Smokey-Yunick engine
 

(nothing to do with ethanol)

People should read: http://en.wikipedia.org/wiki/Smokey_Yunick#Automobile_racing a few things about his cheats. ;)

That is plain BS and misinformation -- in a well adjusted engine, that should be well over 80%.

As for the S-Y engine, it looks good on paper and it's specs are not outright impossible like many other well known "inventions" such as the 200 mpg carburator; however, it still sounds a bit too good to be true.

If it were indeed as good as claimed, automakers would've licensed it a long time ago, unless he were asking some insane amount of money.

Again, completely wrong: http://www.csmonitor.com/2005/0505/p01s04-usfp.html
And I'll skip the rest of your 'facts'....

More like 99 percent of the fuel burns completely, with the cat taking care of the rest. Maybe he meant 25 percent thermal efficiency, which is close to being correct. The problem is that the theoretical maximum is only about 35 percent for an otto cycle internal combustion engine.

A five minute test at 80mpg proves nothing. I once got 100mpg (as shown on the trip computer) in a rented Cadillac, coasting downhill.

I may have been a bit conservative with "well over 80%", but also, I didn't include what is burned in the CAT because that normally goes to waste.

I know he may have meant thermal efficiency, but since he quoted 2 very different numbers in the same paragraph, one of them is gotta be very wrong.

However smart and resourceful he was, the laws of physics apply to everyone with no exception. And because of all the trickery he had done on NASCAR cars, I don't find it unbelievable that there were some cheats behind those mpg numbers. ;)

Based on a quick look, it appears he's trying to scavange some of the waste heat, and that's not what I think would be an adiabatic engine. Adiabatic engines are simply engines with little or no additional cooling, but because of the high temperatures, they present some serious engineering challenges. In addition, they're also very bad about NOx emission.

"If it were indeed as good as claimed, automakers would've licensed it a long time ago, unless he were asking some insane amount of money."

Anyone wishing to read about it, including patents, and copy it for personal use could do so to verify it works.

I don't doubt that it works. What I don't believe is the specs -- it's just to good to be true. Making an engine that gets over 1 HP/CID is not that difficult, same for a low emission. Making one that is significantly more efficient than what we have today, however, is much harder, but for the argument's sake, let assume it's possible. But making one that does all three? I can't say it's impossible, but it's definitely non-trivial. Given CAFE and the current fuel prices, it would make no sense to not use it, if it would work as well as claimed.