Like you, I need to run all sorts of equipment via the Listeroid. This is mostly due to power outages after hurricanes, but also when I feel like running off grid. As a person with an aeronautical engineering background and a capable fabricator, I did my best to achieve a quality system. I fell quite short of the ultimate goal of smooth power, but I still have some tricks to try.
At a glance: Bluprinted and balanced 20/2 Listeroid with extra heavy flywheels and internal crankshaft counterweights, 15KW ST head and extra heavy pully assy.
My neighbor has a standard 16/2 with a 10KW ST head. He had some significant flicker issues. This is why I chose to double the flywheel inertia and add a much heavier pulley on the gen head. What I ended up with is belt "chirp" as the pulley inertia is enough to resist the engine's power stroke, in addition to just slightly less annoying flicker.
Not one of my UPS's is fully happy with the Listeroid power. Some will accept the Listeroid/ST power only when a significant load is applied to the ST head, such as running the 5 ton central air. Some of the UPS' will not accept the power at all, even when adjusted to the "least sensitive" setting. The microwave groans too. Plus, the Listeroid governor is not up to the task of accurate frequency control. The best I have seen is about 1.5 HZ from 25% to 75% load. Maybe 2.5 HZ min to max. Freq self damping becomes a problem with closer control. The Listeroid Gov is not designed with good RPM control in mind, with a spec of 6%.
However, the engine will run well on anything I feed it, it will start the 5 ton AC without any problem, is fairly thrifty on fuel and will run all day without attention. It also starts right up without any problems.
My current plan is to install an additional 100 pound large diameter gen head flywheel to further reduce the power stroke induced flicker. I also plan on installing a capacitor on the Z winding to smooth out the nasty sine wave a bit. Will this fix all the issues? In my case, it is likely to get me close to what I need.
By the way, my 11 HP portable 5500 watt generator has no issues with the UPS' and does not display much flicker. Also other people point out that a 3600RPM gen head produces even more flicker related problems when used on a Listeroid.
I hope this helps you decide.
Would I do it again? Probably not. I would choose at least a 3 cylinder diesel running at 1800RPM coupled with a modern gen head. A neighbor purchased a 30KW Mitsubishi 4 cyl quiet diesel genset for 9K. I have seen smaller units, fully enclosed with fuel tank for 5K AND they come with a 5000 hour warranty!
Did I enjoy the project? Yes! I like to build stuff.
Am I happy with what I ended up with? Yes! It sure looks nice (fancy paint job) and it is fun.
How long do I expect the engine to last? 5000 hours between overhauls, based on the visible wear rate.
Does it serve my needs? Yes, for the most part.
Chris