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  1. #1
    home of the dislexic fingers breon's Avatar
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    just some good info from our friends in aussie land

    The very first thing you should do to your supercharged watercraft is switch the stock ceramic supercharger clutch washers for the special metal washers that are now on the market. A failure of a ceramic clutch washer can cause many problems and will destroy your oil pumps.
    Here is where to find the Washers:
    Les Cooke Australia
    Piranha-parts Australia
    Green Hulk USA


    A few of the very first things most people do to their skis is install a grate, remove the OPAS system (training wheels) and install a Riva finger throttle/wider handlebar kit.

    As far as grates go the Riva grate has been proven time and time again to out perform all others and even increases speeds on the higher modified crafts. When removing OPAS you have several options. On the GTX or RXT platforms the OPAS paddles move up and down. Many times a filter in the system can become clogged causing the OPAS paddles to remain in the lower position below the waterline resulting in poor performance. You have the option of purchasing a Riva Competition OPAS kit which basically snaps in place to hold the OPAS paddles in their upright position at all times, or just remove them completely. Riva makes a block off kit for all of the Sea Doo 4-Tec's that completely removes the OPAS system. This is the route most choose to go. For the RXP, Riva makes a Pro Series block off kit that actually extends the OPAS opening further rearward which improves handling tremendously over the standard block off plates. These Pro Series block offs are IJSBA legal for racing. For those that aren't concerned with being race legal you have the option of going with the Race Engineering OPAS block off kit which extends the hull to cover the entire OPAS opening. Handling with these block off's is superior to all others. They improve hookup in chop, cornering and the overall feel of the ski is amazing.


    First i will discuss staged kits and then i will talk about mixing and matching components.

    Many people choose to jump straight to a Stage 1 kit which includes all the basics. Riva offers a Stage 1 kit that includes the grate, a 14/19 Solas impeller, 3" air intake kit, and a 2 degree pump wedge.
    The 14/19 impeller will deliver better acceleration and top speed. The air intake will help the engine make more power which is necessary to turn the high pitch impeller at top RPM's. The wedge helps raise the bow of the ski up which increases top speed. Less wetted hull surface results in less drag. Some people don't like the way the wedge makes their ski handle while others love it. For RXP owners, they may opt to go with the VTS extension rod which greatly improves hole shot when running a wedge.

    If it's more power you seek then it's available in many forms. Basically, the addition of an external intercooler, Riva/Vortech/ Les Cooke supercharger impeller, thru hull exhaust and Solas 15/20 impeller will bring you to Stage 2 status. Riva's stage 2 kit offers all of the components of the Stage 1 kit plus the parts i just mentioned above and also includes Riva sponsons. Sponsons work to improve the handling of your ski and improve straigtline tracking thru chop. Handling is a very subjective thing though. What handles good to you may not handle good to someone else. In fact, some closed course racers choose to stick with the stock sponsons and retain the OPAS system.

    Piranha-Parts offer a great option for all stage 2 Lookers
    http:// www.piranha-parts.com/pp_powerkit.pdf

    The 15/20 impeller is necessary at the Stage 2 level of modifications because you are obviously making more power now and with a smaller impeller you would find that your engine ran against the rev limiter. For optimum performance you want your pitch to hold your RPM's just under the rev limiter so you effectively use up all of the engines usefull powerband.

    The intercooler in the Stage 2 kit is an external intercooler and makes a ton more power than that of the stock intercooler which is mounted in the intake manifold. The stock intercooler is removed and then blocked off with a billet block off plug that is provided in the kit. It's also worth mentioning that the stock intercooler is extremely restrictive. My testing has shown a 1 psi increase in boost when going from the stock intercooler to the external intercooler.

    To make room for an external intercooler a thru hull exhaust must be used. The thru hull exhaust not only gives better performance by being less restrictive it sounds amazing.

    There are actually a couple of Manufactures that make Intercoolers and Rear Exhausts. You will find it hard to beat the price and Performance that is offered by PIRANHA-PARTS
    Piranha-parts
    Riva Motorsports
    Mark Underwood
    Green Hulk


    For those not wanting to go with a thru hull exhaust, but still want to run an external intercooler an option would be to go with the Rotax Racing intercooler with their intercooler plumbing/mount bracket kit.



    I have been asked many times, "why not leave the stock intercooler in place while running the external intercooler? Two has got to be better than one right?" The answer is no! Intercoolers are restrictive devices. If you throw both of them into the mix performance is deteriorated.

    The Riva/Vortech/Les Cooke supercharger impeller provides more boost than the stock supercharger impeller, but more importantly it delivers a greater volume of air. This impeller noticeably increases acceleration. In fact, many people with a basic Stage 1 kit have used this impeller and were very excited with the improvement it gave them.

    If you find you want more performance than what a Stage 2 can deliver there is always more available To bring your ski up to a level of Stage 3 you can add an aftermarket ECU. Riva offers a Stage 3 kit which consists of all the components in their Stage 2 kit plus an ECU, 50# injectors, higher boost supercharger with modified front housing, higher rate valve springs with lightweight titanium retainers, 158 degree thermostat, 15/19 3 blade Skat impeller and a adjustable venturi nozzle.

    There are a couple of aftermarket ECU's available to us. The Riva ECU and the Rotax Racing ECU. The important thing to remember is the Riva ECU is mapped to work with 50# injectors. (stock injectors are 38#) The Rotax Racing ECU can be run with the stock injectors, or larger 42# injectors if running a higher boost supercharger. (more on this later)
    Both the Riva and Rotax Racing ECU's have a higher rev limit of 8600 RPM's. With either ECU you must upgrade your valvetrain to handle the higher RPM's to prevent valve float. The valvetrain upgrade Riva offers in their Stage 3 kit consists of higher rate springs, a shim that goes under the spring and also lightweight titanium valve spring retainers. This valvetrain kit is effective and easy to install without removing the head using Riva's valvetrain tool. Rotax Racing offers lightweight aluminum valve spring retainers and spring shims, but it is advised that if you plan on running 8500+ RPM's with the Rotax Racing retainers/shims that you also have the valves lightened. This requires head removal.

    There are also a couple of 158 degree thermostats on the market. Rotax Racing offers a complete thermostat that just bolts in place. Riva offers a kit that you use to modify your stock thermostat to convert it over to 158 degrees. The stock thermostat is a 188 degree unit. Your engine running 30 degrees cooler with the aftermarket thermostats also keeps the oil temperature down which prevents oil viscosity breakdown and also extends your oil life.

    The adjustable venturi nozzle offered in Rivas Stage 3 kit is actually something can be run on any ski with any level of modifications. This is a handy tool to have so that you can easily dial in your RPM's for maximum performance without having to repitch the impeller. It comes with 3 ring sizes. The larger the ring the higher the RPM's. The smaller the ring the less RPM's you will turn. Also, most people find that the 81mm ring gives them the highest top speed. The stock venturi is 83mm.


  2. #2
    home of the dislexic fingers breon's Avatar
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    Part 2

    The supercharger impeller that comes with the Riva Stage 3 kit also comes with a modified front housing that accomodates the taller blades on the impeller. This supercharger produces a great deal of boost and also moves a very high volume of air resulting in greatly improved performance.
    This supercharger isn't limited to just skis with a Stage 3 level of modifications though. I have seen people with as little as a Stage 1 kit run it with great success. If you aren't running the Riva ECU and you want to run this supercharger you must use 42# injectors with either the stock or Rotax Racing ECU's.

    There are quite a few options when it comes to superchargers. I will list below the different superchargers on the market and which injectors will be necessary to run them. The list will go from the weakest supercharger to the strongest.

    Stock SC - stock injectors

    Riva/Vortech SC - stock injectors

    Rotax Racing High Boost - stock injectors with stock intercooler. 42# injectors with external intercooler

    Les Cooke A-Kit Impeller 10lbs Boost with Complete Stock Ski is fine

    Riva Stage 3 SC - With Riva ECU you will need the 50# injectors. With stock ECU or Rotax Racing ECU you will need 42# injectors

    Rude Performance "Rude Charger"or Les Cooke "B" kit SC - You will need a piggy back fuel controller to run this supercharger with either the stock ECU or Rotax Racing ECU. You will also need to run 50# injectors. Another alternative is to run the Riva ECU with 50# injectors as this ECU is boost dependant and can handle the increased fuel requirements as boost rises.
    The B-Kit SC can also run the stock ECU & Stock Injectors but must use the stock OEM Air intake.
    Back to back testing was done with both the Rotax Racing with fuel controller and Riva ECU's with the B kit supercharger and found that the Rotax Racing combo gives the best performance. I think this is due primarily because with the Riva ECU as boost rises it also backs out timing. The Rotax Racing combo has a noticeable improvment in power over 8400 RPM's than that of the Riva.
    Its also worth mentioning that the way the Riva ECU is mapped is probably much safer when running this combo, although i have never had any problems with running the Rotax Racing ECU with the B kit.

    When running these higher boost superchargers its important to feed the supercharger as much air as possible. Those that have an RXP are lucky in that Riva now has a 4" rear air intake kit that works extremely well. Many of us, including myself have fabricated our own custom 4" intakes using a 4" adaptor coupler that attaches to the SC opening and utilizes a 4" flexible hose that runs to the front of the ski. While this setup is good, it can be improved by making a 4" rear air intake. I have found 1 psi more boost from switching from the 4" front intake to a 4" rear air intake.
    The Rear Intake not recommended for Ocean riding or Wave jumping.

  3. #3
    Site Admin Green Hulk's Avatar
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    Breon, where did you get that? That is a copy of my article found here

    http://greenhulk.net/forums/showthread.php?t=16773



  4. #4
    DaveC's Avatar
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    Jerry it is over here http://www.4-tecforum.com/forumdisplay.php?f=1 under performance section. It is almost word for word in alot of areas, hell I was thinking you had some kind of deal with them.

  5. #5
    Site Admin Green Hulk's Avatar
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    Yea, i remember now them asking my permission to post that. It's all good

  6. #6
    home of the dislexic fingers breon's Avatar
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    they plug you too ...you should post it up top with the specials and stuff it has alot of good info probably curb some of the simple simple questions .....that forum only has 3 people on it i swear... i found it first and posted questons that remained on the first page unanswered for weeks..this forum is the best i have found

  7. #7
    EZ Dock of Long Island Shibby1485's Avatar
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    Quote Originally Posted by breon View Post
    ..this forum is the best i have found
    look no further!! this is THE place to be

  8. #8
    home of the dislexic fingers breon's Avatar
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    i agree shib

  9. #9
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by breon View Post
    this forum is the best i have found
    I agree, this is truely an amazing place. It's not all my doing though. It's you members that make this place so great

  10. #10
    FIRED!!! JP's Avatar
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    Quote Originally Posted by Green Hulk View Post
    I agree, this is truely an amazing place. It's not all my doing though. It's you members that make this place so great
    I luv ya man!!!

    JP

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