pedsurg

Porsche has recently announced a new two piece crankcase for the next iteration of the 997. Additionally, the much maligned intermediate shaft has been eliminated. Is this design closer to our beloved dry sump blocks or just different ??

Eager to be educated, Jack
Tampa

NP993

All the 911 cases have been two-piece, or at least they all were through the 993, which is as far chronologically as my 911 knowledge runs. Here's one half a 911 case:

pedsurg

I believe that the previous crankcase (996 and 997) was four piece.
Jack

Bill Verburg

911, 964, 993, 996tt, 996GT2&3, 996Cup, 997tt, 997GT2&3, 997Cup, all have verticlly split dry sump crankcases.

normal 996, 997, Boxster et al have a horizontally split wet sump crankcase

normal 996 or 997, you can't see the internal crankshaft girdle and supports, above the c/c is a horizotally split p/p section








here you can see the c/s girdle



Gt3 or Cup, the c/c is 964/993 compatible

pedsurg

thanks bill. so what does the two piece crankcase mean for next year's 997. Does this represent a significant improvement ?? it sound like like a horizontal split vrs a vertical split makes a big difference.

Jack

pedsurg

Bill: Is the elimination of the intermediate shaft significant ?? It is reputed to be problematic in 996's; what about 993's ??

As always, thanks
jack

Mike J

There is nothing wrong with the intermediate shaft design as far as I know other than a tendency to have a bit of wear on it bearings. It is a bit of extra mass for the engine to turn but this shaft is used to drive both the oil pump and the camshafts. The design comes from the very early days at Porsche so it has to be good, right?

Bill Verburg

Both designs have an intermediate shaft

the wet sump IMS design seems to be flawed as there have been many issues w/ it
like this


The older dry sump design is quite robust and has had few issues. Eventully the bearings and gears will wear/

This is a dry sump IMS
[IMG][/IMG]

pedsurg

Thanks again Bill; keep the great pics coming. What can/should one infer by the elimination of the intermediate shaft n the 09 997 ??

Jack

pedsurg

So does this new case and the other noted changes represent a migration to the robustness of the dry sump system away from the "problematic" wet sump system ??
jack

Bill Verburg

Don't know, I'd have to see it. AFAIK direct injection is the big change and one of these days they will get the wet sump right. The 2 big issues since day 1 seem to have been the wetsump RMS and IMS

pedsurg

thanks Bill, so presumably one problem definitely solved (IMS) while the RMS issue remains unknown.

thanks again.
jack