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Thread: 100 Mph Rxp

  1. #1
    Vern's Avatar
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    100 Mph Rxp

    100 mph RXP??? Some people are very close or have possibly already hit the number, like Dan (JD1). It made me think a bit about what parts it takes to get there, so I thought I would throw out the following to think about and speculate about (disclaimer - I only know what I have read on the boards about the really fast skis). Some of these ideas might also help skis with less than 300 hp go faster than they are today too, which is my main interest. I am interested in any input from people with experience or knowledge of any of the 'additions' listed below ... especially the experts who might already know all the answers ...

    Setups we know:
    22+ lbs boost (turbo) at 9000+ rpm (Motec/Autronics/??? ECU) = 90++ mph (Malvin, Stickem)
    18 lbs boost (turbo) at 8500 rpm (Riva/RR ECU) = 86 mph (Jerry)

    Possible additions to Jerry’s turbo RXP:
    Setback pump = 2 mph
    Custom rideplate = 1 - 2 mph
    Bored pump liner, larger custom impeller = 1+ mph?
    OR Custom large pitch Solas 4 blade impeller = 1+ mph?
    Bigger throttle body = 1 mph?
    Better exhaust manifold/header = 2 – 3+ mph?
    Other pump mods = 1 mph+?
    Better camshaft = 1 mph
    In theory adding all the above to Jerry's turbo ski might get it well into the 90's ... but I don't know, its just theory and I know there are likely other important speed things that are not listed.

    Restrictions – comparing our modded (Stg3+ big boost) 4-tec engines that are 275 – 350++ hp, to similar hp V8s, IMO we have some engine bottlenecks. Our single 2 inch exhaust tubing and stock log manifold - a 300 hp V8 typically has headers and dual 2.5 inch exhaust, more than double the potential exhaust flow we have on our skis. The throttle body, RXP stock is 58mm, 5.0L 302 at 300 hp, 70 – 75mm (aftermarket). Just some thoughts ...
    Last edited by Vern; 12-28-2007 at 01:23 PM. Reason: fix


  2. #2

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    I am as passionate about speed as you are but anything over 90 on these things would be my limit. To each his own and please don't fall off.

  3. #3
    DaveC's Avatar
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    I believe it was JD 1 posting about the pump setback mod earlier in the year, is that mod/parts availble yet ?

  4. #4

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    Quote Originally Posted by Vern View Post
    ... The throttle body, RXP stock is 58mm, 5.0L 302 at 300 hp, 70 – 75mm (aftermarket). ...
    Keep in mind that compressed air is far more dense than atmospheric air. Just for comparison, my turbo Z28 has twin 58 mm throttle bores and it's no restriction at 1000 hp. So, a single 58 would be no restriction at 500 hp.

    Mike

  5. #5
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by smc View Post
    I am as passionate about speed as you are but anything over 90 on these things would be my limit. To each his own and please don't fall off.
    I was on the interstate last night and brought my vechicle up to 92 mph. I had a look at the road whizzing by me, looked over at the trees and they were a blur and realized i had gone this fast on a jet ski. It's really nuts when you think about it. I pray to God nobody gets tossed at those speeds or higher. It won't be pretty!

  6. #6
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by engineermike View Post
    So, a single 58 would be no restriction at 500 hp.

    Mike
    I agree! I think we will find little as far as gains go in the throttle body and the exhaust. Forced induction is working to our advantage here.

    The big numbers will be from the proper setup of the ski.

    Ride plate angles
    set back pumps
    grates and grate angle
    chine size and shape
    Impeller pitch and nozzle combinations

    All of these areas will give us huge speed with less horsepower. We just need to find the right combination.

  7. #7
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    Quote Originally Posted by Green Hulk View Post
    All of these areas will give us huge speed with less horsepower. We just need to find the right combination.


    I concur...

  8. #8
    TERRY bigbuck12345's Avatar
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    The big numbers will be from the proper setup of the ski.

    Ride plate angles
    set back pumps
    grates and grate angle
    chine size and shape
    Impeller pitch and nozzle combinations

    All of these areas will give us huge speed with less horsepower. We just need to find the right combination.

    COME ON!!! NOW WERE TALKING

  9. #9
    Nonstop, all day, everyday. 01xdime's Avatar
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    Think about the power these setups are making compared to the fast 2 strokes. Now think about how fast they're going with the difference in power. Hull design set aside there is a lot to be found in the pump/rideplate area. It's just expensive and time consuming to do the R&D for your average joe to takcle. Also another reason why most of that stuff is kept secret.

  10. #10
    subarupartsdude's Avatar
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    Yes............the secrets are in the hull!!!!!!!!!
    If you don't think so..........ask tommy jordon with fountain.
    If i remember correctly,they have a 1300cc easily going 80++++

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