First of all, my Tiger is mostly stock, and the gauge appears fairly
accurate. Original radiator, rodded out once or twice. My worst case
drive each year is coming home from British Car Day in Brookline. Mid
afternoon, sunny, hottest day of the week, if not the month. This year
was in the mid 90's. Less than a minute between stoplights for the
first
half hour, or so it seems. Anyway, the temp gauge gets up to the 230
area, but I don't blow any fluid. Once I get free of the stoplights, it
slowly comes back down to 215-220. I have a 170 thermostat, a 7 lb.
cap,
and keep the fluid below the "half full" level of the tank.
I will admit that I'm the wrong kind of engineer for this thermo stuff,
but here's some things to think about.
If you have "slow flow", the coolant comes out of the radiator much
cooler than it went in. Fine, but remember that back in the engine the
coolant is also flowing slow, so the temperature is rising....
Heat rejection is proportional to temperature difference. If the whole
radiator is at 100 C, as it would be with a really fast flow, it is
rejecting more heat than the same radiator with slow flow, and the
coolant coming in at 100 C and leaving at 50 C. Remember we are talking
about heat, not just temperature.
Analogy: Your the hot water baseboard heat in your house. If the
furnace
is running and the circulator pump is running real slow, the first room
gets a little warm, but the rest of the house doesn't. And the furnace
runs only part time, since the pump is running so slow that the water in
the furnace can get up to the shutoff temperature. Ask me about Feb.,
two years back. With the pump running at full speed, all the rooms get
warm, though in the last room the baseboards are a bit cooler, and the
furnace can run full time.
I know there are folks who can site successes on both the slow and fast
flow sides of the argument, but I just have a little more faith in the
fast flow side.
Stu
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