JoeMag

After needing to do a little motor work this winter I decided to upgrade the 964 oil pump to GT3. This required machining down one of the main webs for the secondary scavange (first pic). I used play-dough on the web to confirm clearance by putting the pump in the case and measuring the depth of the playdough which stuck to the pump when I removed it. An interesting thing that I found out is that the RS, RSR, and GT2(?) cases have a counter sink in the first four main through bolt holes (see pic with pump installed) for an O-ring install in between the case halves. I'm not exactly sure why, but have heard that was to minimize resonance vibration of the through bolts in the holes that do not have oil in them.

trophy

Interesting that are still using the casting for the GT3 pump from the 930, (just below the playdoh).

Looks like you will be stup for the coming season.....

JoeMag

Wow, this oil pump definately makes pressure. Had the car at the track few weeks ago and the 1 bar per 1k rpm doesn't hold. At idle (~1,500 rpm in my car) is make ~55 psi (almost 4 bar). I'd have to look at the data again, but I think by ~3k rpm you're max out on the regulator spring (~90 psi, 6 bar).

chris walrod

Good result!

Yes, those counterbores are to help mitigate case through bolt vibration.