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  1. #1

    Mod 07 rxp need ur wisdom for new et68-140 charger

    I have a 07 RXP WITH A ROTAX RACING ECU, 42LBS INJECTOR, STOCK MOTOR WORN RINGS, A 12LB CHARGER, INTERCOOLED. I'M DOING THE TOP END, PUTTING ON THE NEW ET68-140 CHARGER FROM ART AT ENGINE TECH, 60LBS INJECTORS AEM A/F GUAGE AND AEM BOOST GUAGE. HE SAID IT SHOULD DO 85MPH @ 8800RPM WHICH I'D LIKE TO ACHIEVE RELIABLY AND I NEED TO KNOW WHAT PROP, A/F RATIO AND ANYTHING ELSE THAT WOULD MAKE THIS PROJECT RIGHT.I ONLY WANNA DO IT ONCE.HAHA
    THANKS
    4130


  2. #2
    speedskixp's Avatar
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    That will be a good set-up but you are going to need something to control your fueling. Best thing for you would probably be to pick up a cmd with auto tune and a 15/22 prop and pitch from there. Also, if top speed is what you are after you will want to go with a modded rideplate. 85+ is realistic for this if done right.

  3. #3
    Having Fun jp1300r's Avatar
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    Quote Originally Posted by 4130 View Post
    I have a 07 RXP WITH A ROTAX RACING ECU, 42LBS INJECTOR, STOCK MOTOR WORN RINGS, A 12LB CHARGER, INTERCOOLED. I'M DOING THE TOP END, PUTTING ON THE NEW ET68-140 CHARGER FROM ART AT ENGINE TECH, 60LBS INJECTORS AEM A/F GUAGE AND AEM BOOST GUAGE. HE SAID IT SHOULD DO 85MPH @ 8800RPM WHICH I'D LIKE TO ACHIEVE RELIABLY AND I NEED TO KNOW WHAT PROP, A/F RATIO AND ANYTHING ELSE THAT WOULD MAKE THIS PROJECT RIGHT.I ONLY WANNA DO IT ONCE.HAHA
    THANKS
    4130
    Put some good pistons in it with the ROTAX RACING ECU. What the rev limiter on that ECU anyway?

  4. #4
    I'm not sureon the ECU rev limit but Art told me it has a steep advance and will pull 8800. I have a fuel regulator and was suppost to set it in the 55lbs to 58lbs to get 11.8-12:1 A/F but was wondering what is CMD and autotune is? I have powercommander 5 and wideband setup for doin turbo nytro snowmobiles is this similar and what are advantages of it, accel pump features, multi rpm duty rates etc...On our 4 stroke sleds we run extra injectors to add fuel when boost comes on so it runs like a stock machine without the hickups and funny running down low before it boosts.As for the motor i don't have it out yet but it is stock and was told to re-ring but is there better pistons and what what compression? For the 15/22 impeller which kind is the best.Thanks for the help.
    4130

  5. #5
    geowelsh's Avatar
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    Yes, the cmd is similar, it will ad or reduce the injector duty cycle to get you to the air fuel ratio you desire. Not sure exactly what other mods you have but 85 reliably is a big goal. A ride plate yes, is the opas still on the ski, hull truing, engine mods, porting, intake, exhaust, pistons, thermo, ect...

  6. #6
    speedskixp's Avatar
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    Quote Originally Posted by 4130 View Post
    I'm not sureon the ECU rev limit but Art told me it has a steep advance and will pull 8800. I have a fuel regulator and was suppost to set it in the 55lbs to 58lbs to get 11.8-12:1 A/F but was wondering what is CMD and autotune is? I have powercommander 5 and wideband setup for doin turbo nytro snowmobiles is this similar and what are advantages of it, accel pump features, multi rpm duty rates etc...On our 4 stroke sleds we run extra injectors to add fuel when boost comes on so it runs like a stock machine without the hickups and funny running down low before it boosts.As for the motor i don't have it out yet but it is stock and was told to re-ring but is there better pistons and what what compression? For the 15/22 impeller which kind is the best.Thanks for the help.
    4130
    I'm guessing you have an 8800 rotax ecu. One thing about that ecu is that it is mapped to be ran with a rotax cam to get the most out of it and will tend to run a bit rough at idle with stock cam due to being lean. The cmd will help with that. Also, rotax is known for having an aggressive timing curve but not sure that is the case with the 8800 however you must run quality fuel and I would aim for 11.5 a/f at wot to be on the safe side. As for 85mph reliably. Well, that depends alot on how its ridden and how much time is spent at wot. If you plan on beating the crap out of it wot all the time its not going to happen and you will most likely be replacing head gaskets quite often if not worse. Honestly if it were me I would go with a riva ecu for reliability sake although it may cost you 1.5-2 mph and a but of acceleration. As for prop most are running solas 15/22r's.
    Here is a thread on the cmd. http://www.greenhulk.net/forums/showthread.php?t=164229

    I

  7. #7
    So if I go with the CMD what size of injectors do I need and roughly what fuel pressure? Is the stock pistons good enough for this setup or should I change as I have to re-ring anyways?
    4130

  8. #8
    speedskixp's Avatar
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    Quote Originally Posted by 4130 View Post
    So if I go with the CMD what size of injectors do I need and roughly what fuel pressure? Is the stock pistons good enough for this setup or should I change as I have to re-ring anyways?
    4130
    If you plan to re-ring you should upgrade while you have it apart. 60lb injectors will work. I would set fuel pressure around 60lbs

  9. #9
    Quote Originally Posted by speedskixp View Post
    If you plan to re-ring you should upgrade while you have it apart. 60lb injectors will work. I would set fuel pressure around 60lbs
    Upgrade to what, is there better pistons, or better rings for the stock pistons? Were do you recommend I get the injectors from?

  10. #10
    speedskixp's Avatar
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    After determining what size pistons you need, I would go with cp pistons . http://www.4-tecperformance.com/inde...oducts_id=1226
    and these injectors. http://www.4-tecperformance.com/inde...oducts_id=1920

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