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Originally Posted by Rick & Connie
...So there are multiple factors involved in figuring the overall efficiency of an engine...
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The simple definition is the ratio of useful ENERGY output to total ENERGY input.
Since the input energy is heat content (BTUs) in the fuel, and the output is mechanical work (mechanical horsepower) some conversion is needed, but the efficiency can be calculated.
Rough numbers are 33% of the heat energy in the fuel is converted to rotational energy, 33% is output to the coolant and 34% is output in the exhaust. The proportions will vary but total must equal the 100% input.
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Originally Posted by Rick & Connie
...But what most people seem to overlook is the efficiency of the combustion itself. If I remember correctly, around 45% of the exhaust emissions on average are unburned hydrocarbons....
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Actually, most of the engine's exhaust is hot air!
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Originally Posted by Rick & Connie
...The factor most ignored though is the unburned fuel these engines waste. By creating a better vaporization and burn pattern in the combustion within the cylinder Smokey acheived somewhere near 70% complete combustion of the fuel. That doesn't in any way contradict the laws of physics now does it? Not when they can get more then 85% + combustion efficiency with modern furnaces...
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Well, now, the furnace has an unfair advantage here, since the desired output furnace
is heat, while the poor engine has to translate this heat into mechanical rotational energy! Remember it is not unburned fuel, it is wasted heat energy that lowers efficiency, and any engine will waste heat. More combustion energy goes out into the cooling system and out the exhaust pipe than is converted into mechanical energy.
Heat is not difficult to extract from combustion. High efficiency (90%+) furnaces have a second 'condensing' heat exchanger to recover more heat from the exhaust gases, resulting in even lower exhaust temperatures.
The combustion process of a modern gasoline engine is actually quite efficient. Assume the engine produces 1 gram of unburned hydrocarbons per mile. 30 grams (1.2 ounces) in 30 miles is not much fuel. An engine at 30mpg uses 99.2 ounces (6.25 pounds/gallon) of gasoline in 30 miles, while exhausting only 1.2 ounces of unburned hydrocarbons. This calculates to about 98.8% combustion efficiency, if I did the math right.
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Originally Posted by Rick & Connie
...I don't believe there is any practical way to achieve the high efficiency seen if furnaces burning fuel that is more in its pure state but why do people find it so hard to believe in 70% combustion efficiency...
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As I showed above, a modern gasoline engine achieves extremely high combustion efficiency. The issue is not combustion efficiecy, but energy conversion efficiency, or how much of this heat can be converted into mechanical work.
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Originally Posted by Rick & Connie
...I'm sorry if I offended anyone earlier. But I got quite frustrated by being ridiculed like some kind of gullible sucker who falls for the most likely impossible pipe dreams being sold to the unwary public...
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I am not offended, and I am not trying to ridicule.
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Originally Posted by Rick & Connie
...It's just that I know first hand on the one fuel system that does work... He drove the old truck for many thousands of miles with only two changes made. The rear end gearing. And the carburator he designed. And averaged slightly better then 100mpg. He the took the engine apart to inspect for damage because of his extreemly lean fuel mixture. No where near the commonly accepted absolute of 13.5:1 -14.5:1 and when he knew it would work he applied for a patent.
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Surely you didn't ride along with him to record how many miles he drove, how much gasoline he put in the tank. How did he then calculate 100 miles per gallon? You may believe this, but it cannot be accepted as proof.
When the air:fuel ratio is too 'lean' or too 'rich' the mixture cannot be ignited by a spark. You may be able to get the fuel to burn by applying some other ignition source, but not with a spark plug.
Adjusting the idle mixture screw on a carburetor results in the engine stalling if too lean or too rich. Been there, done that.
I remain unconvinced that any device, carburetor, fuel injector, or whatever, could provide a dramatically 'leaner' fuel:air mixture to an engine and allow it to continue to run.
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Originally Posted by Rick & Connie
...I hope with the way I explained the seperate aspects to be considered that are involved in the seperate factors of efficiency have shown you the practical,and very possible gains that can be made to modern engines without extreme re-engineering needed. It's entirely possible to greatly increase combustion efficiency, without much altering to thermal efficiency in any way...
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I hope I have explained why I can't believe that this is possible.
Best Regards,
Jim