Production, there were quite a few built in the early 80’s.
Per Barrel crude oil prices: 1972 – $2.48 1974 – $11.58 1980 – $36.83
That was a disturbing trend at the time, leading to inventions like this.
Up to 20hp engines is design target of the S-80. The S-120 powered up to 300 CID inline 6 cylinder. SV-140 for V-8’s. Dry sawdust was the design fuel for all.
The S-80 makes plenty of gas for the 13hp. I think we could choke the gasifier some for cleaner final combustion at 13hp. Ideally it should run like a propane forklift, with little CO production. We did not have a CO monitor in the space. Seat of pants says we were making some CO.
Not sure what you ask by “hours”? Sawdust per hour, hours before regular maintenance, hours we have run the resurrected system?
Also, FYI, external surfaces at full output were about a “two Mississippi” to the touch. In some places, it is hot enough to make a person aware, yet not so hot as to be dangerous.