Oil cooling a Rotrex necessary?
 

Hi,

I'm torn back and forth. After I ordered my C30-84, Rotrex told me that a oil cooler is usually not necessary for a C30, according to their experience. For a C38 always.
When I look around, everybody in the miata world uses a oil cooler.
Has anybody done some measurements of the traction fluid temperatur after a hot lap?

Beluci

At something like $100/liter, I wouldn't risk over heating it. Every kit I've seen includes an oil cooler. That gear drive spinning constantly at 10,000 (100,000?) rpm is going to generate a lot of heat, regardless of engine temp/track driving.

TDR and Kraftwerks both include a rotrex fluid cooler in the kits. TDR going bigger and changing the mounting location compared to KW's kit.
https://kraftwerksusa.com/products/b...rcharger-kits/
https://trackdogracing.com/Rotrex-18NB.aspx

Whose rotrex kit did you buy that doesn't have one?

No kit, just the blower for now. I will do the kit by myself.

Why not cool it?

I am very surprised Rotrex said "it would be OK". They are pretty particular about the oil cooling system in their technical leaflet.

Because simplify and lightness :)

If it's not necessary, it's a waste.

Their argument was, not to take the additional risk of leakage.

In their technical handbook, Rotrex mentions that oil should not exceed 80 deg. C, so I guess you could test your system and add an oil cooler if necessary, stating that higher inlet oil temperature will damage the supercharger.

On every explanation/figure of the oiling system, an oil cooler is present, and on to of that the oil canister is finned to "act as a secondary oil cooling element", recommending to install both in air flow. They also insist quite a lot in using their standard oil circuit components, stating that you should "consult your distributor or Rotrex if you need to modify the standard oil set in any way (even if the change seems trivial)", that's why it seems peculiar to me they suggested to run it without a cooler.

To me, risk of overheating >> risk of leakages/additional potential failure points, so I would run a cooler.

I heard from the traction fluid gets more heated at idle than at higher RPM’s. Something to do with slippage at low RPM’s vs full engagement at higher RPM’s.

Based on my experences with how hot the oil cooler gets just idling I would not risk a $2k compressor on an experiment.

I have one one of the early style mini coolers and it seems to keep everything happy.