Another thread got me thinking about this. Two of my 968 engines arrived at my place with 2.5L pumps. One of which was my DD and for quite some time before a did a front engine job and put in a 3.0L pump, ran it with the 2.5 with no problems. So, what exactly is the difference between the pumps?

 

IIRC it's only the roller width that differs, the 16v engines have a wider timing belt.

 

The 2.7/3.0L pump has a larger impeller. The 2.5L pump will fit on the 2.7/3.0L engines, but not the other way around - I was told by a parts guy at Zim's that if you try to put the later pump on a 2.5L case, the impeller will contact the case and you may end up destroying both. My S2 had a 2.5 L pump on it when I bought it, too. I suspect that's fairly common - non-specialist mechanics doing a repair and sourcing the most widely-available (and cheapest) part.

 

Porsche part numbers show a part number 944 106 003 00 for 968
a late 944 is 944 106 021 24
most people use a turbo pump now 951 106 021 01or 08
I don't know what the difference is though.

 

Will have to look closely when I pull the 3.0 that's on the car and compare to a 2.5 on my counter.

 

What was the conclusion on this? Is there any good reason not to use 951 pump on 104mm block?