I started to post this as a reply in the "Causes of M97.21 Engine Failure?" thread, but that thread is pretty long in the tooth, and is (was?) really focused on discussing the causes of engine failures. There is information about various modifications sprinkled through it, but I thought it would be useful to assemble people's experience with different solutions in one place. So...
For new readers on this topic: the issue is lubrication related engine failures in Cayman/Boxter gen 1 engines, brought on by high lateral g conditions. This usually (but not always) means a modified car (suspension, sticky tires) on a track, and is particularly problematic with sustained high g left hand turns. The "Long Version" is available at the thread referenced above. Causes of M97.21 Engine Failure?
I'm getting ready to move to R compound tires, and I think it would be naive to do so without trying to make the engine more reliable under high g conditions. The question is, what modification to make???
I'm taking a pragmatic approach to the problem: I don't need to solve the design issue (though it might be an interesting exercise). Rather my goal is to solve my immediate problem: this engine model seems to have an history of failure under conditions to which I may very well subject the car. So my goal it to find the best way to reduce the risk of engine failure, and I really only care about effectiveness and cost. I think most members are probably of the same mindset.
Of course, understanding the underlying problem would help significantly in assessing modifications. This is my frustration with Porsche, since they are by far in the best position to provide meaningful data about the failure mechanism. I don't mind spending some money to upgrade the reliability of the car for track use, but some guidance on effective modifications would be nice. Alas, Porsche has made their position clear and we get no help.
So it seems there are a few known options out there people have tried:
As far as I can tell, this is a remote accumulator that will theoretically help maintain pressure in the oil pump discharge line. If properly configured, it should probably be able to cover for brief periods when the oil pump is not maintaining pressure (perhaps due to no oil at the pickup, or highly aerated oil at the pickup). I would need to work through a diagram of the oil system and how the accusump connects to be sure.
- Probably $1500-$2000 depending on the installation
- Straightforward install but need to find a location for the canister
Auxiliary scavenging pump that appears to draw oil from the front of the right side cylinder head and return it to the sump. Theory seems to be that oil accumulates here, particularly during left hand turns, and the stock scavenge pickup is not effective in removing it (because it's too far to the rear? doesn't have sufficient capacity?). Again, it would help to better understand the oiling system to assess this approach. Some people have reported great success with this system, including people who race the cars in Europe. Also I believe Porsche has offered a similar modification kit for some engines in the past.
- Very Expensive: probably $3000+ to install
- Porsche will immediately void your warranty if this is installed (which is a risk anyway if the car is tracked)
Deep Sump / Windage Tray
I'll put these together since the setup I think looks most likely to be effective is the Mantis extended sump / windage tray combo. Seems like it should help in two flow directions since the tray is mostly closed: (1) oil below the tray (and at the oil pickup) should be less aerated since the heavier, better flowing liquid will drain down through the tray and baffle trap doors more readily than froth, and (2) the limited open area should act to dampen the lateral shifting of oil in transient high g turns. [In a sustained skid pad session eventually the oil would reach an equilibrium angle in the sump and it would not help, but in typical road course transients it seems it should slow the migration of oil side to side. I do wonder whether any science or testing went into the area and location of the holes in the windage tray, or if they just guessed...]
This probably only delays the onset of the problem, but may be sufficient for typical road course transient conditions. Seems it should help at any rate. Wish I had a good way to test it....
- Simple install; probably a 2 hour job
- Relatively low cost (<$1000)
Has anyone tried other modifications with any success?
What about people's experience (success/failure) with these?