taking a piston, stopping it then making it go in the reverse direction!
here would be an crazy efficient engine. A rotory engine with a turbo, solenoids for valve springs(BMW uses them on some motorcycles) and an electric water pump along with a dry sump system, now that would be sweet.
88Stangboy
Banned
Also a Huge part is volumetric efficiency!- bgjohnson
Agree'd
And rpm's have alot to do with it, as rpm's go up, combustion engines become less efficient. Thats why all your torque is down low, no up in the rpm' range.
RPM's go up----Engine efficiency go down.
Compression ratio, ignition timing, thermal coatings, plug location and chamber design also have a large part in it. Thats all Thermal efficientcy.
Agree'd
And rpm's have alot to do with it, as rpm's go up, combustion engines become less efficient. Thats why all your torque is down low, no up in the rpm' range.
RPM's go up----Engine efficiency go down.
Compression ratio, ignition timing, thermal coatings, plug location and chamber design also have a large part in it. Thats all Thermal efficientcy.
5.0 Nostalgia
10 Year Member
If you want to improve engine efficiency, retard your timing, shift at 2000RPMs, don't use your AC on the street, (but use it on the highway), drive slow, and keep your car as light as you can.
88Stangboy
Banned
I mean only 1/3 of the gasoline that you put into your engine is actually turned into rotating energy through the crank. After the gas actually explodes it all becomes mechanical efficientcy, that would factor into valve springs, crank, rods, etc all the items that cause friction or resistance such as a power steering pump or piston rings. Shifting at 2000 and not using you a/c is just using the energy produced more efficiently and getting better gas milieage, lol. Wouldn't it be nice if we only had to pay for the amount of gasoline that we actually converted into power? We'd only have to pay for 1/3 of what we actually bought, gas would only be about 78 cent around here. Oh well...i can dream....
Black1987Stang
Active Member
50bomber said:Yeah, but diesels run out of steam at like 1500 rpm,
A couple reps from BMW came to my college and brought a few of their new cars. It has no throttle body or camshafts....All controlled by varying how much the solenoids that control the valves move.....No mechanical water pump....Electric, doesnt turn on during warm-up session for quicker warm-ups and since the worst emissions are during warm up it doesnt put out as much emissions...They now even have infinity ratio steering so it can suit to ur need if ur parking or on the highway, I forget how it works though.
Theyre still experimenting with Direct Gasoline Injection (GDI) from what I know of anyway. It will allow for much leaner air/fuel mixtures. Since diesels have it i would think it would be the same principle for gas engines.But they will need to construct the fuel system better since it will need higher fuel pressure to overcome the compression pressure inside the cylinder and the ability for the injector to seal properly and handle the high heat...Increases volumetric efficiency since only air is moving through the intake manifold, Since the fuel will be delivered at such a high pressure it will be in more of a vapor form not a liquid form. Theres alot more advantages but thats some anyway
90mustanggt makes a good point since they only make power one out of strokes, the other 3 strokes it just uses energy and to get rid of the exhaust and make suction for the incoming air....Now only if they could design a enviromently friendly 2-stroke V8 engine
, might be slow at first but imagine the power band it would have 
1EVIL88VERT
New Member
How about turbine power! They are much more efficient than piston engines with less emmisions to boot. Just think of the power you could have from a new gen turbine that can fit under the hood of your car. Now what to do about that whole spool up time thing and melting the guys car behind you need to be addressed.
