Steve Dorr discovered and uploaded this web site.

http://tinyurl.com/3uc3ed3

Produced by the National Automotive Radiator Association (NARSA) and by Richard F. Crook, Transpro, Inc.

The author maintains that all rads, no matter how good or
bad, always only drop the temperature 10 degrees F.

I was skeptical at first and then it dawned on me why.
The water coming out of the rad always goes back into the block
and then back into the rad 10 degrees hotter.

"That is, for a given [HEAT LOAD] and coolant [FLOW RATE], the coolant temperature drop through the radiator will be constant, and nothing anyone can do to the design of the radiator can change that. Adding rows or fins or face area or whatever will not change the temperature drop through the radiator."

Here is where the problem arises. If you add rows of tubes that will lower the resistance of the rad. Since the amount of water a centrifugal pump can pump depends on the total resistance in the cooling system the total water flow rate will increase. So the above sentence is not strictly true.

This is so typical of any cooling system. A change in one factor will
create a change in one or more other factors. This is what makes cooling
systems so hard to optimize.

I can highly recommend this $100 book.
"Compact Heat Exchangers by Kays and London."

It is the bible of cooling system design.

I cover some of the main points in my book "How to Cool Your Wankel"
available direct from me for $30 cash only. Contact me for a copy.

Paul Lamar