Automotive engines waste a lot of energy out the radiator because they have to run cool. What are the obstacles to building a reciprocating engine which will run at high temperatures and therefore be more efficient.
It seems to me that a combination of ceramics, high temperature alloys, and a synthetic lubricant which remained stable at high temperatures could do the trick.
Indeed you’re right.
Engines used to run 160-180 deg F, Now it is possible to run at an operating temp in excess of 200 degrees, using hi temp lube and high pressure cooling systems.
The last time I was at the local Harley dealership (where a friend of mine works), they had a 2002 Fat Boy on a dynamometer, and it’s operating temp was 286 deg, IIRC. It blew my mind, because I was always used to 160 - 220 degrees. Now that’s an air-cooled motor, so I don’t actually know if this is relevant to the thread. I do know that at some point, however, you’re gonna run into a detonation problem (fuel/air mix igniting before the plug sparks) if you run too hot, since the actual temperature of the compressed air-fuel mixture goes much beyond engine temp.
I remember reading a while back about Smokey Yunick, and he had modified an IC engine to heat the air fuel mixture to about 400 degrees, and the engine ran pretty hot. I’m trying to find the link to it. I think it was called the “hot vapor engine” and it made pretty decent power.
The last time I was at the local Harley dealership (where a friend of mine works), they had a 2002 Fat Boy on a dynamometer, and it’s operating temp was 286 deg, IIRC. It blew my mind, because I was always used to 160 - 220 degrees. Now that’s an air-cooled motor, so I don’t actually know if this is relevant to the thread. I do know that at some point, however, you’re gonna run into a detonation problem (fuel/air mix igniting before the plug sparks) if you run too hot, since the actual temperature of the compressed air-fuel mixture goes much beyond engine temp.
I remember reading a while back about Smokey Yunick, and he had modified an IC engine to heat the air fuel mixture to about 400 degrees, and the engine ran pretty hot. I’m trying to find the link to it. I think it was called the “hot vapor engine” and it made pretty decent power.
One of the problems is with increased combustion temp you have a increase in NOx (usually a decrease in CO and hc’s). The egr valve is designed to limit the NOx’s by recurculating exhaust gasses so the combustion won’t be as hot - and yes it cost mpg’s.