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  • Ridgid 3300 psi pressure washer observations

    Thought I would post my unscientific findings regarding the Ridgid 3300 psi pressure washer that I just bought.

    I installed a Sendec hour meter/tach on it so I can keep up with the hours and not have to guess on when to change the engine and pump oil. I also bought a pressure gauge because I was interested in what the actual output of this unit is. There has been discussion on these forums relating to what Ridgid claims, and what Cat says the 3DNX27GSI pump's max RPM and PSI ratings are.

    I can't say for sure how accurate my numbers are because neither the gauge nor the tach are calibrated. Also the gague is a 0-6000 psi, with marks every 200 psi so it is impossible to be exact, especially with the vibrations and pulses of the unit when running.

    Manufacturer's Specs...

    RIDGID: 3300 PSI, 2.8 GPM

    CAT Pump: Model 3DNX27GSI
    Flow.............................................. ..............2.7 GPM
    Max. Discharge Pressure ..........................2850 PSI
    Max. RPM............................................... .3450 RPM

    Subaru EX21 OVH Engine:
    Max HP/RPM (Gross HP) 7.0/4000
    Continuous HP/RPM 5.0/3600

    What I found:

    The engine at full throttle WITHOUT the trigger pulled on the wand:
    Engine RPM = 3810
    Pressure reading is 3200 PSI.

    The engine at full throttle WITH the trigger pulled on the wand using factory supplied tips:
    Engine RPM = 3630 to 3650 (seems to stay settled more at 3630).
    Pressure reading is 2800 PSI.

    So, right off the bat the pump is turning 360 RPM over the max stated by Cat when the pump is dead heading and 180 RPM over the max when the trigger is pulled.
    The discharge pressure is pretty much right on the Cat rating of 2850.
    I don't really have a way to measure the flow rate. I may try running into a bucket and then weighing the bucket and calculating the volume by weight..



    I also bought a Powercare turbo nozzle (the 3000-4000 psi nozzle). Pressure drops to around 2500 psi when using it. Since the unit output is less than 3000 psi, I think I should have bought the smaller nozzle that is for units rated up to 3000 psi. I assume this would give me a smaller orifice size and thus increase the cleaning power of the rotray nozzle. The larger nozzle does however work well. It will chew up wood.

    Overall I am pleased with the unit and do not regret getting it. Obviously the 3300 psi that ridgid claims is only close when the unit is dead heading. If it would put out 3000 with the trigger pulled I would be elated because that I what I really wanted. With that said, this was bought for homeowner use, and has plenty of power..
    Last edited by jimed1; 07-13-2009, 03:40 PM.

  • #2
    Re: Ridgid 3300 psi pressure washer observations

    jimed-

    i have also installed a gauge, at the pump, of the 3300 psi and had the same results, with regard to the pressure. However, I never considered the rpms exceeding the pump max. Will this destroy the pump if it is continually exceeding it's max rated rpms?

    thanks much for the info.

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    • #3
      Re: Ridgid 3300 psi pressure washer observations

      I really don't know. I wouldn't think it would hurt it too much, but you never know. I am going to trust that the Cat and Ridgid worked together to design this unit or that at least some communication took place between them when Ridgid decided to build these. Hopefully they decided on the engine first and then asked cat for a suitable pump. I can't imagine that Cat would recommend a pump knowing that it wouldn't last. That would damage their reputation if the pumps started failing early because the were a bad fit to the motor.. Of course they may have intended that the engines be set up to not exceed 3450 RPM and Ridgid dropped the ball on proper setup at the factory. Who knows?

      Jim

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      • #4
        Re: Ridgid 3300 psi pressure washer observations

        Thanks for taking the time to observe and then posting your findings. Funny how manufacturers put a certain MAX number on a product then the company selling it usually inflates it one way or another. Later!

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