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  1. #1

    Engine-Tech 3mm spacer & Fan Test!

    Today I tested Art's 3mm spacer & fan on a 2008 RXT-X. The boat is stock with the following exceptions (Riva 15-22 prop, Wings cut on stock grate and Intake tube disconnected before front baffle box).
    I tested boost with a Map Sensor wich measures absolute pressure.
    The base Map reading was -1.5 lbs of pressure so to compare to other posted reading from other members on the forum you would add 1.5 lbs to my results. The negative boost at rest is a result of altitude and temperature. Prior to changing the charger fan I measured the slip moment on the stock X supercharger and it measured 128 in/lbs. I don't know if this is enough to support the more aggesive fan but I have no shims in stock so it is what it is.

    I baselined the boat as above with the stock fan then pulled the supercharger and changed the fan (Total time between tests approx 90 min)
    The stock charger would only turn the engine 7900 RPM with 15/22 Riva.


    Stock Fan Boost RPM ---------Engine-Tech 3mm Fan Boost RPM

    -0.6 psi @ Idle ------------------- -.07 psi @ Idle
    2.9 psi @ 5000 ---------------------3.2 psi @ 5000
    4.6 psi @ 6000 ---------------------5.2 psi @ 6000
    6.5 psi @ 7000 ---------------------7.5 psi @ 7000
    7.4 psi @ 7500 ---------------------9.0 psi @ 7500
    8.0 psi @ 7900 ---------------------9.9 psi @ 7900
    -----------------------------------10.5 psi @ 8100

    This Fan appears to be the Real Deal, I don't know if it is any match for a Rude or C-Kit but it is a contender. I picked up 200 RPM and 1.4 MPH but I need to put more prop in the boat, give it more fuel and see where we go. I will do more testing tomorrow and post the results. Remember to equate to the boost numbers everone else is posting add 1.5 to all the above numbers (ie 10.5 + 1.5 equals 12 @ 8100).
    "Art" I think you have a winner, We appriciate the huge investment in time and capital to develope what looks like a great product. For those of you who don't know, I found out Art is a Sled guy who built this in his quest to make a billet Sled Turbo.
    Last edited by motorsport17; 07-13-2008 at 04:31 PM.


  2. #2
    iron head's Avatar
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    That sounds great .what fuel injector are you running a rrfp Thanks Gord

  3. #3
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    What was the AFR???

  4. #4
    I'm real lean, stock injectors and pressure!
    There is more power to come.

  5. #5
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    First of all...and I'm not raining on your parade or trying to be negative, but at idle, all superchargers create "negative" pressure. This is induced drag caused by the impeller. This negative amount is not added to your boost reading to get total boost.

    Your boost reading at 8100rpm was 10.5psi, so depending on where it was measured, that is the boost the engine is seeing.

    Secondly, I've seen the data logs on an X boat measured at 25hz(25 samples per second), and the injectors are maxed out, kaput, done. The only way your going to get more fuel for more boost is to upgrade the fuel pressure regulator, at a minimum, then go out and test again with an AFR.
    BTW, this has already been done. Your going to need bigger injectors also.

    I think that anybody that thinks they can just drop this wheel in there stock boat is asking for trouble. The engine will lean out and they will burn a piston.

    I truly appreciate the testing you've done to date, but I really thing you need to start data logging, or at least measuring AFR.

  6. #6
    You don't understand my post! With the engine off the MAP reading is Neg 1.5 PSI, the idle # is the measured Vac @ idle. The injectors are going full on about 8040-8080 RPM. You are right you need additional fuel with this setup. I have some 55lb that will go in this afternoon, it will be real rich below 7900 so I will need to pull fuel to compensate.
    You do need to add the 1.5 to get the total boost!
    Thanks

  7. #7
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    Quote Originally Posted by motorsport17 View Post
    You don't understand my post! With the engine off the MAP reading is Neg 1.5 PSI, the idle # is the measured Vac @ idle. The injectors are going full on about 8040-8080 RPM. You are right you need additional fuel with this setup. I have some 55lb that will go in this afternoon, it will be real rich below 7900 so I will need to pull fuel to compensate.
    You do need to add the 1.5 to get the total boost!
    Thanks
    I agree with just about everything you say, and yes, I do understand your post. However, the boost reading you get at max rpm is the boost the engine is receiving, period. There is no more boost lurking about because of this negative pressure at idle. ALL supercharged engines produce negative "boost" or MAP pressures at idle.

    I'm trying to explain this as best I can. Maybe I'm not being very clear, or there is some confusion. You have a MAP(manifold air pressure) gauge, and a boost gauge, or just a MAP gauge?? If your using just a MAP gauge, try also using a boost gauge and see what the number is. If your running 12psi, then your mph is off a bit. With the mods you have, and the correct a/f mixutre, you should be at 75mph with 12psi. Its really splitting hairs though. If you have 10.5 or 12, its not really important right now. What is important is what kind of improvements you will get when you put in the new injectors and get the a/f corrected. Also, if you get a Pro series ECU, that would really open things up.


    Here's what I'd like to see; I'm at about 72ish mph right now with just the Performer Kit, prop, and nozzle. How much more money is it going to cost me to go 75......what about 80mph????

  8. #8
    You still don't understand, put it this way if you are overdrawn $1.50 at the bank and deposit $12.00 you only have $10.50 in your account. Think of the charger as the deposit, it is depositing 12lbs but has to overcome the negative (read bad altitude) air of neg 1.5lbs. If this is too hard to understand I can't help you.

  9. #9
    Website may not be suitable for small children WOT's Avatar
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    Where are you locating the map sensor? Does it actually read in PSI or are you reading the voltage and translating that to boost?

  10. #10
    Reading boost in PSI, the port is between the Intercooler and the Throttle Body. That is why it is showing a boost gain @ idle. The whole point of the post is the net gain from the stock fan.

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