Water pump impeller sizes?

2 sizes? I know of one in brass, and heard of another aftermarket that's plastic. Given housing dimensions, I don't think size is an option. I know that there's a difference in bearings and seal design between early and later.

 

See page 17 in section C of this document:

http://ferrari.cdyn.com/ferrari_docs/328_technical_specs.pdf

It gives the 328 water pump impeller diameter as 69.8-69.9 mm (which is the same diameter given in section C of the 308GT4 WSM) -- is yours a different diameter?

 

To my knowledge all V8 pumps are the same specification from GT4 to F40. There are different bearings, different seal designs and different materials for the impellers and housings even in factory pumps but they are all interchangeable.


Before believing you need a higher capacity pump to cool a modified or high output V8 remember the 500HP F40 and its racing counterparts ran a standard V8 pump.

 

along with a substantial radiator

 

The "large" bearing is 42mm outside diameter; the "small" bearing is 35mm outside diameter.