Honda GX390 engine - 11.7 HP and a belt drive Cat triplex pump. 4,000 psi at 4 gpm. I added the included quart of 10w-30 oil, some gas, hooked up hoses, ran water through the pump, etc. The Cat pump came with oil so nothing to do there.
The engine easily started on about the third pull - it was easier to start than my 5 HP residential Honda powered 2,500 psi pressure washer. I was quite amazed.
The frame is aluminum and the washer is nicely balanced on the large pneumatic tires. What a difference between 2500 and 4000 psi - wow.
Pressure Washer Direct shipped this out right away after I ordered it - maybe so I wouldn’t change my mind and cancel the order This was expensive but I think I made a good decision and I’m quite pleased, at least so far.