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  1. #1

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    69.8 mph stocker with strange results modified (x charger)

    Today, we did a baseline on a bone stock (ceramics and all) '04 RXP, added some mod's, then tested again.

    This morning, for the baseline run, it was 48 deg air and 70 deg water with 4 bars of fuel. Totally stock, I was surprised to see 69.8 mph show up as the max, at 8150 rpm. I actually think it would've broken 70 if we coulda' tweaked the prop a little.

    We then went to the shop and installed a new X-Charger, Riva 4" rear air, RRFPR, and out-the-box Solas 15/20R. Notice, we DID NOT install a Riva Grate, wedge, or any free mod's. The rideplate holes are not filled and the bucket is not trimmed.

    We went back out and ran it again, but it had warmed up to 58 deg air. With 4 bars of fuel, it was on the limiter at 8150 rpm with the 15/20 prop, but only managed to GPS 73.6 mph. It accelerated noticeably better, though, and I was impressed with the X charger for that reason.

    The strange thing is that it was fully capable of spinning the 15/20 prop all the way to the rev limiter, but didn't GPS like you would expect. For instance, a regular Stage 2 will spin the 15/20 to 8100 rpm and go 75-77 mph.

    Any theories as to why it didn't GPS better for the rpm and prop?

    Mike


  2. #2
    ou812's Avatar
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    Quote Originally Posted by engineermike View Post
    Today, we did a baseline on a bone stock (ceramics and all) '04 RXP, added some mod's, then tested again.

    This morning, for the baseline run, it was 48 deg air and 70 deg water with 4 bars of fuel. Totally stock, I was surprised to see 69.8 mph show up as the max, at 8150 rpm. I actually think it would've broken 70 if we coulda' tweaked the prop a little.

    We then went to the shop and installed a new X-Charger, Riva 4" rear air, RRFPR, and out-the-box Solas 15/20R. Notice, we DID NOT install a Riva Grate, wedge, or any free mod's. The rideplate holes are not filled and the bucket is not trimmed.

    We went back out and ran it again, but it had warmed up to 58 deg air. With 4 bars of fuel, it was on the limiter at 8150 rpm with the 15/20 prop, but only managed to GPS 73.6 mph. It accelerated noticeably better, though, and I was impressed with the X charger for that reason.

    The strange thing is that it was fully capable of spinning the 15/20 prop all the way to the rev limiter, but didn't GPS like you would expect. For instance, a regular Stage 2 will spin the 15/20 to 8100 rpm and go 75-77 mph.

    Any theories as to why it didn't GPS better for the rpm and prop?

    Mike
    1.wear ring clearance?

    2.The X charger is more than a usual stage 2 SC setup & you were on the limiter even harder thus losing power. tweak the prop or nozzle down to 8100 & I bet you get 2+

    3.Remember, the stage 2 setup includes the riva gate & adds a solid 100 rpm & 1mph so add that to the equation at getting the rpms down to 8100 & that should be close to 76mph.

  3. #3

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    The wear ring is shot, but it didn't seem to hurt the stock speeds.

    I suppose we'll go ahead and do the low-buck stuff now, including the grate, wedge, fill holes, tweak prop, and a new wear ring. This thing better do 76-77 like that since I've had 2 stage1+ RR wheel combo's go 74-75. The X charger and rear air should be worth 2+ mph over those.

    When I first felt the acceleration of this simple combo, I really expected a lot more top end. The acceleration was much improved.

    Mike

  4. #4
    Having Fun jp1300r's Avatar
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    Stock intercooler? Try and get them to buy a Frizzle IC set up. That and the 15/20 repitched to 15/22-23 and I bet you would see 78-80 mph with the rest of the mods( grate, free mods) done.

  5. #5
    Site Admin Green Hulk's Avatar
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    Mike, put a Riva grate on the ski. I think you will be surprised at how much the speeds come up.

  6. #6
    mtrager's Avatar
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    Mike,

    I have the same set up on my 07. I took a 13/18 and made it a 14/19.
    It burns the prop so bad on the bottom I do not even try. Above 80 degrees
    it was turning 8180 to 8200. Yesterday in was 64 degrees and it was turning
    8300 rpms and not cutting out on top.

    Jp1300 was doing some speed runs yesterday and it ran mid to upper 73's.
    He then put the trim all the way up and it lowered the rpms to 8180 and went 74.3.

    I am going to try a stock x prop in it. If I can make it hook up it is going to have an awesome holeshot. I think my ski will go 75 when it has right prop and 77 with an intercooler.

  7. #7

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    Went and tested again today with these changes:

    -New wear ring
    -Riva wedge
    -Riva grate
    -Trimmed the reverse bucket

    Today, the air was 75 and water 65. 3 bars of fuel.

    Max speed was 75.0 mph, so the changes were worth 1.4 mph or a little more.

    I guess that's about right, though I was hoping for 76. I guess we fill the rideplate holes and hope for 76 in cooler weather.

    It was running right at 8100 rpm, btw.

    Mike

  8. #8
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    You also have to remember that on a stage 2 setup, the IC is different...This gives a denser cooler charge while allowing for WAY better airflow...So with a restrictive OEM IC, and its not so efficient cooling, you are getting great numbers...

    AND its technically still a Stage 1

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