I really haven`t found anything stating if they were mixed flow or axial. There`s not much info on them and really no support for them. The impeller slides onto the shaft from the back and the shims go in front of it so the wear ring is tapered to narrow toward the front so that you can tighten radial clearance by removing shims. The impeller is probably about 1-2mm smaller in diameter at the leading edge. On my ski-free it has a 428 cuyuna pushing it and from the factory the ski-free came with a 16/19 impeller. I found a NOS skat-trak that is 16/19 and was advertised as being too steep of pitch for the same engine/drive in the wet-jet trihull skis, it is a little better than the aluminum lump that was stock. The ski-free has plenty of power once it gets me up on skis, but its lacking while pulling me up. If I tie it to the dock I can rev right to 9000rpm, I think it is not loading the impeller well when stationary. I have not been able to get a tach reading while it is pulling me on skis because the tach was not happy with the 50' of wire extension to get it back to me. From sound it seems like the engine revs up fine when getting on plane the pump just isn`t moving enough water. I`m planning on trying a different tach next summer to see if I am running out of engine while getting up on plane or running out of hookup with the pump. However, I figured I would start comparing this to whatever pumps that I could find that are similar as I have a 2nd nozzle that I am thinking about doing some cleanup on. I`m also thinking about making a loader for the pump as there was never an aftermarket loader made. I`m fairly stuck with the drive cause I don`t want to do major mods to this thing as there`s only a few still running.
