>From a professional engineer who used to design car engines for Lotus (and
somewhat summarising the article Peter referred to) -
A slower flow rate will result in cooler coolant leaving the radiator. And
for just the same reason, a slower flow rate will result in hotter coolant
leaving the engine. Because it has more time to cool/heat up in each area.
What is much more important is how much heat is rejected from the radiator.
This is equal to the temperature drop x flow rate x specific heat capacity
of coolant. The greater the difference between the radiator temp and the
air temp, the greater the heat rejection - so (somewhat perversely), a
hotter radiator will reject more heat, and help your engine run cooler.
Therefore faster flow equals more heat rejection equals better engine
cooling.
However, there comes a point where increasing the flow even by a large
amount will only increase the heat rejection by a very small amount (this
will be when the radiator out temperature is only a little below the
radiator in temperature), so there's very little gain to be had by higher
flow rates. How close a standard MGB is to this point I have no idea (and
of course varies with engine speed, and thus pumping speed!).
This all ignores any secondary effects that may occur, such as cavitation in
the radiator at very high flow rates which would reduce the heat transfer
from water to air, I doubt our radiators are anywhere close to this
happening.
Any clearer, anyone?
Richard & Nancy (on the road any day soon, I hope!!!)
This email and any attached files are confidential and copyright protected. If
you are not the addressee, any dissemination of this communication is strictly
prohibited. Unless otherwise expressly agreed in writing, nothing stated in
this communication shall be legally binding.
|