Thread: My Red Ski a GPR-SHO
08-17-2010, 10:26 AM #1
My Red Ski a GPR-SHO
In the never ending quest for performance I have started working on a GPR-SHO platform. Thanks to all those that have helped me along the way. Special thanks to those that have helped me with this specific project, which is my first 4 stroke ski (Duke, Hydrotoys, 2fast4u, Desparodo, WFO). These 4 strokes sure are a lot different from the 2 stroke motocross bikes I grew up with as a kid.
The Boring Stuff
2004 GP1300R hull
R&D CF tunnel reinforcememt
WFO intake grate reinforcement
IR pump tunnel and rideplate reinforcements
UMI steering stem and bars with Odi grips
Hydroturf mats and side lifter wedges
Hydroturf seat cover
2008 SHO motor
Riva E1 wheel
Dedicated IC water feed line and bypass
R&D Multi-Pressure Port Boost Gauge/Surge/RRFPR Adaptor Kit
Rising Rate Fuel Pressure Regulator Kit
R&D R2 ECU Reflash
The Interesting Stuff
GPR Injectors - (SHO injectors flow 396 cc, GPR injectors flow 552 cc)
Fuel pressure set at 48 lbs, rising rate turned off
R&D Powershot used to fine tune fuel at WOT and to prevent MAP sensor errors
Fast Air/Fuel meter with RPM logging module
Heat sink for oxygen sensor in high heat apps (037)
NGK Racing Spark Plugs R7437-8 with 0.027" electrode gap
The Innovation - All sorts of new parts!
Seadoo Pump Adapter - I made my own Seadoo Pump adapter which is designed to allow the Seadoo RXP pump to be used on a Yamaha hull.
Nozzle Adapter - Most previous Seadoo pump installs have used the Seadoo nozzles. I wanted to use the SHO pump nozzle because it is on a 5 degree upwards angle which is ideally suited to the GPR hull. It didn't make any sense to me to use the 0 degree RXP nozzle. Also if I was to use the RXP nozzle I would have had to drill another hole in the hull to move the trim cable to the different RXP nozzle mounting location. I didn't want to do this either.
In order to allow the Seadoo pump and Yamaha nozzle to mate up properly I made an adapter that fits between the Yamaha OEM SHO Pump Reduction Nozzle and the Seadoo pump.
For anyone that would prefer to use the Seadoo pump and steering nozzles that can also be done using my adapter. In this instance the trim cable must be moved to match up with the different Seadoo nozzle cable mounting location.
Driveshaft Adapter- In the past others have used an impeller removal tool to make a driveshaft adapter. The problem with this approach is the impeller tool is mild steel so it will wear quickly with use over time. I made my own driveshaft adapter that screws on to the end of the Yamaha OEM driveshaft. My custom hardened stainless steel adapter provides the proper splines to the end of the driveshaft which then mates up to the Seadoo pump. This adapter uses the same material and has the same hardness as the OEM driveshaft.
Impeller Cone - None of the Seadoo impeller nose cones fit the OEM Yamaha driveshaft very well. In the past the quick and dirty approach has been to add some o-rings to a Seadoo impeller cone. The problem is when you do this the cone becomes very difficult to install and remove. Also because of the poor fit the water flow past the cone would not be very good. For these reasons I designed and made a new custom impeller cone that fits the Yamaha OEM driveshaft properly and screws into the impeller as you would expect it should. I used the same principle SpeedFreeks uses on his RXP impeller cones. The cone is designed to shoot the water outwards. This design has been shown to add up to a .5 mph speed gain.
Water Strainer - The OEM Seadoo pump water strainer is very restrictive and it does no allow a barbed fitting to be used to provide a water feed for the motor. My brass replacement strainer increases flow by 33% and allows a fitting to be used to fee water to the motor/IC.
Twin Impellers on a Seadoo Pump!
One of the advantages of using a Seadoo pump is the excellent availability of different impellers and impeller pitches.
My Solas 4 blade RXP impeller gives me very good top end.
For holeshot, running buoys and drag racing I use a Skat 3 blade.
To further improve on a good thing I have upgraded my driveshaft adapter so that it now allows me to use a twin impeller set-up on my Seadoo pump. This allows you to take the Skat inducer impeller that was designed for the Yamaha pump and use it with any of the Seadoo impellers (OEM, Skat or Solas) on the Seadoo pump.
On my ski I am currently using a Solas 4 blade impeller in combination with a 2nd Skat inducer impeller. All I can say is if holeshot is important to you for drag racing this could be the ultimate set-up!
In addition to 2 holes drilled in the pump shoe I am using two one way pressure relief valves installed in the adapter in the 10 and 2 o'clock positions.
SS GP1200R Intake Grate
The rear loading ramp of a SS GPR intake grate was ground down by hand using an air hand grinder with a special bit so that the ramp is the same shape as a R&D GP1200R intake grate. This modification dramatically reduced the cavitation normally associated with a SS intake grate. The first picture of the grates shows the modified SS grate with the rear ramp modified. For comparison purposes a stock SS grate is also shown on the left.
Next I modified the SS grate so that the wing of the SS grate is in the same position as a R&D GP1200R double bar grate. The second grate picture shows the modified SS grate on the right beside a stock R&D GP1200R grate on the left.
This modified grate works extremely well. It acts and behaves exactly as you would expect a 1200 style grate to perform. There is no longer any cavitation or slippage that is normally associated with an 800 style grate.
Air is directed to the motor for cooling from the two openings in the side cowlings. The seat has numerous holes drilled in it to allow hot air to exit from the hull.
Cold air for the supercharger is taken from the front storage bin. To prevent hot air from entering the motor the storage bin is sealed off from the rest of the hull. Extra holes have been drilled in the front hood to allow cold air to easily enter the storage bin area.
An intermediate position was added to the storage bin catch which locks the lid in a partially open position allowing cooler outside air to enter the bin area.
Per Duke's suggestion I have now added a large velocity stack and a protective screen filter on the air intake opening. This should prevent any foreign material to be sucked into the S/C.
Last edited by philip_gpr; 10-24-2011 at 05:39 PM.
08-17-2010, 10:27 AM #2
Last edited by philip_gpr; 03-13-2011 at 10:24 AM.
08-17-2010, 12:29 PM #3
This sounds like it is going to be a really nice build.
I'm envious already.
08-17-2010, 12:37 PM #4
08-17-2010, 01:52 PM #5
08-17-2010, 04:16 PM #6
- Join Date
- Aug 2010
Is this the fastest combo as far as conversion go?
08-17-2010, 05:14 PM #7
Not sure, but it certainly is quicker than the Yamaha 155 pump.
And if I might suggest once you get over 90 mph your priorities might change. I switched to the Seadoo pump to accomplish 2 things:
1) Improve acceleration and get rid of cavitation
2) Replace my Yamaha pump with its broken veins
I spent 10 years with 2 strokes chasing mph. For me anyway that game is over, now everything is about improving acceleration and handling.
08-17-2010, 07:43 PM #8
- Join Date
- Aug 2008
- Southern Florida
Nice Philip...looking forward to watching this thread. When do I get my adapter? lol
08-18-2010, 06:11 AM #9
08-18-2010, 12:02 PM #10
philip you must really love this project, never seen you with a avatar pic
ill be tunned to this build.
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