Pete C. wrote:
Some Guy wrote:
I'm looking at a few gasoline-powered pressure washers.

Naturally, the typical specs a

a) the hp rating of the engine
b) the gpm
c) the psi

So my main question is - are these numbers fudged, or have a wide
accuracy range?

What is the minumum rating (in terms of gpm and /or psi) that make it
worth while to actually buy one of these things?

The range I see are from 2 to 4 GPM, and roughly 2000 to 4000 psi.
Engine HP from 6 to 13.

Your answer should not include "it depends on what you want to wash".

I want to know if a washer that does 2 gpm @ 2000 psi has only half the
"cleaning power" as one that can do 4 gpm at 4000 psi (ie does the
cleaning power scale linearly with these numbers, or geometrically or
exponentially).

They are independent.

PSI = Cleaning power as it dictates the water velocity and thus cleaning
force.

GPM = Cleaning efficiency as it dictates the volume of high pressure
water and therefore the area that the cleaning force can be applied to.
The smaller the area, the longer it will take to clean a given surface
area, just like a 22" lawn mower vs. a 60".

Well, that ain't exactly the whole story either...

The nozzle tip geometry has a great deal to do w/ the actual application
of the water to the surface and the effect thereon for whatever the
actual PSI/GPM ratings are...

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