Replaced radiator, now the engine is running hotter during stop and go driving

quote:

Originally posted by ZR1 Pantera:
Most of the Fan companies recommend a pull configuration and have stated that a pull style fan with a shroud is more efficient than a push style fan. This is why the MAJORITY of radiator fans you will find are in a pull through configuration. Almost every single Ron Davis Radiator is configured as a pull through. They do every motorsport on the planet including NASCAR.

I suspect your car runs cooler with the pusher fans on, simply because of the additional airflow of all three fans.

For an accurate test, you would need to run with a single or dual pusher fan ONLY. Record the results. Then run with the same single or dual fans but in a puller configuration and record the results.

The proper designed puller configuration with the proper shroud is the desired configuration. HOWEVER, if there isn't enough room for a good puller configuration, then a good pusher configuration may indeed win...

I think the feeling is that draw through fans are more efficient because placed behind the radiator the motors and fan assemblies do not block the flow of air through the radiator core when the car is on the move (which is true). But most race cars don't spend much time sitting around idling in traffic.

I think you could be quite correct in that my engine runs cooler with the pusher fans on because of the added airflow of all 3 fans. But keep in mind they are pushing hot air from the condenser into the radiator. I should test to see what happens when i run with the 16" draw through disconnected, the a/c disconnected and the two 9" pushers running. So there are just two pushers moving cool air into the radiator.

This has been a big debate in the Heating,Ventilation and Air Conditioning industry for decades.

What is best forced draft or induced draft ?

The answer was generally whatever fits neatly into a given design as it is possible to get both set ups to work.

I was considering if Slojoe could re-use the fans he has already bought in a configuration that gets more out of them rather than forking out for even bigger fans.

Just an idea.

quote:

Originally posted by ZR1 Pantera: Most of the Fan companies recommend a pull configuration and have stated that a pull style fan with a shroud is more efficient than a push style fan……The proper designed puller configuration with the proper shroud is the desired configuration. HOWEVER, if there isn't enough room for a good puller configuration, then a good pusher configuration may indeed win...

Fully agree. If the discussion is limited to just the air/flow heat rejection portion of the cooling issue, draw through systems with good plenum design almost always win the low/no forward car speed contest because they are able to more uniformly draw air across the entire radiator core whereas a pusher concentrates the air in a circular pattern. Contrary to popular belief, these axial flow fans don’t really create pure axial flow. There is a significant radial flow component and this coupled with their close proximity to the radiator core makes for higher pressure drop and lessens efficiency. For a puller/plenum, the pressure drop on the suction side is usually less pronounced because the area of a pair of circular fans is still usually ½ or less the projected area of the core. Pullers should be spaced off the core as far as packaging constraints allow but an inch or two is usually sufficient to get most of the benefit of compromise.

When you transition to high forward car speeds the issue with a puller/plenum configuration becomes you only have half the exit area through the two circular fans as you have radiator core area. So many people incorporate flapper doors on the plenum that open at low pressure differential and provide maximum cooling potential at speed. This is usually only required for high power and sustained use of such or extreme environmental conditions. I’d say for 90+% it’s not necessary to resort to such and the cooling issue is likely manifesting itself elsewhere in your cooling system.

There are other threads on the forum which further document and describe this topic.

Best,
K