Thread: SHO/FZR pump vien blowouts
06-02-2010, 09:32 PM #1
SHO/FZR pump vien blowouts
Ever notice how these things blow out in round-style holes around the edges?
Ever seen a STOCK ULTRA250 pump? Note the round holes in the leading edges of the pump.... Pre-relieved.
There is a hydro-lock happening on the leading edge of these pumps between the blades and pump. You might as well take a hammer and smack your pump over and over till it breaks.
This isn't cavitation... this is good ol' fashion hydro-locking. Cavitation will boil SST just like aluminum, only slower.
These damaged pumps are pressure damaged... or if you will, "self-relieved."
A wise tuner might equally relieve his HO/FZR/SHO pump in the EXACT area about the size of a quarter on each blade, and clean up the area afterwards.
06-02-2010, 09:44 PM #2
makes sense. has anyone tried an ultra pump conversion on one of these? with the roots blower i would imagine that the ultra has the most torque out there
06-02-2010, 09:49 PM #3
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06-02-2010, 09:51 PM #4
06-02-2010, 10:07 PM #5
06-02-2010, 10:13 PM #6
It doesn't prevent cavatation but simply the inevitability of things to come. JMO.
06-02-2010, 10:19 PM #7
I always wondered why the kawi pumps werent used more often in conversion skis. They seem pretty ahead of the game in that area.
06-02-2010, 10:20 PM #8
So, having this happen is not necessarily the end of the pump?
What impact does having these 'reliefs' have on the performance of the ski/pump? I am assuming this is essentially a band-aid? Something I am tired of doing if possible...
06-02-2010, 10:40 PM #9
Found one of ours on Saturday with 2 veins damaged so i continued and did the rest and cleaned them up. Tested it but not finished testing, I want to try a couple of prop combos to be sure.
The ski was faster though.
06-02-2010, 10:44 PM #10
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