Oil Pumps

davidppp · 07-19-2007, 05:12 AM

hello all.

I recently bought what I was told was a GT2 pump, with a 996 part number.

What arrived was the old familiar 930 turbo Pump..., with its cast iron pressure stage.

Now my quastion is this.

What are the dimensional and material vairations between these newer pumps, and what types in fact exist?

I have heard of some exotic motorsport pumps..

Kind regards
david

Steve@Rennsport · 07-19-2007, 07:25 AM

David:

That "old" Turbo pump is a real dandy,.........

The latest 3 oil pumps that the factory used were the 930 pumps, magnesium 964/993 pumps, and aluminum GT-3R pumps with their additional scavenge pickups. These are all VERY close to being the same dimensions with the GT-3 ones slightly larger.

These all use the same short drive shaft. GT-3 pumps require some clearancing with Carrillo rods.

The very best two pumps are the 930 ones and the GT-3R ones since they both have the large pressure sides with the GT-3R ones having larger scavenge sides for very high RPM usage. The 930 ones hold a bit better hot oil pressure since the iron pressure side doesn't expand as much when hot.

davidppp · 07-20-2007, 01:54 PM

Thanks so much, Steve.

I know the Turbo is great..but wonder how much extra scavenge flow the GT3 has?

Kind regards
David

Steve@Rennsport · 07-20-2007, 02:59 PM

Hi David:

If I get a moment, I will measure the physical differences,.......

Grady Clay · 07-22-2007, 07:54 AM

The 930 pump measures:
Pressure – 50.5 mm
Scavenge – 28.6 + 50.6 mm

The GT3Cup pump measures:
Pressure – 50.5 mm
Scavenge – 50.92 mm
Center scavenge – 32.94 mm

Best,
Grady

Steve@Rennsport · 08:04 AM

Good man, Mister Grady,...

Thanks for posting that!!

If you use the GT-3R one in high RPM race applications, make certain that the scavenge plumbing is of sufficient size so you do not starve the thing at continuous operation above 7K. I've seen some folks use AN-12 which wasn't big enough,..........

davidppp · 07-22-2007, 11:17 PM

You guys are great!

I had wondered if the rotor diameter was bigger in the GT3 pump, but from the pictures I see it looks the same..right?

Grady and Steve, thanks, and thanks for the plumbing tip Steve..

Kind regards
david

Steve@Rennsport · 07-23-2007, 08:08 AM

Yessir, the diameters are identical.

911SCfanatic · 911SCfanatic's Garage

What is the torque spec for the oil pump nuts? Looking to clean mine and reassemble. TIA.

Grady Clay · 03:06 PM

I don’t think Porsche ever published those torque specs for the pump but regular M6 should be adequate with Locktite. Mechanical lock-tabs are also available.

The critical issue here is to check the gear-to-casting clearance. Plastigauge is a good choice. I have seen GT3Cup defective castings where there was un-machined excess clearance. I think every new pump should be internally inspected. 30-40 years ago that wasn’t an issue. It is today.

If I had the (life) time, I would build a test fixture to measure the volume flow / pressure of a pump at various rpm, temperatures and oil types. There Is No Substitute for actual testing.

Best,
Grady