Ed,
Until pumping losses begin heating the water, the faster
the water goes through a heat exchanger, the greater
the BTU transfer. The higher the difference in temperature
between the water and what is heating or cooling it, the greater
the BTU transfer for a fixed flow rate.
I agree completely about a street motor and a thermostats.
The statement:
"And the faster the coolant flow, the less chance of
> developing a "hot spot" because the coolant is
> cooler."
Is false. It can be true in a certain engine but not all. I think
he has got his information mixed up.
To get "faster" coolant flow you have to pump harder and that
will produce more pressure in the block which WILL reduce
hot spots. I wish someone would braze a fitting on a freeze
plug, send the pressure to their logger and then tell us what
they saw. (using a stock type pump, of course)
This idea:
BUT, that moving the coolant
> too fast to "exchange" the heat has always resulted in
> a hotter running engine.
Goes back to the flathead racing days at Ascot in LA.
You couldn't run a flathead without restricting the flow
from the heads with a pair of washers. If you didn't, it
would over heat and blow out all of the water because
it was going too fast to cool the motor.
It worked even though what was actually happening
was not what the conclusion above specifies.
The got it backwards, steam pockets by the exhaust ports
blew the warm water out.
With 3/4 inch holes, at 5,000 RPM the pressure in the
block was close to 30 psi. and the steam pockets could be
lived with .... as long as you had a cool down lap where
you could buzz around at 4,000 with low load and let
the exhaust ports cool. The last thing you wanted was
a red flag. Every flathead would roll quickly to a stop,
the drivers jump out and everyone would stay back while
every flathead on the track, except the one that was
upside down would blow out the water.
Enough old history,
Bryan
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