Powerband and fuel consumption figures?

[fsmyth]

Use a transmission. Gear it down to generator speed.
That being said, the 24 KW head is no load on the IDI, even at max output.
Add a few hydraulic pumps and move your water/oil/fuel around.
Get some work out of it

A small 3 or 4-cyl. would be more practical. Most of your running will be
essentially at no-load, so the engine will not be efficient.

 

[Andertusa]

The problem is, I already have the 6.9IDI( 2-to be specific) just hanging around and I don't don't wanna buy ANOTHER engine, when I already have them just sitting there. I was thinking of running the system with a complete cooling system, and oiling system, with selectable auxiliary cooling for both when the temps here climb into the 'HOT ' region.

 

[no mufflers]

if you had a truck radiator with a shroud and lock the fan I would think it would stay plenty cool. also these motors will almost run on anything, another benefit.