Water-cooled engines and oil pressure at track

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Water-cooled engines and oil pressure at track

Postby Greg Phillips on Tue Mar 14, 2017 11:15 am

There was a lot of discussion at Chuckwalla this weekend about oiling issues with the 996/986 & 997/987 engines and the oil pressure dropping during the long turns, especially right handers. My student's 996 C4 was under 2 bar of pressure n the 5-4 corner (CCW) :surr:

Here is a thread from Rennlist to review:
http://rennlist.com/forums/racing-and-d ... ers-2.html

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Re: Water-cooled engines and oil pressure at track

Postby Ryan McClune on Tue Mar 14, 2017 6:13 pm

Greg, I am glad you are bringing this up.

The car in question was mine.

I have an X51 baffled oil pan installed in the car, with no deep sump.

After this realization, my laps around that corner were done quite gingerly. :surr:
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Re: Water-cooled engines and oil pressure at track

Postby Cajundaddy on Tue Mar 14, 2017 9:49 pm

This is an issue that has been around for quite a while and the 986 Spec Boxster guys are keenly aware. It is not all water-cooled but is specific to 986/996/987.1/997.1 cars. All later cars beginning with 987.2 have much improved oiling and 4 scavenge pumps instead of only two for 986/996. They have proven to withstand the rigors of motorsport much better.

Lots of different methods have been used to mitigate the problem, some have worked better than others. Duncans use the accusump, some use the X-51 pan or deep sump pan. In running our 986 Boxsters for 10 years on the track we managed to avoid oiling issues with a few different methods. I can't say this will work for everyone but it did work well for us:
* X-51 windage pan
* 5w-40 syn oil.
* Make sure the oil level is topped off every day.
* Avoid high oil/coolant temps. (if coolant rose above 240F on the digital display, take a few cooldown laps or end the session) Hot thin oil is bad.
* Stay on 100tw tires and avoid higher G forces generated with 40tw tires.
* This last one is difficult for many to understand but I think it played a significant role in keeping our motors healthy at Chuckie and CFOS for many years including 100 track days: After a long sweeper, the pan is nearly empty of oil. As you get on the brakes entering the next corner, go clutch in and let the engine idle as the G-forces move forward. Now an easy heel/toe for your downshift and avoid a redline blip, just enough to get your gear. A heavy-footed redline throttle blip with a nearly empty oil pan will cavitate the oil pickup and kill a 986 motor quickly. Easy does it. We can't win if we scatter parts all over turn 3.

That is what worked for the Boxster Bros for a very long time, logging over 200 track hours on original 986 motors. If these things help you out, great. If you want to take a different approach, have at it.
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