I have seen several conflicting documents on fluid speed vs. cooling
ability...one of those eternal debates I guess. Within the practical limits
of our pumps I am guessing faster flow has little effect, but the lack of
pressurization without a restriction does sound like more of a culprit.
I put an aluminum radiator from a 944 into my TR6 when I got tired of having
the stock one re-soldered. It is a little shorter and wider but overall
frontal area is comparable and it is lighter of course and cross-flow. It
came with the expansion tank (ugly) which allowed putting the cap on the
suction side. I blocked the bypass, fit a spiral impeller and closed up the
impeller to housing gap, reduced the impeller speed 10% and removed the stat
completely. So far it has worked well although I don't have a lot of
competition miles on it yet. It is fully shrouded and runs one electric fan.
I think I will try a restictor plate.
Mark Weathers
72 TR6
----- Original Message -----
From: "Bill Babcock" <BillB@bnj.com>
To: <WEmery7451@aol.com>; <fot@autox.team.net>
Sent: Monday, March 03, 2003 9:53 AM
Subject: RE: Head Cooling Problems
> I'll have to read the link. The thing engineers worry about (especially
> nuclear plant engineers at pressurized water reactor plants because their
> systems are designed to operate without boiling the coolant--same as a car
> only bigger) is actually "departure from nucleate boiling" which is the
> transition to bulk boiling. Bad for cars and nuke plants because the steam
> shrouds the heat transfer surface and dramatically reduces the heat
> exchange. Compared to flow considerations (which until I read the article
> I will still regard as small) lower static and dynamic pressure in the
> engine will have a huge effect. The seven pounds from the radiator cap
> gets added to five to 15 pounds from the water pump if it's exit from the
> block is reasonably restricted to keep the bubbles small.
>
> The easiest way to put the cap where you want it is to add an expansion
> tank, then you can keep the radiator and cooling system full. If you have
> a return line plumbed to the cooling system high point it will be
> self-venting. Peyote has a simple tank, made from a section of large
> diameter tubing. You can get a pretty aluminum one from Pegasus.
>
> -----Original Message-----
> From: WEmery7451@aol.com [mailto:WEmery7451@aol.com]
> Sent: Monday, March 03, 2003 7:16 AM
> To: Bill Babcock; fot@autox.team.net
> Subject: Re: Head Cooling Problems
>
>
> In a message dated 3/2/03 5:14:12 PM Pacific Standard Time, BillB@bnj.com
> writes:
>
> << It's probably more about the reduced pressure allowing bubbles to
> form--something engineers call nucleate boiling. I don't know about this
> "water moving too fast through the radiator" notion. Usually rapid flow is
> good for cooling because it keeps the boundary layer thin. >>
>
> I agree that probably ninety percent of the engine overheating problems
> result in the coolant flashing to vapor due to the loss of block pressure.
>
> We were doing some NRC smokescreen calculations directed at optimum flow
> rates in heat exchangers, trying to avert massive expenditures in plant
> modifications at the Happy Valley Nuclear Plants. We also had Kas slowing
>
> down coolant flow using larger pulleys.
>
> The talk of the times (60s), when many TR-3 drivers would show up at
> Nelson
> Ledges, would be optimum flow rate and restrictor washer size. I remember
>
> when ten to fifteen TR-3 would start a race, and we were all having
> similar
> problems. I seem to now be the last of them. This isn't to say that
> everyone couldn't have been wrong at that time. I am now taking Randall's
>
> "Stewart Components" seminar.
>
> Next questions for the cross flow radiator experts:
>
> 1) I assume that I could go to a radiator shop and have a cross flow core
> installed that will fit in the existing TR-3 radiator space.
>
> 2) How do you plumb the thing to put the radiator cap on the suction side
> of
> the system (from seminar)? This might not be possible with the tractor
> blocks.
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