First and foremost id like to thank everyone that is constantly contributing here. This forum has opened so many unexpected rabbit holes leading to so many thing that i had no idea about.
The question at hand, ive found two different formulas for calculating the hp requirement for a pump. One of which is gpm x pressure x 0.0007 = hp required. Using that formula it looks like i could slap a 4 gpm pump on the gx200 i have on the shelf and run about 2300psi max. Am i completely off here? If this has been done just tell me im an idiot and my search skills suck, lmao. As i havent been able to find much on gx200s being used.
More realistic formula is psi X gpm / 1100.
Using that formula if i drop my expectation to 1800psi it would be in range. However, isnt 1800 going to be just a bit too low for any concrete work? Im thinking surface cleaner wouldnt have quite enough to be effective. I do believe some of the 8gpm pumps ive seen are only in that pressure range…
You aren’t really going to be able to wash anything with that engine. At least not anything that makes money for you.
That’s because most don’t use a GX200 for pressure washing on here. Don’t forget to factor in pressure loss through 200’ of hose. That puts you down to about 1500 psi. That doesn’t take into account anything else like fittings that could cost you some more psi. If someone was only getting 1800 psi on a pump they probably only use it for house washing. You could do some other stuff like wood but you’d run into some issues with concrete or other higher pressure jobs. I think the guys that had a lower pressure 8 gpm had other machines to fall back on for concrete and other work. I’d say a GX390 is about the minimum for an engine to make money. Maybe you can use the 200 for a trash pump if you ever need to transfer water or put a high flow low pressure pump on it for roof washing.
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Im thinking with where im at i may just be best off trying to sell it off and putting the money toward a real washer. Thanks for the input guys!
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