Quote:
Originally Posted by Cupcar
FWIW - Porsche went the other way with their parts supercession for 3.6 engines, the small hole 964 connector piece has been superseded to the large hole part of the 993 for both 993 & 964
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Just need to be sure everybody understands that the pieces Cupcar refers to above are not the same part as those used on the older cars. They serve the same purpose (oil feed from crankshaft/case to cam housings) but they are a completely different part, typically referred to as a "bridge."
Basically how it works, the 964 oil system was modified to integrate the old, external cam housing oil feed hoses on the pre-89 engines into the cam chain housing. The chain housing actually has oil from the crankcase pressure circuit running thru it to supply oil to the chain tensioner and also supply pressurized oil to the camshaft housing via the aforementioned bridge piece.
All that being said, the 964/993 bridge and the older style cam housing oil feed adapters/restrictors serve the same purpose- get oil to the cam housing. If an orifice within either of those parts is modified, the oil supply to the rockers and cams is directly affected.
To add a bit to what Alfonso said, yes the 964 oil pump was upsized. It is larger in physical size/pumping capacity (both scavenge and pressure) than the 3.2/3.0 pump but not as high a level as the bad boy 930 pump. It looks a lot like the 930 pump but the giveaway is its magnesium body vs. the 930 aluminum and iron combo.
964 also has larger piston squirters (2.0mm orifice vs. 930 1.5mm vs. "normal" 1.0mm) and it has a shim/spacer in the vertical pressure bypass valve in the crankcase.