prop bending 101

[Quinton Robbins]

Impeller tweaking question.

If you build back the OD of a impeller that "shrank" from re-pitching; Could this decrease RPM?

More specifically prior to building the OD the impeller in question (14/29) had a clearance that grew along the length of the blade. Starting at. 014" (per side) growing to .095" or more (per side) at the trailing edge due to re-pitching.

After rebuilding and machining there is now only. 004" clearance per side along the full length of the blade.

Should this cause a noticeable drop in RPM?

[beerdart]

Wear ring clearance should not affect RPM (Within reason) but it will affect cavitation.

[Quinton Robbins]

Cavitation is now near zero which was my goal in building to OD back.

[FZS-RIDER]

i must make all the vens on the line ? or just first of the impeller ?

[prostocker]

I'm selling prop gauges just in case anyone is interested thank you..

[Speedling]

Figured I would post this question here instead of creating a new thread....
Why would the dynafly impellers be any different than the rest when it comes to the repitching?
I have a 14/20 dynafly, and I was going to be moving it to a 14/21, or 14/22. Is this little enough to not worry, or am I messing with things I shouldn't?
Thanks guys!

[prostocker]

Figured I would post this question here instead of creating a new thread....
Why would the dynafly impellers be any different than the rest when it comes to the repitching?
I have a 14/20 dynafly, and I was going to be moving it to a 14/21, or 14/22. Is this little enough to not worry, or am I messing with things I shouldn't?
Thanks guys!

What do you mean they are different ? at what rpms you are and what rpms are you trying to archive.

[fzs13]

Thanks for the info!

[WFO]

Figured I would post this question here instead of creating a new thread....
Why would the dynafly impellers be any different than the rest when it comes to the repitching?
I have a 14/20 dynafly, and I was going to be moving it to a 14/21, or 14/22. Is this little enough to not worry, or am I messing with things I shouldn't?
Thanks guys!

Dynaflys grow in diameter when pitching trailing edge up, so the diameter must be re-cut for clearance. When de-pitching they will pull away from the liner, and usually involves rewelding to get air gap correct.

Before pitching you should get good baseline rpms numbers

[Speedling]

Figured I would post this question here instead of creating a new thread....
Why would the dynafly impellers be any different than the rest when it comes to the repitching?
I have a 14/20 dynafly, and I was going to be moving it to a 14/21, or 14/22. Is this little enough to not worry, or am I messing with things I shouldn't?
Thanks guys!

Dynaflys grow in diameter when pitching trailing edge up, so the diameter must be re-cut for clearance. When de-pitching they will pull away from the liner, and usually involves rewelding to get air gap correct.

Before pitching you should get good baseline rpms numbers

I think I understand.... Adding pitch should be ok if it doesn't rub. What I don't understand is why would other impellers be fine and this one isn't.

As for the RPM's, I have one engine at 10,200 rpm and the other at 9800. I plan a couple more small mods to see how it runs, but was hoping to get them to redline, then pitch it a bit more for the speed.

[WFO]

Figured I would post this question here instead of creating a new thread....
Why would the dynafly impellers be any different than the rest when it comes to the repitching?
I have a 14/20 dynafly, and I was going to be moving it to a 14/21, or 14/22. Is this little enough to not worry, or am I messing with things I shouldn't?
Thanks guys!

Dynaflys grow in diameter when pitching trailing edge up, so the diameter must be re-cut for clearance. When de-pitching they will pull away from the liner, and usually involves rewelding to get air gap correct.

Before pitching you should get good baseline rpms numbers

I think I understand.... Adding pitch should be ok if it doesn't rub. What I don't understand is why would other impellers be fine and this one isn't.

As for the RPM's, I have one engine at 10,200 rpm and the other at 9800. I plan a couple more small mods to see how it runs, but was hoping to get them to redline, then pitch it a bit more for the speed.

the root on the Dynafly is different from other solas impellers... if you pitch up correctly, you will have to cut the diameter

[Just-Pinch-It]

Is cavitation during the holeshot best adressed by increasing the leading edge pitch? And, if the leading edge pitch is increase by 1-2*, how much effect will it have on decreased peak rpm?

[Speedling]

Is cavitation during the holeshot best adressed by increasing the leading edge pitch? And, if the leading edge pitch is increase by 1-2*, how much effect will it have on decreased peak rpm?

Well, are you having cavitation ONLY on hole shot, or all the time? You can degrease the leading edge to get a better hole shot I beleive. Meaning, going from say a 14 leading edge, to a 12, would/should give more bottom end.

[modblaster]

I want buy a gauge prop for seadoo 140mm ? How much

[prostocker]

I want buy a gauge prop for seadoo 140mm ? How much

$50 its on my signature pm sent