The story that water can flow "too fast" through the radiator never made sense
to me. I suspect that the story refers to changes in the flow
characteristics, not specifically to the rate. It may be that at a certain
point flow becomes turbulent instead of laminar, and maybe that is a problem
either in the engine or the radiator.
But all else being equal, you get more flow of heat energy with a bigger
temperature difference between the hot and cold sides. So in general, higher
flow rates will result in higher heat transfer to the air.
The heat transferred per liter of pumped fluid is less at higher flow because
the exiting fluid is warmer than the low flow situation. But you have more
liters per minute, so you transfer more heat per minute.
In most situations, the actual flow through the radiator will be identical for
both a standard and high flow thermostat. It is able to regulate the engine
temperature just fine. But if the stock thermostat is wide open because
engine temperature is above the regulated temperature, then the high flow
thermostat will allow a bit better flow and maybe better cooling.
However, as has been said, originally the cooling system was good enough to
keep the engine cool in all situations. (Possibly not completely true!!).
So, if the cooling ability is no longer good enough, then the problem is not
the properly functioning standard thermostat. It is that the block can't heat
the coolant properly, or that the radiator can't cool the fluid properly.
-Tony
Sent from my IMSAI 8080
> On Apr 10, 2016, at 2:00 PM, triumphs-request@autox.team.net wrote:
>
> Date: Sat, 9 Apr 2016 17:14:26 -0700
> From: Peter Arakelian <peterara@msn.com>
> To: "triumphs@autox.team.net" <triumphs@autox.team.net>
> Subject: [TR] High-flow thermostat
> Message-ID: <COL127-W5784DD7FF36A73AD97FF7C1930@phx.gbl>
> Content-Type: text/plain; charset="iso-8859-1"
>
> I have the opportunity to get a high flow thermostat for my TR6. I compared
> the diameter of the portion that actually opens to a standard thermostat, did
> some area calculations, and came up with approx. 10 square millimeters larger
> on the high flow.Question is will it do anything. Two schools of thought
> have come up. First, yes, it will allow a greater flow of hot coolant into
> the radiator, much like a high flow water pump would, therefore in hot
> weather, it will run cooler.Second, no, in fact it may cause overheating or
> less actual cooling, because the coolant will pass through the radiator too
> quickly, like having removed a thermostat, and thus not cool enough.Thoughts
> from the group?
>
> Peter Arakelian - '71 TR6, Daily Driver
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