08-10-2009, 04:16 PM #1
Stage 3 question Pitch the prop or get a different prop?
I GPS'd my Stage 3 today and here are my results, 77.0 air temp 90* H2O temp 68* I did 4 passes and never could get over 77 mph. My RPM's were right at 8600. Heres my setup, Riva ECU, 4" Kana with a Spectre, Rude 1, 50# injectors, RRFPR, Riva/Sea Doo external IC no BOV, Green Hulk water box, catch can, Riva wedge, Riva/Skat 15/19 swirl, SS wear ring, and Pro Series reduction nozzle with the 81mm ring. Soooooooooo it seems to me I'm being limited y the fact I'm on the rev limiter, should I repitch or try a different impeller?
The kicker is my 07 stage 2 which is almost set up the same, other than a Solas 15/20R, Pirhanna IC, Green Wheel, 42# injectors, no Riva ECU or reduction nozzle runs 75.2 GPS MPH on the same exact course, same weather/conditions 10 minutes later Whats up???
08-10-2009, 04:23 PM #2
The impeller is whats up ... put the Solas 15/20 4 blade in there and see what happens ... rpms will drop and speeds will go up.
08-10-2009, 05:21 PM #3
08-10-2009, 06:15 PM #4
I don't know ... I have had both ... ran 78 mph with the 3 blade, and 81 mph with the four blade ... the three blade may be a little quicker out of the hole, but the four blade stayed on my ski. My friend Dan and I ran side by side with virtually identical boats and even tho the 3 blade felt faster, it was not even worth a full boat length in acceleration compared to the four blade. Just my experience, others may differ ...
08-10-2009, 10:35 PM #5
08-11-2009, 07:58 AM #6
- Join Date
- May 2005
You likely will not see much over 78-78.5 mph with that setup. I would go to the 82 mm ring, have .5 degree added to the leading edge and have .75mm added to the trailing edge. Send the prop to Skat to have it progressively pitched the proper way. That should drop you 150 rpms net. You should end up at 8500 rpms with better acceleration.
08-11-2009, 09:41 AM #7
Your setup with a 15/20 or 15/22 4 blade and the right ring to get rpms to 8500 range should get you 82+ mph. Some have run 83 - 84 with that setup dialed in with a good 4 blade.
08-11-2009, 11:04 AM #8
08-11-2009, 02:01 PM #9
Since you have the nozzles and a Rude1 I would go with the 15/22 ... we have found that the 83mm nozzle is not necessarily any slower than the 81 or 82 on your setup when the rpms are right ... you could run either, but usually a larger impeller is faster even if it has to be pulled back slightly.
08-11-2009, 09:26 PM #10
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