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  1. #1

    Join Date
    May 2008
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    fuel inj. for 50lb reflash

    well it goes like this... RXT with x pro sc/xs ic/ 4 inch air

    50's base is set at 38 psi to get 11.7 12.0 a/f ratio @wot but is rich @6600 cruis speed @ 10.0 and boggs out of the hole.

    48's base is set at 44 psi to get same a/f as above @wot and still rich @ cruise 6600 10.0 a/f. and boggs out of the hole

    42's base is set at 68 psi to get the same a/f as above @wot and i have an a/f of 10.6/9 at cruise 6600. and does not bogg out of the hole.

    so my question is...is it okay to run the ski with such a high base pressure with the 42's. these runs are all on the stock fuel pump. i am thinking POWERCHIPS may have messed up the ecu program on the bottom end. any thoughts thanks.


  2. #2
    Richieb's Avatar
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    Oct 2008
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    Sydney, Australia.
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    Simple. Never run ANY injector at less than 43.5psi.

    The spray pattern is designed to run a minimum of this, less psi will give a splattery, inefficient, under-fuelled injection of fuel.

    Under 43.5 psi will give the same symptoms of a bad pump, or delivery.

    After about 68-70 psi, the pintle valve in the injector cant hold back the fuel, and starts to leak, and cannot measure the correct dose of fueling.

    There's the band you can work within. Either increase/decrease the injector capacity, or reduce/increase fuelling pulse from ECU.

    NEVER UNDER PRESSURE the injectors. Preferably keep a good, safe margin of drop/error too. 43.5psi is MIN pressure, Then a good RRFPR to compliment charge pressure ratio at injector nozzle to maintain min pressure at exit.

  3. #3

    Join Date
    May 2008
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    metairie,la
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    so should i stick with the 42's?? @ 68psi i was hitting 8530 rpm with the 42's . and with the 48's and 50's i see 8400. i cant send it back to pwerchips so i dont know wtf to do here

  4. #4

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    May 2008
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    metairie,la
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    just dont want to burn up the fuel pump

  5. #5
    HORSEPOWER JUNKIE 9secZO6's Avatar
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    Jun 2007
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    Belle Chasse, La.
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    We did not ride long enough together yesterday, but I have a "base" on the water u can tune from. My dock w/ 2 slips and ski lift are what u need to test, change parts, test, etc. all w/o leaving the water, 3min from where u launched. This can be done w/ those 42's on a stock ecu, but now it's mapped for 50s.....

    We ride almost 7 days a week from about 5pm until we are dodging bugs coming in at dark. Any day but wed. is good, u won't get a more clear invitation than that Remember what I said about being too rich, it is NOT condusive to long piston ring life.

  6. #6

    Join Date
    May 2008
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    metairie,la
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    Quote Originally Posted by 9secZO6 View Post
    We did not ride long enough together yesterday, but I have a "base" on the water u can tune from. My dock w/ 2 slips and ski lift are what u need to test, change parts, test, etc. all w/o leaving the water, 3min from where u launched. This can be done w/ those 42's on a stock ecu, but now it's mapped for 50s.....

    We ride almost 7 days a week from about 5pm until we are dodging bugs coming in at dark. Any day but wed. is good, u won't get a more clear invitation than that Remember what I said about being too rich, it is NOT condusive to long piston ring life.
    you have convinced me. i will do it next time out. maybe next sunday you can help me out. i will come by early with these 3 set of fuel injectors and figure this out. thanks J

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