Geoffrey

Here are a few pictures of the GT3R parts that I'm putting in my engine. The crank is a brand new unit and you can see it compared to a stock 964 crank. Some differences are that it has 180 degree oiling rather than 360 degree of the stock crank as well as being fully counterweighted whereas the stock is not. It is however 3.5lbs heavier.

GT3R oil pump where part of the case is cast iron as well as having an additional scavage port.

GT3R Crank in the background, 964 crank in the foreground


GT3R oil pump in the foreground, 964.993 pump in the background

bhensarl

Cool gear! Some questions:
-What are the benefits of the 180 degree oiling and counterweighting of the GT3 crankshaft?
-What's the benefit of the extra scanvenge port on the oil pump? Does it actually move a larger quantity of oil?
Brian

Cupcar

Geoffrey-

Does it look to you as though the main pressure section of the 996 pump is longer than the 993 pump and the scavenge section shorter? Or is is distortion in the photo, I haven't had both pumps in my hand to compare.

I think the advantage of the 996 pump is that there are actually 2 scavenge pumps built into where the 993 pump has only one. The new pick up is at the flywheel end of the pump where oil would naturally puddle under heavy braking. I think the 996 pump would have improved scavenging under braking and similar scavenging to the 993 pump when car sitting still.

Cupcar

BTW what is part number on that R crank?

Red rooster

Geoffrey,
Glad to see you got there with the GT3 bits. Price OK ?
Geoff

Dunasso

The additional weight will be offset by reliability factors, which will prove to be substantially more valuable on the track vs the savings of a few pounds.
Same could be said for the installation of safety equiptment.

Duncan

Geoffrey

I'm not really concerned about the extra weight of the crankshaft, it is lighter than a 3.2/3.3 crankshaft which it is more similar to than the 964 or 993 cranks. The weight will also be offset by the lighter pistons, connecting rods, 5.5" Tilton clutch and lack of the heavy vibration damper found on the 964 crankshaft.

The 180 degree oiling design allows for the connecting rod bearing to be oiled every 180 degrees rather than every 360 degrees. In other words, there are two oil holes in the crankshaft every 180 degrees rather than a single oil hole at 360 degrees.

The GT3R pump has a larger secondary scavage pump and has the benefits already mentioned.

sundog

Geoffrey, are there any case mods required for the gt3 oil pump? My pump is gone, and the gt3 pump is cheaper than the standard 964 pump, so jerry woods recommended I get the GT3 one.

Indycam

Item number: 4564087334
Item number: 4616309172

Geoffrey

There is a web on the case half that needs machining so the secondary scavage clears.

Indycam

Hiya Geoffrey
What do you think of an external oil pump set up ?

Geoffrey

I think the Porsche oiling system works just fine as it is.

Red rooster

Geoffrey,
The GT3 crank has what we used to call crossdrilling on the big ends ? It would maybe possible to drill a 964 crank the same way ??
Surely both cranks are fully counterweighted ? though the GT3 weights are bigger .

All the best

Geoff