Results 1 to 10 of 10

Thread: LSJ Challenge: Mean Mini

  1. #1
    Tuner in Training TheBritishColumbian's Avatar
    Join Date
    Jun 2014
    Location
    Smithers, BC
    Posts
    23

    LSJ Challenge: Mean Mini

    Alright guys I have an odd ball project, and I mean out there. I have an LSJ in a mini jetboat running the P12. I'll start by explaining some of the differences in installing an engine in a jetboat.
    1. The motor is directly coupled to the jet so it is always underload and the rotating mass is very high. Think massive flywheel with the clutch always dragging.
    2. The intercool is fed river water, IAT2 is almost always below 30C, unless the boat has been sitting. Generally the faster I go, the higher the boost, the more water it sees.
    3. There is no wind cooling the oil pan. All cooling come from a heat exchanger. I have a large one.
    4. Pedal throttle in the small boats; this is idea but the driver does get tossed around so it is tough to keep even pressure.
    5. The jet abosorbs a certain amount of HP at a certain hp. This is independant of speed. It's a constant thrust per rpm.
    6. The exhaust is water jacketed and water injected. No 02's. I can run the factory header with the hood off, but without wind it starts to glow very quickly. This is a large fire hazard for long term use.


    I am having two issues right now:
    1. Idle fluctuates once the engine is up to temp. I turned the idle up (1000rpm warm) to try and help the motor deal with the load but I still get a ~600-1300rpm fluctuation.
    2. I am getting spikes in my injector duty cycle at WOT even though my pedal and commanded AFR are constant.

    In the log it is idling until frame 115 then I tour around from there.
    Stg 2 Ingition.hpt (Current Tune with Slightly hotter ignition which is actually worth about ~15hp (200rpm)
    day 2 t1.hpl (Log file after a tour around the river)

    Pump Power Absorption Curve (772 Standard 106 Curve)
    Pump Curve.PNG

  2. #2
    Tuner in Training TheBritishColumbian's Avatar
    Join Date
    Jun 2014
    Location
    Smithers, BC
    Posts
    23
    In case anyone else is bombing around with this issue it was the DFCO kicking in when the ETC tried to bring the idle down.

  3. #3
    Senior Tuner
    Join Date
    Apr 2007
    Posts
    1,104
    what mods to the engine itself?
    The most hated, make the most power.
    93 Ranger. 5.3 D1X. 1069hp.

  4. #4
    Tuner in Training TheBritishColumbian's Avatar
    Join Date
    Jun 2014
    Location
    Smithers, BC
    Posts
    23
    Marine Exhaust Manifold with 3.5" piping going through inline muffler
    3" Intake and MAF relocation
    4" heat exchanger

  5. #5
    Senior Tuner
    Join Date
    Apr 2007
    Posts
    1,104
    maf relocated where? Stock drive by wire system i am guessing?
    The most hated, make the most power.
    93 Ranger. 5.3 D1X. 1069hp.

  6. #6
    Tuner in Training TheBritishColumbian's Avatar
    Join Date
    Jun 2014
    Location
    Smithers, BC
    Posts
    23
    Quote Originally Posted by Area47 View Post
    maf relocated where? Stock drive by wire system i am guessing?
    THE BIN! Just kidding, it's in a nice tube that isn't the original filter housing between the filter and etb. Drive by wire yes, the footpedal is the best option in small boats.

  7. #7
    Advanced Tuner laser_racer's Avatar
    Join Date
    Jul 2009
    Location
    league city tx
    Posts
    461
    Do you have a wideband on this?

  8. #8
    Tuner in Training TheBritishColumbian's Avatar
    Join Date
    Jun 2014
    Location
    Smithers, BC
    Posts
    23
    I have to swap the stock manifold back on. I'm working on an intermediate tube before the water injection to be able to run it temporarily with the wideband in my marine manifold.

  9. #9
    Advanced Tuner laser_racer's Avatar
    Join Date
    Jul 2009
    Location
    league city tx
    Posts
    461
    Makes me wonder if its running to lean and timing is to low. Thats what we usually see causing the manifolds to heat like that.

  10. #10
    Tuner in Training TheBritishColumbian's Avatar
    Join Date
    Jun 2014
    Location
    Smithers, BC
    Posts
    23
    Which manifold heating like what?