[Navy Horn 16]

Originally Posted by Schurkey

True.


Clearly NOT. The water crossover is the last point before the thermostat, where the coolant LEAVES the engine for the radiator. The water INLET temperature would be measured at the lower radiator hose area in the water pump.



Folks over-cool the block trying to keep the intake manifold and cylinder head intake ports (and therefore the intake air/fuel stream) cool. As far as the intake air/fuel mix, cooler is better until you have fuel vaporization problems. It needs to be "just" warm enough to deliver a proper mix of fuel with the air to each cylinder; if it's too cold the fuel falls out of suspension in the air stream, doesn't vaporize very well, and too much goes out the exhaust unburned. Welcome to needing a choke and intake manifold heating methods in cold weather--you have to put so much fuel in the air because lots of it is not vaporized and is wasted. This is hardly a problem once the engine warms up.

You are correct, I had the flow backward in my head for some reason. Still, the temperature of the head and combustion chamber being cool is an important aspect that you are overlooking. It isn't just the temp of the air/fuel mix as it goes into the chamber..the temperature of the combustion chamber is important as well.

EngineMasters has done extensive testing on this, and they showed that the temperature of the fuel and air, and the temp of the head itself are what make the difference. The air/fuel mixture is going to fast between the carb and head to have significant heat transfer.

By having a cooler engine, you have cooler fuel, and avoid all the problems that you end up with by having an over-heated cylinder head. It's the whole reason aluminum heads exist (other than weight).