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  1. #1

    Few Questions- injectors,ecu's

    Ok so i ive still got the stock injectors and im done playing around on the ski till i get something larger. My question is whats the largest injector i can run with the stock ecu and at what point should i really upgrade the ecu to another one? Which brings me to the next question about ECU's what are the different kinds out there? I see one that takes you up to 8800rpm on the limiter and down from there. What is going to get your motor to turn those RPM's im assuming cam and internal work only. Ok so my goal is 85mph whats it going to take to get me there. Also there are a few things already in work which might help this goal happen i got a riva shorty box to install i also am doing the kanaflex like everyone said and the new reduction nozzle is in the works.


  2. #2
    Vern's Avatar
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    $$$

    It will take you $4,000 - 5,000++ in parts to get to 85mph ... not many people have hit 85 mph, and even less without blowing their motor up not long after. 85mph is not cheap or easy and requires far more maintenance, monitoring and tuning.

    ECU $900+ or custom reflash
    BIG SC $1700+
    Big Injectors $300
    Setback pump $1100
    Big impeller $300
    AFR guage $300
    Modded ride plate or open loop $300 - $700+

    Lots of other minor stuff and lots of tuning time on the water. 77 mph on a Stage 2+ is relatively cheap and easy ... add an ECU and some tuning to get 80-81mph, and after that it gets tougher, more expensive and more dangerous (motors go lean, detonate, etc). You gotta decide if you like to ride alot, or tune alot and handle blown motors and down time ... an 85 mph RXP is rarely a 'turn key' reliable ski that you can just jump on and ride whenever you want.

  3. #3
    Dirty Sanchez's Avatar
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    lower your goal to 75-80 which can safely be obtained at less cost
    valve retainers
    re-flash the ecu
    4 in air
    mod ride plate
    prop
    intake grate
    rude charge
    injectors
    xs inner cooler
    misc free mod's
    if you plan on tweeking and tuning AFG & rrfp
    water box & thru hull

  4. #4
    speedskixp's Avatar
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    If you want to go 80+ and be reliable get yourself one of the big daddy chargers and keep the stock ecu. My boat is running 81+ on stock ecu all day long with the mods in my sig. It is alot harder to stay reliable once you go to the high reving ecu's and high boost wich is what it will take to get 85+.

  5. #5

    upgrate

    2005 rxp. STOCK ECU, xs intercooler, ET 68-140 14lbs boost @8100rpm, rrfpr, riva rear intake, wedge, Riva grate 15/20 pitched to 15/24, 81mm ring. 160 degree t-stat mod. 48lb injectors, gh waterbox,4 bars, 81.6 mph all without upgrate your valvetrain?

  6. #6
    Moderator Snoman's Avatar
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    He doesnt need to upgrade his valve train..Hes only spinning 8100 RPM

  7. #7
    Vern's Avatar
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    Plan B

    There is another way, actually a few different ways to get close to 85 mph. You could try another approach and see how far you get ... keep your current engine setup, which with the right nozzle and bend on the 15/20 should easily get you to 77-78 mph.

    Add Jim's open loop plate and open loop/heat exchanger for cooling, approximately $800 and adds 3 - 4 mph per JD1 and others. Then add a setback pump for approximately $1100 for another 1.5 mph. With those two and fine tuning of prop/rpm and bottom you should be running very close to 82 mph with a relatively simple, mild motor setup. Then if you do like Speedskixp recommends and add a Big SC with proper fueling upgrades, you should be very close to 85 mph on stock ECU ... in theory.

  8. #8
    Ok so if i go with a 68-140 charger turn 8100 or so its going to be around 14lbs of boost which wont need valve upgrades but wouldnt this put 48lb injectors close to there limit? If i could get 50lb inj. for cheap could these be ran with the stock ecu?

  9. #9
    speedskixp's Avatar
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    Quote Originally Posted by Edgar800sd View Post
    2005 rxp. STOCK ECU, xs intercooler, ET 68-140 14lbs boost @8100rpm, rrfpr, riva rear intake, wedge, Riva grate 15/20 pitched to 15/24, 81mm ring. 160 degree t-stat mod. 48lb injectors, gh waterbox,4 bars, 81.6 mph all without upgrate your valvetrain?
    No valvetrain upgrade needed with stck ecu.
    Quote Originally Posted by jasonstang88 View Post
    Ok so if i go with a 68-140 charger turn 8100 or so its going to be around 14lbs of boost which wont need valve upgrades but wouldnt this put 48lb injectors close to there limit? If i could get 50lb inj. for cheap could these be ran with the stock ecu?
    You can run 48s or 50s either will work fine with stock ecu and rrfpr. Its not so much that it would be maxing the 48's but more so the fuel pump wich can be upgraded for $90. I have been running my ET with 48s and stock fuel pump without issue. I did however just recently replace my fuel pump just to be safe.

  10. #10
    Ok thats what i wanted to hear i havent seen too much with people putting 50's in there ski's with stock ECU's and 48's are way to expensive i come across alot of 50's for relativly cheap prices. I seen on here where someone took the fuel pump for a mustang or something which is what i have and put it in their ski i think it was a 255lph, im not sure what the stock one is but i think that should handle the demand.

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