912ULS High Oil Temperature

Can you talk a bit more about your setup? a picture would be nice, since it's a rather non standard.

Just a quick overview over my setup: I have a 912ULS with a rotrex compressor, to cool the whole thing I am using a laminova c43/180 with no restrictor, A thermo-bob thermostat and a Radiator of a Honda CB900F that is roughly 30% larger than the rotax to accommodate for the 8KW heat that needs to be dissipated from the oil. On ISA+25C days I get into the red zone after 5mins of climb (at 5500rpm and somewhere between 36 - 31 inHg MAP) and have to level off for a few minutes. anything below ISA+20C and I can climb without restrictions.That being said, I think you might have a problem with your airflow through your radiator. Since you were talking about probing the airflow, can you measure the differential pressure between front and backside of your radiator?

So long,

Tino

Tino,

Yes I can do that. I received a new radiator from Ikarus and it seems to have a little more cooling surface area. I couldn't try it tonight but I am hoping to try it tomorrow.

I will see what that brings me, then if I still have an issue, I will start looking at airflow inside the cowling. I agree in that it seems to be an airflow issue for certain

On my last annual, I replaced the oil pressure spring/ball and the bolt with a new spring/mushroom shaped 'ball' and bolt. No shims.

My oil pressure is 5.3 - 5.4 bar (~ 77PSI) and when the engine warms up at 4700RPM its 4.0 bar (~58PSI). Is this too high? My theory being high oil pressure = reduced flow = higher oil temperature. I may take it apart again to make sure I don't have the shim in there but I don't remember seeing one.

Also, I tried the replacement coolant radiator - little to no difference

58 psi is fine. Many have a little higher pressure right at start.

Flight report

Well. I removed the oil spring and it did in fact have a shim inside of the bolt. I replaced it with a new one I had ordered previously. The pressure did drop some, about 8PSI. I changed my instrument to PSI/DegF as well. I'm going to leave the pressure at PSI and the temps at DegC though in the future.

I put on the new radiator, and that 'oh this gasket between the cowl and radiator is essential' from Ikarus - In fact, I put 2 on there to make sure it was extremely sealed perfectly.

Outside temp -  76 degrees F
Climb from 680 - 2000 at 5300RPM, level off and cruise at 4700RPM - Oil temp 226F, CHT 217F Oil pressure 62PSI
Climb from 2000 - 3000, Level off at 3000 and cruise at 4700RPM - Oil 242F, CHT 232F (242f is 117C) Oil pressure 55PSI