Efficiency of the standard ICE

In a modern engine with an O2 sensor, about 96% or more of the fuel is burned in the engine. The remaining 4% (or less) is burned in the exhaust system and catalytic converter. The energy losses are heat (to the cooling system, directly to the air, etc) pumping losses (energy required to move air through the engine) and mechanical losses (friction, making noise, etc).

Seems I did not do enough research! thanks for the reply ken. I found this http://www.greencarcongress.com/2005/02/doe_cofunds_12_.html

Though I still think there must be some lose due to fuel not being completly burned. The facts are there's too many mixed statisic's, that means there's not much heavy research in this area. Is just measuring the exhaust with an O2 sensor enough? As the combustable gases are H, O, and CO? H2+0=water and CO+O=CO2 ? So the gase that exit the exhaust must measure H, O, and CO to find how much was burned. The logic that I'm getting at is that if H and O is too diluted in other gases it will not combust, same with CO and O.

There's also the fact that if there is more "extra" gases inbetween these, there will be more heat produced in the combustion, and/or slower combustion.

What "heavy research" is meant? There are thousands or at least hundreds of papers reporting detailed contents of exhaust gas in all sorts of circumstances, and in a typical engine there isn't more that 1% (normally much less) of combustibles (including CO and H2) in the exhaust. As for acoustic losses, I don't think these are more than 1%.

This is a waste of cyberspace.

I suggest a bit of reading of standard thermodynamics (Carnot cycle, Otto and Diesel cycles etc., all of this at least 100 years old). Also - a few introductory texts on ICE engines, suh as Stone or Heywood will enlighten the "perpetual motion machine" fan. After all, an ICE is a heat engine and as such it cannot beat the good old Sadi Carnot cycle (about 1827?) which says that maximum theoretical efficiency is 1 - (Tl/Th). Thus if Th is about 2300 Kelvin for heat supply from typical SI engine combustion and Tl is 300 Kelvin for atmospheric heat dump, maximum theoretical efficiency (before friction losses, pumping losses, heat losses etc) would be 1- 300/2300 = 1 - 0.13 = 0.87.

The best Diesel engine I have come across (a huge ship's engine) actually delivers about 58% total efficiency - fuel to shaft.

Oh yes-very good- however the mpg of modern vehicles is only slightly better than early vehicles- & then only in a highway drive mode- not even considering the lower quality of fuel now- so, obviously, the efficiency you quote can be interpreted according to the answer expected!.

Oh yes-very good- however the mpg of modern vehicles is only slightly better than early vehicles-

Yes. And in the US, the overall MPG of the fleet as a whole, has actually gone down in the last 20 years, mainly because we drive bigger and bigger vehicles. The MPG standards being proposed (and which have the auto manufacturers in a fit) for 2020 can be met by a 1953 MGTD!

I am lucky to be a ICE consultant, and play around with these great machines some 10-50 MW in size, or much larger.

A VERY basic rule of thumb to use for concepts of how to use the heat is as follows:

30% work, 30% exhaust, 30% cooling, 10% radiation. As others have pointed out, most all fuel is burned, and we are left with waste heat in 3 areas not related to work.

Now, there are engines with 'work' efficiency routinely in 45% area and some, as pointed out, in the 50% area. To put this in perspective with real numbers you know, the fuel consumption on large units can be 20 - 200 liters per minute (5-55 US gallons per minute). PER MINUTE !

Have a look at what one of my clients is doing to recover heat:

http://www.wartsila-nsd.com/Wartsila/global/docs/en/power/media_publications/brochures/wartsila_trigeneration.pdf

http://www.wartsila-nsd.com/Wartsila/global//docs/en/power/media_publications/brochures/New_CHP_poster.pdf

And some fun brochures:

http://www.wartsila-nsd.com/Wartsila/global/docs/en/ship_power/media_publications/brochures/product/engines/rtflex96c_tr.pdf

Page 11 below is my favorite picture. I stepped down inside this engine on the laboratory test bed during development. Push rods were as big around as my leg.

http://www.wartsila-nsd.com/Wartsila/global/docs/en/ship_power/media_publications/brochures/product/engines/medium_speed/w64_tr.pdf

Have fun!

Years back, I developed training materials for airline pilots, and was thinking about fuel flow (from the perspective of someone who'd done a lot of work with cars and motorcycles, where is takes a LOT of cycles of an injector to fill a tiny test tube). If you threw buckets of fuel at the engines of a 747, I don't know if you could keep up with consumption.

Then there's the stuff you've worked with! Photos of such things are entertaining, because they can look just the the insides of a small engine. And then you see that spec in the photo that looks like a fruit fly... and it turns out to be a human.

since there's lot's of experts here, I'll ask this. What do you think of the RadMax by Regtech?

http://www.regtech.com/radmaxbrochure_trifold.pdf

www.regtech.com

here it says 1.5hp per cubic inch, displacement. That means a cubic foot of this, plus a flywheel, would give 2592hp!

This seems to be one of a bunch rotary engines with vanes that have received some press lately. They claim brake specific fuel consumption of about 25% less (better) than an efficient diesel, and far lower weight and size. Many of the things they say about the engine, such as smoothness and quietness would be true, if they can get it to work. Dealing with the friction of the vanes sliding under load would seem very difficult. If they end up coming even remotely close to their claims, then the market would be unlimited: if you were to multiply "goodness" factors for its extraordinarily low weight, small size, and high fuel efficiency, then this engine is 10 times better that a good diesel.

On the other hand, there is so much about the site and promo materials that is pretty sketchy and misleading. They suggest its use in any thing from weed trimmers to jet engines (as if it could function as a jet engine -- which it can not). The CEO in a promo video says "With proper sealing, you eliminate a lot of hydrocarbons going into the combustion chamber, which eliminates pollution, which is really important nowadays." This is utter nonsense, and given that this is a video produced by the company, they've had every opportunity to edit it to something that makes sense. Obviously, in the combustion chamber is exactly where you want hydrocarbons -- otherwise the engine would not run.

So... if it's the real deal, this is an outstanding engine (although I can't see how it can possibly get enough air through it to produce the claimed power -- the port timings seem far to short). However, the whole promo end of it seems fishy, as does the fact that they don't have a running engine to show after all these years.

So, who knows?

Well I believe there's coating for engines that bind to the metal and protect against corrosion, used for ethanol. There is most likely an oil that can do this. A coating that's slippery like ice, and spongy like rubber is all they need.

I've heard from someone first hand that they're building army vechicles with "a new kind of engine" in a factory where this person works. He/she wasn't suspose to talk about it. I think it's most likely this one because I remember reading news releases about how the military was very into this. I know there's many other kinds of "new engines" it could be one of those aswell.

how much can an engines efficiency be increased by gearing it differently, or anyother modifications that don't take major machining?

Engines do have efficiency curves but it would be hard to obtain a eff curve for a normal auto engine. For trucks (lorrys) there will be a curve for the driver to use to tell him when to shift, normally short shifting to 'lug' the engine is more efficient than running it out in speed before shifting. If you can get an efficiency curve then it is simple math to match the gear ratio in your differential and transmission gears to keep the car in the sweet part for your driving style. You need to do a 'pay out' study to see how many years it will take to recover the costs of modifications.

In spark ignition engines, the best efficiency (in terms of pounds of fuel burned per horsepower) is reached at the torque peak, and full throttle. When you close the throttle (for lower load) you increase pumping inefficiencies, and when you run at different RPM you fail to take advantage of the optimum flow rates (due partly to inertia effects) at the torque peak.

The problem is that you can't drive your car with your foot to the floor all the time (and in fact in most modern cars, you might not really "floor it" more than once a month, if you are a conservative driver.)

This problem is "solved" to a greater or lesser extent by hybrids (a very recent development, 1903 by Porsche) When the engine would otherwise be very lightly loaded (and therefore inefficient) you load it up by charging batteries, and try to turn of the engine altogether when when you can.

Less effective than a than the hybrid approach is to more heavily load the engine by using numerically lower gearing (tall rear end ratio, overdrive ratios, etc.). Of course then, you give up acceleration, so you need more speeds in your gearbox -- thus the current trend to 6 and 7 or even 8 speed automatics, 6 or seven speed manuals, etc.)

So yes, you could improve mileage by making the gearing taller, but probably the manufacturer picked a pretty reasonable set of ratios. (Where there is a good opportunity along these lines is in old muscle cars, pickup trucks, etc, in which rear end ratios are high for towing or acceleration [and where you can find different ratios in junk yards]. Then, a lower numerical rear end can make a noticeable difference in mileage -- but you give up towing ability or acceleration.) In most front wheel drive cars, changing gearing is not an option -- the pieces are not available.

Of course, there are many things you can do to improve mileage by changing driving techniques, and there are a gazillion websites on such stuff.

How about this, is the gas not completely burned? You said 1% is not used, but can the usless emission gases be alterd, by burning faster, or more completly?

I know that things that usualy don't burn can be burned in a plasma, and used for energy. (http://www.startech.net/)

This is what they claim happens

http://pesn.com/2005/11/25/9600207_Innovative_Hydrogen_Solutions_Inc/

http://en.wikipedia.org/wiki/Hydrogen_Fuel_Injection

either the energy is coming from the more complete burn of the gases, or it's coming from lessening the loses to heat.