impellers

[thrillseeker]

Hi Huy's, can anyone tell me which is the better,three or four blade impeller for higher HP engines. Would the three blade create more slip or less. Any info. would be appreciated thanks

[JR]

Hi Huy's, can anyone tell me which is the better,three or four blade impeller for higher HP engines. Would the three blade create more slip or less. Any info. would be appreciated thanks

I can only tell you about my boat... Started off with a 4 blade 19 and then i put a Southern Jet 3 blade in and it was Clalk and cheese ... The 3 blade was the !t... If you want the root out of the hole go for a 3 blade and good mid end punch.....
 But you can get a blade made for any engine... It is a big world out there... And if you want to spend the dollars..
Cheers JR

[thrillseeker]

Thanks JR yea pretty muck what I want to do. Get from A to B quick but keep the RPM around 5000to5200 which is where the power band is. Saw some S/S three blade Scott impellers on Trademe. Thought They might do the job but I have no experience with three blades to know what would happen.Currently using four blade 21 deg but still getting slip on full acceleration out of the hole. Budget a bit tight at mo so have to experiment with what I've got with a bit of repitching I think.

[Karl]

If your blade OD's are correct, then try a smaller nozzle insert.

[thrillseeker]

Hi Karl, Thanks for that. Yes done all that, couldn't get ODs much tighter. and tried nozzle sizes but I just can't seem to get enough grip. I was almost there a while ago with an ex. sprint boat impeller but found too many cracks in the blades to be safe. So hence looking for a better option.

[Karl]

Whats your setup, engine/unit/hull etc .

[thrillseeker]

Well, where do I start.without going into too much detail the Hull is a home built copy of the old King Craft Sprint hull, Motor is a modified 383 Chev, Unit is a modified two stage. Boat mostly used for club comps. and sprints etc. Have done well with this setup in the past but trouble started when the new 383 went in. Probably a bit too much for it. Anyway I'll keep experimenting with impellers I have until I get there.

[Kenjet]

Scott bullet blade brought revs back from 5000rpm at WOT to about 4200 with no slip when we reconditioned our 308 in an HJ 752 unit. As you say 383ci probably too much grunt for an older model 2 stage .