impeller pitch what do they mean?

[stevethegas]

been looking at some props for my 98 gtx limited probably going to buy a solas dynafly but what do the numbers mean? eg 15/20

 

[Dr Honda]

Different companies use different numbers. Some use Degrees, and some use a rotational pitch. Also, when you buy a progressive pitch impeller, it can be a root/tip progression (to keep blade load constant) or it can be liner, to help create more pressure in the pump.

Because of that, it's hard to compare numbers from one company to another.

As I recall, Solas, and Skat-Trak both use degree pitch, at the outer blade edge. (Regardless of the root) that's why the Solas, and Skat-Track impellers perform differently.