Yes, not optional for endurance racing rotaries. It is also why so many rotary powered LeMons cars fail with almost 100% certainty.
We cooked more than one PP rotary when this all began. This had to stop if we were to have a reliable LeMons racer again. The advise from the local self exposed "experts" turned out to be car folks who practiced out of hear-say rather than factual knowledge about the rotary. To gain a proper understanding of how the rotary works, some study of SAE papers published years ago by the folks from Mazda had to be done and many long discussions with Jim Tanner at Racing Beat in So Cal. Essentially, the cooling of a rotary happens with just over 50% from the oil and the balance in coolant. Max operating temperature for reliable operation of any Mazda Rotary is 200 degrees F for BOTH coolant and oil. Exceeding 200 degrees F will rapidly degrade the housing O-ring (PTFE backed silicon with a special joint) and the EPDM coolant passage O-ring. There are feed tube O-rings that also die when the max operating temp is exceeded.
This Mazda 12A peripheral port rotary idles at about 2,500 RPM, make no significant power unit about 4,500 RPM then power peaks at about 9,500 RPM at 200+ Bhp & 150-170 lb/ft torque. Power band is pretty small. This much power produces a LOT of heat that must be expelled, Have a good look at any serious rotary endurance race car, they will have oil cooling equal or greater than the coolant. The rotary powered LeMons X is run on hot summer days at well over 100 degrees F at full throttle hour after hour. This is why there is so much oil cooler with a fan. The stock exxe cooling system is not a problem for ambient temperatures of 100 degreed F. Typical oil temps running full till at a LeMons race in 100+ degree heat is 180-190 degrees F, coolant temperature is about the same. Any more, we got serious trouble.
We also run a cooling system for the driver's cool suit during hot summer races. Keeping the driver's cool is imperative to get the best out of the drivers and keeping then from making mistakes while driving that could be bad to horrific. Two hours in the driver's seat of a race car on a 100+ degreed F is really stressful, anything to reduce this stress is good.
After the cooling systems got sorted out, the current PP rotary has about 100 race hours on it problem free. This PP rotary is now due for overhaul-service. The newly built PP is ready to be installed, run in then raced. Soon after that, I'll take the current PP rotary apart and make it good again. This was another notch in running a rotary powered race car, learning how to produce proper, durable-reliable PP rotary race engines. They are different from piston engines but the same technical requirements apply.
So yes, if there are questions about racing rotaries ask.
Bernice
Bernice,
Does a rotary race engine always require this much oil cooling capacity?
