Quote from: gadget on December 04, 2020, 07:00:07 PM

I've been searching for an option for a low output CHP set, right around .5-1 HP. I'm looking for 300-600watts continues electric and heat output. Think small cabin type setup. I want it to run continues but be able to go a 25k hours between major rebuild(if possible) so I'm thinking low 100-200 RPM. Big piston / flywheel motor looks like the way to go.

So far, I'm thinking a listeroid may be the simplest setup, but I'm not sure what kind of power output at those speeds. I was also looking at a changfa but I think indirect injection would probably be more reliable at low speed vs the changfa direct injection. Its going to also run on oil.

Your looking for only 300 to 600 watts?
A listeroid is too large. It will never heat up enough. It will coke up, and cylinder will most likely glaze up with such a light load. And a gooey mess coming out of the exhaust.

If you can find an R-165  and slow it down I would think it might be a better setup. It's only rated to 3hp.
Running it at around 1800 might give you around 1.5 hp. With friction and losses in a belt setup it might get you to where you need to be.

Being an old hot rodder myself I certainly understand the thought patterns behind home brew gains from port modifications. Years ago there were some threads on here with all kinds of hypotheticals based upon spark ignition  racing engine theories that no more apply to a 600 rpm Listeroid than a 34a bra applies to Dolly Pardon. Cleaning up debris left by India doesn't need to be rehashed,, I don't think?  My gut on the port work deal is it would take a very a sophisticated set up with lots of instruments to prove any gain and and it would be trivial at best. As suggested those gains would also only be at the higher HP rating.
  As for a home brewed  porting test that would tell a much better story than smoke or eye ball inclinations a person could devise a means operate and hold the rack with the governor unhooked. Then apply a load and move the rack to give the desired RPM at that load. Then with an accurate tachometer, (or Hz reading if using a generator) start closing off the intake as Hugh originally posted. If said test does not lower the RPM until a significant portion of the intake is covered then port work will be a total waste of effort AT THAT RPM AND LOAD.   
Another area the book educated diesel hot rodders get lost upon is the fact that a diesel engine port is only handling air and it is drawing the same amount of air irregardless of load. The exhaust flow varies with load but the exhaust is seldom talked about.  Discouraging a person from experimenting is not my goal but a few basics need to be included if theory is going to be discussed.

Gadget, most people that try doing porting without understanding or proper schooling normally mess things up. The GM-90 head has a J figure casted in the pocket underneath the intake valve. Its roughly 1/4" tall. I agree that it's there to increase air speed and in turn also helps with swirling effect. As I wrote, this would also aid in mixing a gas that's injected in the intake. These engines, including the CS listeroid's dont need large valves or porting. Doing so will reduce air speed and in some instances it will effect performance and efficiency. Now, if there is casting pieces that can break than yes, get it out. But otherwise most of the time it's best to leave it alone.

Brings back memories of the Ford Boss 302 and 351 Cleveland engines. The intake valves and ports were too large for street use. The engines would gas foul the plugs so often. They would not run right until you were over 4000 rpm they ran great over 5000 rpm. This was the reasons why a the Australian Cleavland heads became so popular. Smaller combustion chambers and intake posts. They work great on street performance engines. The Aussie's got it right.

Quote from: gadget on December 28, 2020, 03:37:07 AM

Oh man, I'm at about 4500' elevation, it would be nice to find a few extra ponies

I don't know what you are running now but a 6)1 becomes an 8/1 with a change to aluminium piston and increase RPM. Also the stock bore is 114.5MM but India has 120, 127 or 130 MM bores as pretty much standard fare. Any of those will provide a nice increase. A change to the 034 type fuel pump will help governor responce with the larger bores and HP

FWIW  I reckon don't worry about the oil temp.  The engine is designed to run like that.  If it bothers you - just change the oil more often.  Those old English engineers knew what they were doing and that these old girls are still going 80 years later bears that out.  Just my $0,02