Modine has a great step by step out on how to select an oil cooler.
It is 8
 meg so I can't email it but I did just upload it to the web site. I
suggest
 everybody download the pdf.

 http://www.rotaryeng.net/Modine-calc.pdf

 This is a real Christmas present for us as it takes some of the guess
work
 out of choosing an oil cooler that works.

 There is a some information you will need to know about the rotary.
 You will need to know the HP you are trying to cool.
 For that you need to look at this heat balance chart.

 I have modified the chart to make it easy for a 200 HP side port 2 rotor
 but
 if you have a  p-port two rotor you will have to multiply the oil
cooling
 HP
 number by 1.25. That means a 250 HP p-port engine running at best power
 mixture of 12.5 to one is rejecting 63 HP or 25% of the net HP out of
the
 engine to the oil.
 You then plug this number into the Modine equations to figure out the
 number
 of BTU's per minute you will be rejecting.

 The next thing you will need to know is the GPM of the oil pump
through the
 system. The stock number I think for the 2nd gen engine is 1.3 GPM at
1000
 RPM.
 At 7000 RPM it would be seven times that or 9.1 GPM. That number is
 somewhat
 dependent on the oil system plumbing and the size of the cooler. A
larger
 cooler with more tubes is going to allow the pump to flow a bit more
oil.
 Also right angles in the oil gallery of the engine also reduces the
flow.
 More about that later. Lets say it is 10 GPM for a 2nd gen oil pump.

 I think the 3rd gen pump is larger and the 3 rotor may be larger yet
but I
 have no hard data yet. You will probably need to make some assumptions
 about
 that.
 Perhaps someone on here has measured the 3rd gen pump oil flow. I think
 Mistral did that and I may be able to find it.

 Follow the first 3 steps in the pdf.

 Note the lower the Viscosity of oil the better it cools. Use Idemitsu
 rotary
 engine oil. I used to use Mobile 1 SAE 15 weight for 15 years but I
am now
 using Idemitsu. I think Mazdatrix sells it.

 In Step 4 you enter the Modine chart called Curve 1 and you pick a
LAB 130.
 With a LAB 130 you will get a very low oil pressure drop across the
cooler
 amounting to only a few psi. A Lab 130 core is about 22 by 22 by about 2
 inches thick. A smaller core will probably work as the airflow will be
 higher than what is called out in this PDF.

 Continue following the steps in the PDF to calculate the pressure drop.

 What is missing here is the airflow data.

 Paul Lamar

-------------------------------------------------------

From the 85 Technical data -
oil - 7L/min @1000rpm
coolant - 150-160L/min @6500rpm

IIRC, Al Gietzen? measured something like 15gallons per minute with a
20B pump @6k rpm @ 100psi.
One of the 20B owners may be able to confirm if the 20B pump has the
additional 3rd gen oil pump inlets on the lower side.
I have heard other dyno oil flow rates of 12-16GPM for 13B's.

Flow rates will, of course, depend on pump type(NA/T/3rdgen), oil type,
temperatures, filter, plumbing, mods...
Christmas Cheers
Cary

No telling what oil pump Al had as it was not a real 20B.
Atkins built it up from used 13B parts.

Paul Lamar