Richard Lamb wrote in message ...
Dan,

Just a dumb question about marine installations...

For a water cooled engine, why _not_ keep the radiator?


Richard

Takes up a lot of room for the rad, fan, baffling and extra
pumps. Heat in the boat in the summer isn't welcome, either. Makes it
uncomfortable for the passengers and can lead to problems with more
fuel vapors as tanks get too warm. (Boats have to have exhaust fans
for enclosed engine compartments and fuel storage spaces, as fuel
vapors are heavier than air and will collect in the hull until some
spark ruins your whole day.) Further, the engine exhaust must be water
cooled, in most cases, since there is no airflow around the pipes and
they'll get hot enough to set fire to the boat. In straight inboards,
the water flow enters the bottom pickup, through the pump, goes to the
oil cooler, then to the exhaust manifold jackets, then into the
engine, out of the engine and into the exhaust pipes themselves where
it mixes with the hot exhaust gases and keeps them cool enough until
they're ejected. A radiator or heat exchanger can't do this, and the
entire length of exhaust pipe needs jacketing or you have to use
little short noisy stub pipes, off an open engine, that are insanely
loud and illegal almost everywhere.
Dropping an auto engine into a boat is nearly as much hassle as
putting it into an airplane. The same issues of weight, torsional
resonance (though not as severe), cooling and so on are all present.
My little 13' boat, with that supposedly 250 HP 283 from an early
Corvette only maxed at 42 mph, primarily due to the 800 lbs of engine
and marine transmission (another subject entirely) causing way too
much induced drag at planing speeds. One mile per gallon at full
throttle; the engine-driven fuel pump couldn't keep up with it. But
she sure popped skiers out of the water in a hurry...

Dan