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  1. #1

    High Compression with RR 8800 ECU and RR supercharged impeller..

    Hi,
    I read somewhere on the site that Using the RR 8800 ECU with hign compression pistons would give me great acceleration..

    My question is,if i run this two items and run a RR supercharged boost impeller... would this be reliable to run with 97 octane fuel?


  2. #2
    sp_RXP_GR's Avatar
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    I was running high compression with 8800 rr ecu & b-kit
    with zero issues...

  3. #3
    R88ory RXP's Avatar
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    Quote Originally Posted by Black_982008 View Post
    Hi,
    I read somewhere on the site that Using the RR 8800 ECU with hign compression pistons would give me great acceleration..

    My question is,if i run this two items and run a RR supercharged boost impeller... would this be reliable to run with 97 octane fuel?
    Pretty sure the RR ecu is mapped for high comp engine nyhow, should be just fine. I would still monitor your Af ratios tho to make sure yoyr gettung enough fuel ontop. R88

  4. #4
    Quote Originally Posted by sp_RXP_GR View Post
    I was running high compression with 8800 rr ecu & b-kit
    with zero issues...

    Thank you for your reply.. What octane fuel were you running??
    Did the ecu performance better with the high compression pistons?
    And what speeds did you get sir?

  5. #5
    Quote Originally Posted by R88ory RXP View Post
    Pretty sure the RR ecu is mapped for high comp engine nyhow, should be just fine. I would still monitor your Af ratios tho to make sure yoyr gettung enough fuel ontop. R88
    Thanks for the info.. Running the RR 8800 ecu,b-kit rr cam and RR high boost supercharged impeller.. whats speeds should i be seeing? and is this the best set up for cc racing?

  6. #6
    R88ory RXP's Avatar
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    Quote Originally Posted by Black_982008 View Post
    Thanks for the info.. Running the RR 8800 ecu,b-kit rr cam and RR high boost supercharged impeller.. whats speeds should i be seeing? and is this the best set up for cc racing?
    Setup for CC you will see high 70s I would suspect, allot of the guys on here tune only for topspeed, obviosly you are racing so its a whole different way of thinking.

    That will be a very strong setup for CC, get the engine reving to 8700 you dont want to be right on the limiter for racing, I would run a 3 blade skat, im running 14/18 in my GP ski. Although with some work a 4 blade can pull real good out of the hole and will win in the mid range and top end.

    R88

  7. #7
    Quote Originally Posted by R88ory RXP View Post
    Setup for CC you will see high 70s I would suspect, allot of the guys on here tune only for topspeed, obviosly you are racing so its a whole different way of thinking.

    That will be a very strong setup for CC, get the engine reving to 8700 you dont want to be right on the limiter for racing, I would run a 3 blade skat, im running 14/18 in my GP ski. Although with some work a 4 blade can pull real good out of the hole and will win in the mid range and top end.

    R88
    ok,so for a RXPX what prop would you suggest to start with for top speed? for good holeshot?

  8. #8
    ROTAX RACING performance
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    you need minimum 98 octan RON fuel (93 octan US fuel), if you dont have good fuel you should not use high compression, you can get 80 mpH on flatwater with that setup , if you run a 83 mm nozzle and 8680/8740 prop speed
    you will also have to use a RIVA or RS Intake grate

  9. #9
    R88ory RXP's Avatar
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    Quote Originally Posted by Black_982008 View Post
    ok,so for a RXPX what prop would you suggest to start with for top speed? for good holeshot?
    For topspeed do as mrracing says run a riva or RS modle intake grate and get a solas 15/20 and pitch it to turn 8700, in flat water you should be able to get 80 like that, For better holeshot I would run a 3 blade 13 or 14/18 and pitch it for the same rpms, it will jump real hard then.

    You can also play with the nozzle size, top speed will be better with a smaller nozzle but I wouldnt go any smaller then 83 on the RXP-X hull 85mm will give very good holeshot and still good topspeed numbers.

    Its all very ski/engine dependant and what you want, size of course your racing on, there is zero point having a ski that can do 85 but take a little time getting there when you can have a 78-80mph setup that gets there real fast when racing a small course and vice versa on a bigger course as the high topspeed boats would come past if the the hole shot was longer and faster.

    As Malte has said also make sure your running high grade fuel!!! esspecially with the high comp. What compression are you running???

    Take care R88

  10. #10
    Quote Originally Posted by R88ory RXP View Post
    For topspeed do as mrracing says run a riva or RS modle intake grate and get a solas 15/20 and pitch it to turn 8700, in flat water you should be able to get 80 like that, For better holeshot I would run a 3 blade 13 or 14/18 and pitch it for the same rpms, it will jump real hard then.

    You can also play with the nozzle size, top speed will be better with a smaller nozzle but I wouldnt go any smaller then 83 on the RXP-X hull 85mm will give very good holeshot and still good topspeed numbers.

    Its all very ski/engine dependant and what you want, size of course your racing on, there is zero point having a ski that can do 85 but take a little time getting there when you can have a 78-80mph setup that gets there real fast when racing a small course and vice versa on a bigger course as the high topspeed boats would come past if the the hole shot was longer and faster.

    As Malte has said also make sure your running high grade fuel!!! esspecially with the high comp. What compression are you running???

    Take care R88
    Not sure but i plan to run those riva 9.5 to 1 compresssion pistons.. would 97 octane do?

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