I think it's an awesome looking jetter.Compact.Cuda says low rpm?how low is it.You got hoses and heads already?
I just ordered a new unloader and a psi gage to get some ruff idea of the real specs. After that I will order some new hose and other parts as well .
As far as RPM I will put my tach on it and see what is a good RPM for GPM and PSI for what I am going to be using it for.
My main goal is restaurant line with grease build up. I have a few accounts that need a higher GPM power unit, but it’s a pain to get my Harben into some of them.
your pump is the same one i have on my 18 h.p portable jetter and it does spec out at those #'s.
you need to install an accurate glycerin filled gauge at the pump/ unloader and also a test gauge at the end of the hose to read the pressure loss. you also need to size a nozzle based on actual flow.
get a high pressure ball valve/ 4000psi, and install it at the end of the tee with the gauge on it, to the desired size and length of hose you plan on using.
warm up you engine with no load and/ open valve.
bring the engine up to speed, i try to keep mine at 3000rpm or less.
throttle down the valve to create pressure. of course you need to tighten the unloader too/ raise the pressure. raise the pressure to the max. at your hose end based on the gauge and read the 2 gauges. the one on the pump and the one on your hose. this will show the pressure loss at flow.
direct the flow into a 5 gallon or larger bucket to catch the water. time the flow for 1 minute or 30 seconds and measure the water collected. usually holding the hose/ valve under water will keep it from blasting all over the place.
measure you results based on flow and pressure.
the flow should approach 5.6 as the pump is a positive displacement. as long as the rpm is maxed out based on the pump specs and engine specs.
i throttle down to 3000 or less to preserve the engine.
play around with the flow, rpm's and psi to get a good reading on the numbers.
when you have the real #'s then you can size the nozzles based on this.
or you can buy some sample nozzles and try. i would try a #4.5,5,5.5 and see which one is going to give you the flow and pressure you need.
too big a nozzle will give you flow, but lower pressure. too small will give you pressure, but less flow. just right will give you the monster you are looking for;)
the engines h.p will allow the pump to max out the flow and psi.
an undersized or weak/worn engine will not bring the pump up to pressure. as the pressure is increased, the h.p demand will increase. at 0psi, it only takes a couple h.p to flow the water. at 3500 it will take all 18h.p to keep it running.
hope this helps mike;)