Radiator and oil cooler info

[Terry Miller]

I'm wanting to replace my current large radiator with an oil heat exchanger, (26"x19") with a smaller radiator and an external oil cooler. I have not been able to find a short radaitor and heat exchanger. Any ideas on how to figure needs for cooling water and oil.

 

[Ken Shreve]

Terry,
If you post over on the prodracing site you should get your answer. All the Texas rotary guys run that setup.

 

[Terry Miller]

Thanks Ken. Good luck at Road America. Hope to race with you and Ernie next year.

 

[kyle_nickels]

Most important to overall size is the flow. A one row large tube aluminum has better flow and heat transfer than a 2 or 3 row copper. Unless your engine is making over 400 up you don't need a 3 or 4 row. In fact you would have to have a tight shroud and big pull fan to get air through a 4 row. Leave those for trucks. If it fits in the hole and has large tubes it will cool any engine short of a high compression or turbo/supercharged beast. The actual formula to determine the "correct efficient" radiator is very complex. Oil follows the same but you need to have a temperature control bypass valve ahead of a cooler to insure the oil is at the optimum temperature.

 

[HayesCages]

This help at all?

www.engineeringtoolbox.com/overall-heat-transfer-coefficient-d_434.html

LH

 

[kyle_nickels]

LOL doesn't help my head!! Rule of thumb I use is 1 square inch of radiator (1" tube - 1 row)per 1 cubic inch of engine size. 1/3 of that for a large tube and multiple row. I get into large diesels more than cars but find the rule works.

 

[DavidG]

If you are looking for an external oil cooler, I have a one off a 2nd gen rx-7 for sale here:

http://portland.craigslist.org/mlt/pts/2472639598.html

They can be used for 1st gens and other cars, and have the thermal contolled bypass valve that Kyle mentioned built in too.