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  1. #11
    Best of both worlds! RXP & RXT's Avatar
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    That is so cool!! That means that I was making 285hp when I was testing my turbo rxt (see my turbo rxt thread)


  2. #12
    Gone in 3.0 seconds... RXPT400's Avatar
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    Great post....

  3. #13
    I'm kind of a big deal SeanCucf's Avatar
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    Wow.......just wow.

  4. #14

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    I, for one, can vouch for the fact that the stock ecu will command a 100% duty cycle. Most stock ecu's won't for fear of overheating the injector coil. Anyway, I've found that it's a funciton of boost, not rpm. I was able to get 100% DC at 7700 rpm or less at higher boost levels.

    Mike

  5. #15
    BIG BOOST stickem's Avatar
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    Heres some quick conversions also

    • Conversions
    • 500cc per minute is approximately equal to 49lbs per hour which is equal to approximately 100hp.
    • lbs/hour = cc per minute / 10.5
    • lbs per hour = HP / 2.04
    • cc per minute = lbs per hour x 10.5
    • cc per minute = HP x 5
    • HP = cc per minute / 5
    • HP = lbs per hour x 2.04

  6. #16
    Dave Sharp dav_dman's Avatar
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    Quote Originally Posted by engineermike View Post
    I, for one, can vouch for the fact that the stock ecu will command a 100% duty cycle. Most stock ecu's won't for fear of overheating the injector coil. Anyway, I've found that it's a funciton of boost, not rpm. I was able to get 100% DC at 7700 rpm or less at higher boost levels.

    Mike
    I like your AEM F/IC setup, mike.
    I dont like the 100% duty cycle.

  7. #17

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    Quote Originally Posted by dav_dman View Post
    I like your AEM F/IC setup, mike.
    I dont like the 100% duty cycle.
    The stock ECM does 100% duty cycle. The AEM will also command 100% duty cycle. It just has a problem understanding the stock ECU's command to go 100% since it has to measure a pulsewidth. All I had to do is clamp the stock map sensor voltage so the stock ECU never sees max load and goes static. Luckily, the AEM has a feature to clamp voltage on factory sensors.

  8. #18
    Happily Self-Employed WFO's Avatar
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    Quote Originally Posted by engineermike View Post
    I, for one, can vouch for the fact that the stock ecu will command a 100% duty cycle. Most stock ecu's won't for fear of overheating the injector coil. Anyway, I've found that it's a funciton of boost, not rpm. I was able to get 100% DC at 7700 rpm or less at higher boost levels.

    Mike
    Not questioning the capability of the ECU, just the integrity of the injectors running at 95-100%. I am pretty new new to 4stroke PWCs, not 4 strokes. I figured you would over-exercise the injector and that rate, unless they are something special. In the automotive industry, Honda is the only one I am aware of that runs 95% DC, the rest stay at 80-85%.

  9. #19
    I have an interesting question, but first let me preface the question with some supercharger-related characteristics. When air is pressurized (supercharged) by the supercharger the result is an increase in air density. Due to the compression process the heat of compression is added to the supercharged air warming the air and reducing the air density. When the air passes through the intercooler, and is cooled, this results in an increase in the air density. After the intake charge finally makes it to the intake tract, by the valves in the head, fuel is added by the fuel injectors. The fuel is cooler than the intake air and cools the intake charge, which will increase the air density. Given a specific volume of airflow through a motor, with a denser air charge more power will be produced and more fuel will be needed.

    Now my questions;
    If I tune my motor, with a rrfpr, to run an a/f ratio of 12.2 to 1 in 70 degree air and water, and the air and water temp’s increase to say 90 and 85, the warmer air and warmer water going through the intercooler will reduce the air density of the intake charge. Assuming the same rpm and fuel delivery a less dense intake charge will cause the a/f ratio to decrease. Will I need to reduce my base fuel pressure on the rrpfr to compensate for the loss of air density to maintain a 12.2 to 1 a/f ratio?

    Or, will the extra fuel in the warm weather, rich condition, actually help out by further reducing the temperature of the intake charge when the fuel is added by the injectors having the effect of increasing air density?

    Further, will the extra fuel, rich condition, be a positive by helping to keep heat in the cylinders down reducing the chance for detonation?

    Things that make you go hmmm.

    Mark

  10. #20

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    WFO, I come for the car-world also and I, too, have always been told to avoid 90+% duty cycle for fear of overheating the injector coils. However, my electrical engineer buddy assures me that the difference in heat generation between 90 and 100% DC is. . . you guessed it. . . only 10%. If it works at 90, then there's a slim chance that an extra 10% is going to kill it that much quicker. To add to this, I personally have never heard of anyone failing a fuel injector in this manner.

    Furthermore, it is possible that Sea-Doo is just designing for a shorter service life since you don't ride a PWC nearly as much as you drive a car. For instance, if you put 1,000 hrs on a PWC (that's alot), that's the equivalent of around 40,000 miles on a car (that's not that much).

    Mike

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