964 Oil Pump- Specs, but what RPM

944s4me · 944s4me's Garage

According to BA (Page 64); the 964 pump delivers 65 liters of oil per minute and the scavenge pump has 1.84 times the capacity of the pressure pump.

At what engine RPM are these rated specs ?

65 liters (volume) per minute for the pressure pump.
119.6 for the scavenge pump.

65 liters is roughly 68 quarts that the pump will be able to potentially pump at the relief valve pressure per minute.
The scavenge pump has the capacity to move 125 quarts , 31.25 gallons which is a gallon per second, and there is no relief pressure valve.

I have a 964 pump in my motor, and want to make sure the oil thermostat and the oil cooler / cooler lines have enough volume capacity to handle the potential volume output.
I know some of the scavenge volume will be air which can be compressed.

I want to avoid trying to send more oil from the scavenge side of the pump than the lines, thermostat, cooler and static losses can handle.

Any help and or, real applications that have worked is appreciated.

stownsen914 · 10-29-2020, 12:47 PM

If you are doing aftermarket oil lines, it will probably be best to use -16 size lines, and make sure your cooler, thermostat, etc. fittings are that size as well. Some say -12 is sufficient, but I say once you're doing custom, do it right. Re: cooler selection, cooling capacity is very important. If you post the intended use for your car, you'll get some opinions. Front spoiler mounted/ducted will be most efficient for cooling.

winders · 10-29-2020, 12:59 PM

There is no way -12 is sufficient for an engine run hard. People may get away with it....but you need -16 all the way around....and a -20 on the feed line is not a bad idea although not required.

Walt Fricke · 10-31-2020, 07:52 PM

I've never had an issue with -12 on the scavenge lines up forward. And coming back, if you are using the stock oil tank. -12 is very close on the ID of the stock metal lines for the front cooler and thermostat, and of the fitting screwed into the case where the oil comes out of the scavenge pump.

There would appear to be two aspects of this. One is will you starve the engine of oil using -12 lines for the pressure side of the scavenge oil. The answer there is no.

The other would be the effect on parasitic losses. I think the analogy here is to resistors and wire resistance. The outlet from the case is one resistor. The lines themselves have a resistance. And so does the cooler, and the thermostat. A wider line should have less resistance, but the issue here is just how much? Is it enough to cause the pump to absorb one more horsepower or foot pound of torque? A hydraulic engineer probably could calculate the difference in friction (or resistance or whatever parameter is involved) per linear foot between -12 and -16 and come up with some back of the napkin figure for X feet of line.

The return line from a front mounted oil tank is a different matter. I am dubious that you would get starvation from a -16. As long as the pressure side of the pump never lacks oil, all should be well, shouldn't it?

The roller race car I bought had -10 on the scavenge line, and -12 on the return from a front mounted oil tank. Had worked for the previous owner, though the car ran a 2.0 I believe in SCCA

winders · 10-31-2020, 08:56 PM

Go ahead and run -12 lines on an engine using a 964 oil pump. Don’t blame me when it is ruined because of a lack of oil.....

targa72e · 11-02-2020, 12:37 PM

You don't even need to do any engineering. There are plenty of online calculators were you can look at flow vs diameter vs length. Example below:

https://www.copely.com/tools/flow-rate-calculator/

What you can see is that hose diameter becomes much more important as lengths get longer.
Also important to take into account the size of some of the smaller point in the system.
For example the inlet to the pump from the tank in the case is only .7" (this is the same on mag case 2.0 and the GT3 case I have as well) The oil cooler pump inlet where it meets the case at this point is only .67"
The steel line from a SC on the scavenge side that attaches to the case has a ID of .75"
Early oil tanks with filer consoles have a diameter of .54" at the filter attachment (later OC54 filters have a larger inlet)
So larger diameter lines become more important the longer the hoses. Race car with front mount oil tank needs larger lines than stock oil tank in rear.

john