Call this second try to get this thru.
Erich,
You have run afoul of a server rule that I can't override. You'll
need to break this email into two parts and resend if you want it to
go to the list.
Sorry,
Mark
I'm glad your car is behaving better.
Conduct this experiment on the stove at home.
Place a pot of cool water on the stove with thermostat suspended from a coat
hanger or welding wire. Stick a thermometer in there too.
Turn on the burner on low and let the temp rise SLOWLY.
What the behavior of T stat vs. water temp.
What you will obsere is this.
Below Thermostat temp rating : Tstat Closed
At rated temp: Tstat just cracks open.
15 degrees above rated temp: Tstat reaches full open.
In between the opening of the stat is determined by the temp.
In this range the Tstat is actively controlling the water flow rate to keep
the temp within that 15 degree window.
Outside that window the stat is closed or wide open and thus does not
"control" the temp.
On a 160 thermostat, if the car is running hotter than 175 it is because
your cooling system is not capable of making it run cooler.
All ways remember that the water side of the cooling system is a closed
loop. If you slow the flow down in the radiator so it has more time to get
rid of heat, it also is spending more time in the engine picking up heat.
This means the system will have larger temp swings as you look around the
system. The outlet of the radiator will be cooler and the outlet of the
engine will be hotter. It might even get so hot in the engine that the
water boils next to the cylinder head. This is a bad thing.
>From my heat transfer textbooks:
The amount of heat picked by a flowing liquid is
Qdot= mdot*Cp*(Thot-Tcold)
Qdot is the Heat transfer rate BTU's per Hr for us Anglophiles. KiloWatts
for the rest of the world.
Mdot is the mass flow rate. Pounds per hour or Kg/sec
Cp is the specific heat of the liquid. Units are BTUs/pound-Degree F.
Thot- Tcold is the change in temp of the fluid.
So if you want to keep the temp of the fluid down AND carry a lot of heat,
the equation tells you what to change.
1. Use a fluid with a high Cp. Turns out pure water has a pretty high Cp.
Ethylene glycol is much lower and a 50-50 mix is not much better. This is
why you see advice to run straight water and a coolant mix. They are
telling you to maximize Cp.
2. Increase mdot. This means flow more water. That means a higher flow
water pump.
The only downside to a high flow pump is it takes more hp to spin.
My personal Tiger cooling saga is long and convoluted, but I replaced/
upgraded every component in the sytem with stuff that other Tiger owners
said worked for them.
My car still ran hot at speed or climbing hills. If I drove fast enough it
would boil over.
I replaced the stock pump with one from Edelbrock. The change was immediate
and dramatic. Temps at 65 mph dropped from 220 to 190. At 80 mph the temps
stabilized at 210 instead of climbing above 230.
Erich
----- Original Message -----
From: "Richard" <rcsphx@qwest.net>
. I had always
> thought that the thermostat was used to bring the engine up the normal
> operating temperature as quickly as possible, and that once the opening
temp
> of the stat was reached that it remained in the full open position until
the
> engine cooled down. >
> Richard
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