> Dennis Wilson was staying with me a few weeks ago and
> he said his spitfire racing book recommends leaving the
> thermostat on but welding it open. The car is supposed to
> run cooler because it stays in the radiator longer.
> I am ever concerned about the TR7 running hot(although the seasons
> are changing it is still pretty hot here in Las Cruces). Do you
> all agree with this??
Not me. I think that unless you are running WOT most of the time,
you are better off (especially in New England...) with an operational
thermostat. The primary purpose of the thermostat is to allow the
engine to reach operating temperature in a reasonably expeditious
manner - by not allowing the coolant to circulate until operating
temperature is reached. It is bad for your engine to be operating
below the temperature at which the thermostat opens. Maybe not as
bad as operating significantly over that temperature, but it still
is bad. This is because bearing, ring, piston skirt, and other clearances
are calculated based on the level of thermal expansion encountered
at operating temperature. So if your engine is running cold, the
clearances are wrong. This is why it's better, once the oil film is
properly established, to go ahead and drive the car instead of sitting
there waiting for it to warm up - due to the extra waste heat of running
under load, it will warm up to operating temperature more quickly.
While running under load at less than operating temperature is slightly
worse (in the engine wear department) than running at idle, the amount
of time involved is so much less that you come out ahead.
To summarize, normal running should occur at rated operating temperature.
Screwing around with the thermostat will NOT improve your cooling. If you
overheat, get a better radiator.
--
---
John R. Lupien
lupienj@wal.hp.com
|