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Re: Thermostat/Oil Cooler (long... but maybe useful...)

On 14 Aug 2001, at 13:19, Shad Laws wrote:

> Knowing the type of "testing" Gene Berg typically used, I can just about
> guarantee that those numbers hold no significance.  They were probably just
> pulled out of someone's..........

At least Gene wrote up his testing (in his own, very unique, style.) 
You've offered us a lot of rather unique thinking of your own, but 
backed it up with very little. Can you offer anything that can back 
up some of your claims? While I can't compete with you on your 
apparent knowledge of the various VW and Porsche cooling 
systems, I'm skeptical about SOME of your claims, particularly 
that the air flow to the type 4 oil cooler is shut off as the engine 
warms up. I'll have to look thru my manuals to see if I can find any 
evidence of that.

> And, this makes sense - the clearance between the pistons and cylinders is
> larger when cold than hot.  [BTW, this is one downfall of forged (Aluminum
> 2618... or is it 2816?  I don't remember...) pistons as opposed to the new,
> cast hypereutectic (Aluminum 390) pistons - the new ones run with a
> considerably smaller clearance due to lower thermal expansion.] 

If you actually check your numbers I think you'll find that the actual 
coefficients of expansion of different alum alloys don't differ by any 
significant amount. Of course we can debate what constitutes a 
"significant" difference, but we have to agree that the difference 
between iron alloys and alum alloys is something like a factor of 3. 
So I'm gonna claim tha a 10% difference in alum alloys is 
insignificant; calculate what difference this will make in cylinder 
wall clearance and we'll see that we can't even measure it. 

> And, the additional function of the T4 makes sense - if the heads get too
> hot, the heads will crack!  This is contrary to what you said that Berg
> preached - heats crack when they are too HOT, NOT when too COLD!

Here I'm confused. I thought there was agreement among all of us, 
Berg included, that too hot was bad.

> I mean, c'mon, why did they continue to use the magnesium-alloy
> case even when they knew that they didn't last?  Sim ple - getting
> magnesium from sea water was dirt cheap! 

This surprised me, but I have verified that this is basically the way 
that magnesium is produced in the US. We should not confuse this 
to mean that it is cheap. It's an electrolytic process, much like the 
production of aluminum and uses huge amounts of electricity. I 
think you will find that magnesium is more expensive than 
aluminum and that aluminum is more expensive than iron or steel.

So perhaps we should ask ourselves why they choose such an 
expensive material.

Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA

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