[TR] Triumphs Digest, Vol 9, Issue 87

[Anthony Rhodes]

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 at autox.team.net wrote:
> 
> Date: Sat, 9 Apr 2016 17:14:26 -0700
> From: Peter Arakelian <peterara at msn.com>
> To: "triumphs at autox.team.net" <triumphs at autox.team.net>
> Subject: [TR] High-flow thermostat
> Message-ID: <COL127-W5784DD7FF36A73AD97FF7C1930 at 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