Swapping in a higher temp thermostat

[extragoode]

I read about a racecar inventer one time that created an engine that would produce 2-3 times the horsepower as his competors with the same displacement engine because it ran at 400-500 degrees F. Problem was it wouldn't reliably make it through a single race. I'll try to find that article, but it was several years ago that I read it.

The carnot cycle, like the stirling cycle, is more efficient when run a higher temperature and higher differential. In the stirling cycle I know it's because it provides greater expansion, but I'm not sure if it's the same in the carnot cycle.

Edit: It's crazy how hard it is to find an old article about a hot engine. I'm usually pretty good with google, but all I'm coming up with a bunch of people whining about their car overheating. Does anybody know what I'm talking about or remember any more?

[AndrewJ]

I'd treat a hotter thermostat as a slight, unquantifiable gain. The theory's all there, but it's just not something that I'd expect to actually be able to see in my gas logs.

Sure you may see a difference if you bump up the temps a few hundred degrees, but at only +10º you aren't likely to see much.

[Big Dave]

I put a 203 degree stat on my 7.3 and got a consistent 0.5 MPG increase. Not bad for such a cheap mod.

I also use Evans NPG coolant. This is a nonaqueous mixture of 10% ethylene glycol and 90% propylene glycol. It boils at a temperature over 400 degrees. I use it to defeat the cavitation problem common to 7.3s, but I have always wondered: "What if I could get a 300 degree stat?" One thing for sure: My heater would burn my fingers off. Even on the coldest days I have to temper the heater supply air.

[Duffman]

Originally Posted by Big Dave

"What if I could get a 300 degree stat?"

Bypass the rad and find out

[s2man]

That would be great. You've got the coolant problem covered. What about rubber seals at 300*F?

[Daox]

Originally Posted by AndrewJ

I'd treat a hotter thermostat as a slight, unquantifiable gain. The theory's all there, but it's just not something that I'd expect to actually be able to see in my gas logs.

Sure you may see a difference if you bump up the temps a few hundred degrees, but at only +10º you aren't likely to see much.

Thats pretty much what I was thinking.

[AndrewJ]

Originally Posted by Daox

Thats pretty much what I was thinking.

Still didn't stop me from putting in a 195º thermostat

Every little bit helps.

[LostCause]

If that is the case, have any of you considered ceramic coating the cylinder walls/pistons? I know ceramic engines have been developed by Nissan, Toyota, and Isuzu during the 80's that showed extreme efficiencies.

Ceramic Engine

http://www.youtube.com/watch?v=7Q0PcqqfA90

They never took off due to the brittle nature of ceramics and the fact it was like machining diamonds, but the concept is there. It seems the theory behind bumping up the thermostat is present, why not take it a step further...

- LostCause

[Daox]

Originally Posted by LostCause

It seems the theory behind bumping up the thermostat is present, why not take it a step further...

I'll answer that one. Money.

My thermostat needs to be replaced anyway, so I might as well use a more efficient one.

[dremd]

Going from 160 to the 190 (stock) was a big improvement in the tdi.

Ceramic coatings could improve efficiency . . .

Best credit I can give to ceramic coatings is

A friend of mine had Ceramic coated piston tops (7mgte heavily modded) he was running lean (before the days of cheap wideband o2's) and he melted his cylinder head. (yes that big beefy chunk of aluminum melted holes clean through) and the pistons live on in another motor. So yes, ceramic coatings can do amazing things, if I was to build a motor they would go on everything.