>The root cause of problems in the activity is the activity itself. ..... If you can't put numbers on the design criteria then nothing can be produced to meet them, nor is there the possibility of >a test to determine if it meets the criteria.
Nicely said, Ernest. A useful discussion might concentrate on definition of the objectives.
Rather than be avoided, I'd suggest that "Marginal" is to be sought after  - the ideal. Everything is a compromise. Make the cooling adequate for full power low level and you give up advantages in other flight regimes. (speed).  I don't think I've ever used full power except occasionally on take-off. I fly on the temp gages and don't see anything wrong with this. To cool at full power under all circumstances I'd have to add scoops and drag that would probably reduce high altitude cruise speed by maybe 30 kts. This is not acceptable. A compromise is the best answer here.

Here's my definition for an adequate cooling system :
Pick your max operating ground level OAT - I used 96F.

Able to maintain oil & coolant temps at idle / minimal rpm on the ground at 220F or less indefinitely  (you could put a time limit on this one)
Able to take-off and climb to patten altitude at or below 220F, then do it again within 2 weeks (ideally twenty minutes)
Able to cool to below 220F when throttled back on downwind
Able to maintain oil and coolant at or below 220F while climbing to altitude at >= 1000 fpm
Able to cool at or below 220F during high speed high altitude cruise for the aircraft in question.
Able to cool at engine ideal (185F?) during standard cruise altitude and speed / for that pilot / aircraft / usual location.

This definition is for an aircraft like a Cozy with a specific mission - high speed travel.
The definition might well be different for an aircraft with a different mission - short field take off / aerobatics / crop spraying etc etc.

Regards,
John Slade
Turbo Rotary Cozy IV
87 hrs., all marginal.