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  1. #1
    RXP-SA Ivaan's Avatar
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    Bloemfontein, Free State, South Africa
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    Some question, maybe some answers.

    After more that a year of playing with my RXP I need the some assistance. I know the help is right here on GH.

    This weekend went out and tested my final upgradings. I have to say I'm at altitude of around 4500 ft. With my A/F ratio's around 12.5 to 13.5 with my RRFPR. I also have a 15-20 solas and other upgrades as in my signature. My concerns are that I only saw 980 mbar (14.2psi) boost levels at my maximum rpm of only 7950 to 8050 this with a ET 70-145!

    I have a pump wedge, should I remove it? I also have a 81mm nozzle ring what should the size be for my impeller size? What is the absolute maximum rpm I can use my stock motor internals without blowing it up? I will upgrade the internals (valves, oil nozzle, flywheel bolts ect) as I reach the stock motor limits. Should I open the pump nozzle or bend the impeller to up the rpm or both? I did not use GPS to measure speed this weekend, my bad, but I need to get the rpm up before trying to get speed numbers better.

    My thoughts are to open the nozzle to 84mm and keep the impeller, get the rpm to 8400rpm and this will get the boost up to 16psi??? I also saw a p0545 code, exhaust temp sensor grounded, visually inspected wiring and all seems fine. Where should I start to rectify?

    Please comment....


  2. #2
    2006 Turbo RXP boBO's Avatar
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    First check a/r ratio, second what injectors are you using, what is the slip set on the charger
    I would keep the 15/20 and 81 ring nozzle

  3. #3
    RXP-SA Ivaan's Avatar
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    Injectors are GH 48# and my A/F was 12.5 to 13.5. Rather let me ask, what should it be, fos forced induction isn't this ok, or should it be more rich? The slip hasn't been tested again what is correct settings for a ET 70-145. Bought it from this forum second hand.

  4. #4
    there's a high altitude rider...named....skeopp.

    hit him up.

  5. #5
    2006 Turbo RXP boBO's Avatar
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    A/F MUST be between 11,8~12,2
    set the slip on the charger @ 19ft-lb

  6. #6
    West Texas RXP skoepp's Avatar
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    Quote Originally Posted by Ivaan View Post
    After more that a year of playing with my RXP I need the some assistance. I know the help is right here on GH.

    This weekend went out and tested my final upgradings. I have to say I'm at altitude of around 4500 ft. With my A/F ratio's around 12.5 to 13.5 with my RRFPR. I also have a 15-20 solas and other upgrades as in my signature. My concerns are that I only saw 980 mbar (14.2psi) boost levels at my maximum rpm of only 7950 to 8050 this with a ET 70-145!

    I have a pump wedge, should I remove it? I also have a 81mm nozzle ring what should the size be for my impeller size? What is the absolute maximum rpm I can use my stock motor internals without blowing it up? I will upgrade the internals (valves, oil nozzle, flywheel bolts ect) as I reach the stock motor limits. Should I open the pump nozzle or bend the impeller to up the rpm or both? I did not use GPS to measure speed this weekend, my bad, but I need to get the rpm up before trying to get speed numbers better.

    My thoughts are to open the nozzle to 84mm and keep the impeller, get the rpm to 8400rpm and this will get the boost up to 16psi??? I also saw a p0545 code, exhaust temp sensor grounded, visually inspected wiring and all seems fine. Where should I start to rectify?

    Please comment....
    I got your pm and now replying for you.

    Welcome to the world or RAD. At your elevation 4,300 ft. your rad will be below 4,000 ft in the winter and could be up as high as 8,000 ft RAD in the summer with heat. For every 1,000 ft of RAD you can figure about 100 to 120 rpm loss. Those are my findings.
    If your seeing 14+ psi boost at 8,000 rpm then I would have to say your charger is setup correct.

    As far as your AFR, what rpm are you seeing 12.5 to 13.5???
    If that is at wot your are way lean and need more fuel, which should be easily corrected by adding fuel to your RRFPR.
    Usually adding fuel is a none issue at elevation, its usually the removing fuel and still have a good tune that is more difficult.
    So give back some more info on AFR at idle, mid, and WOT.
    Running at altitude or high RAD takes a totally different tune then these guys at sea level.

    What i have noticed the most, at 5,000 ft + RAD it is very hard to get the last rpms out of the ski.
    What i mean by that, is, it takes alot more pitch out of prop to go a certain amount of rpm. For instance a -1 mm bend out of prop might bring up rpms at sea level aprox 100 rpm. At 5,000 ft rad it takes more pitch removed to gain that rpm back. It is almost like hitting a wall. The ski may run awesome up to a certain rpm and then take tons of tunning just to gain the last 100 to 200 rpm.
    I never have been able to get a 81 ring to work for me at 5,000 ft RAD. I have the best luck with 83 ring.

    As far as the internals, it may be a blessing you are only turning 8,000 rpm. I would not push it much further without some head work (valves, springs,) and fly wheel bolts replaced oil reg replaced in head, or you might have to replace more then that pretty soon.
    I am sure ski has 100 + hours being 04 so sooner the better on the internal upgrade before you turn the RPM up IMO.


    Good Luck!!!!

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