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pressure washer engine size

Discussion in 'Homeowner Assistance Forum' started by LarryF, May 26, 2010.

  1. LarryF

    LarryF LawnSite Bronze Member
    Posts: 1,171

    I'm not sure whether to post this here or in the power-washing forum, but I'm not in business, just another homeowner so I'll start here. I expect this will be moved if I made the wrong choice.

    I'm sure the unit I want should put out 3000 psi or perhaps more, but I noticed when looking at the latest Northern catalog that engine HP is not identified any more. I presume the manufacturer will match GPM and PSI with an appropriated size engine, but it would be nice to know approximately what it is in HP. My previous experience was with a 3000 psi unit that had a 10 HP B&S. I've not had problems with it, but it's pretty old now, and I doubt if it's still being manufactured any more. The ones I'm looking at provided by Northern seem to all have a GX160 OHV Honda engine. If anyone knows what that translates to in HP, would you share it with me?

    And if you are really into this pressure washing topic, Northern has a couple of units that use the name "Powerhorse" that look like they might be a great bargain, but I don't know anything about them.
    http://www.northerntool.com/shop/tools/category_pressure-washers+powerhorse+gas-cold-water

    They don't specify the engine or the pump manufacturers, but going by reviews in the above web site, most of those who bought it seem satisfied. I'd like to have your comments on these as well.

    Thanks
     
  2. twobroslawns

    twobroslawns LawnSite Senior Member
    Posts: 299

    160 cc will be 5.5 hp. The powerhorse untis are knock off hondas I believe. Look at the website under engine oil capacity and this will tell you about those engines. Last time I remember lloking it was something like .17 quart. Our 5.5 honda engine (on a mower) holds just over .5 quarts and our GX390 13 hp on our pressure washer holds signifacantly more.

    To me, PSI isn't important. Others may disagree, but I think GPM is more important. Like the 200mph blowers at homedepot that don't move anything and the Stihl 150 mph blowers that move tons of leaves - its CFM that matters. Our 13 hp has 3750 psi and 4.0gpm
     
  3. LarryF

    LarryF LawnSite Bronze Member
    Posts: 1,171

    Thanks! 5.5 HP doesn't sound like very much for a pressure washer. I'm going to do a bit more research before I leap.

    Anyone else want to make a suggestion?
     
  4. Brian E

    Brian E LawnSite Member
    Posts: 2

  5. LarryF

    LarryF LawnSite Bronze Member
    Posts: 1,171

    Even worse than I thought! According to this web site which shows the power curves:

    http://www.honda-engines.com/engines/gx620.htm

    the GX160 is only 4.8 HP and the GX390 is 11.7 HP. Maybe that's why the HP ratings are no longer provided in the pressure-washer ads. However, they both do have a 3-year commercial warranty.
     
  6. LarryF

    LarryF LawnSite Bronze Member
    Posts: 1,171

    I don't disagree that the GPM figure is important, but the PSI one is too, of course. For instance, you can get 5 GPM out of a garden hose without a nozzle, but without something to boost the pressure, you won't be able to do much with it. I presume that's why they call these things pressure washers. It looks like my choice will be this one.
    http://www.homedepot.com/webapp/wcs...langId=-1&catalogId=10053&productId=100644535
    The price doesn't seem bad to me considering the one I have now was purchased in 1998 for about $700, has a 10 HP B&S engine and puts out 3.5 GPM and 3000 PSI. It still runs and works well, but the new one will be for a son-in-law who has borrowed mine in the past and now had decided to get his own and asked my help in picking one out. This one is a couple of hundred bucks more, but it's 12 years later and the unit has an 11.7 HP commercial Honda engine and boasts 3800 PSI and 4 GPM. That'll be my advice, but if someone has a better suggestion, I'd like to hear it.
     
  7. twobroslawns

    twobroslawns LawnSite Senior Member
    Posts: 299

    Oh ya, thats a good one. Gooooooood choice:):):):clapping::clapping:
     
  8. PierreCiCi

    PierreCiCi LawnSite Member
    Posts: 34

    Pressure-washers are based on cleaning units. Example: 2000PSI @ 5GPM is 10,000 cleaning units. Cleaning Units = Pressure X GPM. It doesn't really matter how you achieve the Cleaning Units, pressure or gpm. The higher the Cleaning Units the better. In other words: 3000PSI @ 6GPM is better than 5000PSI @ 3GPM. I run two commercial unit that each have 3500PSI, but one is 7.5GPM and the other is 13.5GPM. Believe me when I say the 13.5GPM machine is tough to hold. It is mainly used for surface cleaning and rinsing. Hopefully I didn't confuse anyone too much.
     
  9. LarryF

    LarryF LawnSite Bronze Member
    Posts: 1,171

    Excellent point, PierreCiCi! And this chart is someone else's guideline of how many cleaning units are needed for various applications. Since you seem to be into this topic more than others, perhaps you will comment on it. I happen to think one should have a lot more than 5000 CUs to clean sidewalks and patio pavers, but I'm confident that the one I picked out, which will provide about 15000 CUs, will do that with ease.

    Pressure Washer CU.jpg
     
  10. PierreCiCi

    PierreCiCi LawnSite Member
    Posts: 34

    I only do sidewalks. Retail shopping centers. I started out with a 3500 psi/5.7 gpm unit about 8 years ago. The problem that I quickly ran into was not having enough volume to rinse after surface cleaning. That extra water volume makes a big difference. If you're only doing residential or your own home, you should be fine with the 15000 CUs machine.

    I don't have any experience on the units that Northern sells. I'm runing Kohler engines (38hp and 23hp) and General pumps on my units. The large unit is cold water only and the smaller one is hot/cold. The hot water is for the gum on sidewalks @ shopping centers. One other thing to note. Once you start going over about 18000 CUs the price starts jumping.
     

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