Of course if the inlet tank is small, no thermostat in the system, full flow system, there is a small chance that most of the air gets pushed out!

Depends if the oil volume/mass that goes initially through the upper most rows of the cooler has enough inertia/speed to trapp the air and pull it along on the way down and out the bottom outlet ......

 

That is essentially my question!!

 

Is oil that much different than water that the outlet position does not matter??

 

I hope Lynn can shed some light on this - racing and all!!

It would also be interesting if someone has actual test/trial data:

# transparent tanks ....

 

My first rotary racer was an RX-2. The stock oil cooler was rotted out, so I added a GM air conditioning core in front of the water radiator with the inlet and outlet on the bottom. The cooler didn't cool and I asked one of the older guys what I had done wrong. Two of them agreed that I had installed the cooler upside down. I did not make the connection to the inlet/outlet location but assigned some magical happening in the cooler that would prevent its proper operation. I inverted the cooler, with the ugly hoses now in front of the water radiator

for all to see. And as if by magic, the oil level went down a quart and the oil temp was again below 200 degrees.

 

 Now how did that cooler know it was upside down? (I was a bit dull at the time)

So long as there is enough tube cross section to match the exit tube cross section, that is the number of tubes that will have oil flowing through them. The tubes above that amount will not be used, and will store air for ruining the bearings at a later date. Even air caught in the oil will stay in your new collection vessle/cooler. 

With the inlet/outlet on top, any air is removed at flow velocity. The solid slug of oil in the cooler cools better, and starts using all of the cooler. There was no magic.

 

I bought one of the thousands of Accusump oil accumulators for a Fiat race car. Bearings continued to fail, so the Accusump seemed not to work. The idea was that once charged to normal oil pressure, a reduction in line pressure (from a pickup being uncovered) would allow the spring in the Accusump to force oil into the system, to maintain oil pressure. 

 

I installed a tap and clear nylon line in the top of the oil storage section and ran that back to a cam box. I installed a shrader valve in the spring end, so I could charge the back of the piston with a bit of air pressure. After a few pressure cycles the amount of air from foam passing back into the cam box was amazing. The accusump would store up oil foam, until you needed it to operate, and then it would supply a whopping big dose of air to the bearings. 

The air bleed thing worked, and the accusump stayed in the car.  

 

Lynn E. Hanover