> > > This is what I would call an "invented rationalization".
> > > There is no way that more coolant flow will give less cooling.
> > > It is a thermodynamic impossibility. Much more likely is that
> > Isn't it possible that the coolant could leave the radiator before much
> > of the heat it contained was transfered to the air flowing through the
> > radiator?
Time isn't the only thing you've varied, Mike -- assuming that you
did shorten the time (which I doubt -- see below for the real answer),
you increased the quantity of coolant that passes through the radiator
in direct proportion, for a net change of zero.
Let's say that removing the thermostat doubles the flow. Since
pressure and internal radiator volume remains constant, this means
the coolant must spend half the time in the radiator, which is why
you figured it was cooling less. That's true -- but you've got
*twice as much* coolant in the radiator during the same time. So if
a liter of coolant loses heat at a rate equivalent to 10 degrees C
per second, doubling your flow rate cuts the temperature loss for that
liter of coolant to 5 degrees total -- but you had two liters of
coolant going through the radiator during that second because the
volume and the rate are proportional.
It's the old man-month analogy. If you pay a consultant $50 an
hour, you can get the same amount of work done in half the time if
you hire two consultants, but it costs you the same amount of money.
(Or you can do what my last contract employer is doing, which is
hire a bunch of people and take forever to pay! :-(
Anyway, the reason your car is probably overheating is that in some
cars, the thermostat also serves as a flow splitter to make sure that
coolant goes to the right passages in the head. If you remove the
thermostat in a B and (if memory serves) a TR4, they run hotter because
the sleeve around the thermostat body causes a fixed percentage of the
coolant to go into a side passage. If you yank the thermostat, the
coolant doesn't go into this side passage or the rate/volume gets
screwed up, and the car runs hot. Moral of the story: you can't fool
mother Nature. Put the thermostat back (or get a new one at the
right rating -- it's possible your thermostat was faulty).
--Scott "This is how we know the Earth to be banana-shaped" Fisher
|