I am trying to decide whether the older model IHI 80NX midi excavator I have can actually run a brush cutter or mulching attachment on it (Fecon, RUT, Diamond, FAE etc). Typical brands of mulchers will say 18gpm or so is the minimum they use, with a few saying you can run it with as low as 12gpm. You have to wonder how long it would take it to recover at that power rate. Ok what does this spec chart actually say that my IHI has now (see pic)? Seems like is says there are (2) 3,550 psi 18.8gpm sections plus a (1) aux section that pushes 3,130 psi @ 14.0 gpm. I am aware of hydraulic horsepower and how to calculate that. If so, is there any upgrade you can tack on these machines to get a few more horsepower or gallons per minute flow rate? Seems like it might be possible, and all I would need is maybe ten more gpm. I am not for stressing the engine too much though as it might over heat it. Just exploring options. Don't be afraid to rain on my parade. https://www.kato-works.co.jp/eng/products/mini_shovel/html/pdf/80nx.pdf
I don't know the specifics of this particular machine, but it's a safe bet to say that the quoted figures will be theoretical bench-test numbers. By the time the flow has got through the valves and piping to the end of the stick, it will be less than that. The only accurate way I've found to confirm flow and pressure is to plumb a flow meter into the aux piping.
would that be something you can get off ebay?
Yes but they are expensive. The numbers quoted are just sales gimmicks. We would need a hyd schematic to work out what pump flows where. Also pumps wear out and flow decreases dramatically. Best way would be to get a hydraulic fitter to flow test it with there unit. You want to have more flow in machine then what the implement requires as movement of boom will slow the implement down otherwise. Flow of couplings also influence hydraulic flow.
As above. Probably best to find a local hydraulic company who can do it for you.
Sounds iffy to me because even if it can push 18gpm through the aux line something else will break from the the heat or strain. I get the feeling older small ex's were not serious about aux hydraulic lines for hungry work attachments as they are now.
Pulling 10 additional gpm from an excavator this size is a huge ask. I don't see it happening. I had an IHI excavator years ago. I don't know if the 80NX is the same but they used to run 4 pumps. They were great multifunctional machines in my view, because of that. If your able to get what the 18.8 the specs say, which it should be very close to that, I think I you would be happy with the performance. The PSI is good as long as you don't reduce it to run a thumb off the same circuit. Not to say that GPM doesn't matter because of course it does, but good PSI in a mulcher matters as well and you have good PSI.