My limited understanding was/is that the fear in high oil temps was permanent set in the side seals.  Didn't get the pan oil temp for the lack of ‘paging’ of the monitor screen. The oil pressure was about 85 psi. What sort of alloy of indium is used on the bearings?

 

You can reduce oil temps by limiting throttle settings. A slight reduction can make a big difference. Also reduced ignition advance and richer mixture settings help.

 

The mixture during full power climb was lean – O₂ sensor at the bottom of the scale.  The pilot didn’t recognize the need to tweak the mixture knob, and the MAP was a bit higher (~1” hg) then I had ever seen on static due to the dynamic pressure of the ram induction scoop.

 

Al

I have never seen a side seal fail due to anything. They do get damaged during other misadventures. Alloys of lead and indium and maybe aluminum are all used by various MFRs

for the top layer of their bearings. Racers use the race bearings with .0005" extra clearance or machine away the overlay and run on the copper substrate. The overlay is just under .001" thick so the extra clearance is just right. Copper is a very strong bearing material, but less forgiving of dirt particles than the indium.

 

A more typical take off power setting would be full rich. A Continental O550 might use 32 GPH for take off and then cruise lean of peak at 13 GPH or even less. The cylinder head temps must be seen to be believed. Properly operated engines, even those "piston ones"

can actually go to overhaul with the original cylinder still on them. 

 

Just going richer might be enough to get the oil temps under control. If the high temps are just from take off and climb, then a water spray on the oil cooler might work just fine.

 

Running a little bit lean of peak EGT will not hurt anything but will raise operating temps. Both oil and water.

 

Cruise should be more lean yet so that the percent of full power is a function of fuel consumption. The rotary will run almost 200 degrees lean of peak EGT, and how close is a function of the ignition system performance and plug gap. Of course the amount of power is also way down along with fuel consumption. Mixtures well lean of peak are also very cool running for water and oil temps. Simple, Less heat from less fuel = less heat.

 

Lynn E. Hanover