Quote:
Originally Posted by cnavarro
The IMS is located well below the where the oil level sits during normal operation in the integrated dry sump (i.e. wet sump).
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In this discussion we've tried to focus on facts and what has been proven through testing. I believe this view though that the IMS bearing is well lubricated without the seal through oil bath or splash lubrication is an assumption not based on actual testing. It would be pretty hard to measure, but I don't think the actual sump level has been measured through the dynamic loads that a car would see during normal driving. I would like to see any data that has been collected, if this has been done.
As such, I personally do not hold to this assumption that the bearing will see adequate lubrication with simply the seal removed. What I have seen, on the contrary, points to mediocre lubrication at best. Seeing is believing though and this is what I have seen, stolen from Feelyx on Pelican Parts:
The intermediate shaft sits up relatively tight against the engine case, allowing just a small slit for oil to get through to lubricate it from the sump below. Some oil will fall off the chain from above, but will still need to get through this small slit. This picture does not show the cover that would further block flow of oil through splash lubrication to the bearing.
Some more pictures of different views further illustrating this point.
So, would I depend on splash lubrication for this critical bearing? Absolutely not!
But what about oil bath lubrication? Maybe the bearing is partially submerged...
These photos from Feelyx again show where the oil bath is located. Obviously the chain was designed by Porsche to be lubricated by an oil bath. The IMS bearing was not.
So how much oil does the bearing get then if you just remove the seal? The truth is that we don't really know. LN Engineering "assumes" that it is enough. I personally look at the location of the bearing and I do not come to that same conclusion. Instead, what I am willing to bet on is having a good, consistent flow of oil directly to the bearing - direct oil feed. With DOF there is no guessing, no assumptions, you KNOW the bearing is going to get enough oil regardless of how much oil is in the sump and regardless of vehicle dynamics (hard braking, hard cornering, etc.). With a very expensive engine on the line and a car that I love, I am going to trust something that is a lot more certain and consistent - direct oil feed. This is why I've been such a big proponent of the DOF system - it just makes sense to me!
Kirk Bristol