Questions Re Changfa Set Up

[daymik]

In my running days nobody ever accused me of being a sprinter but this is ridiculous. Having bought a Changfa 190 from Veggie 10 years ago I'm in the final stages of mating it with a TGE-DG-5KW generator. I've attached a pic of the setup to date.  I've got a couple of questions but I'll give some context first. We're on grid power and I installed a 2.7 Kw photovoltaic array as backup. This gen set would be further redundancy in the case we lose grid power and run into consecutive cloudy days. My expectation would be the generator would see limited run time (hopefully ). My skill set is in woodworking and anything made of metal has always been a bit of a puzzle to me, so please excuse the rudimentary nature of my questions. Fortunately I have access to very competent help with the electrical end of things so my questions relate to the Changfa end of the set up. My unit has the pressurized cooling set up with small built in fan. Is this sufficient for the occasional half day fun time? I'm aware that a number of you with similar set ups have gone to external cooling systems. The unit is situated inside my shop and I will need to run the exhaust less than 10 feet with 2 90 degree elbows to an external wall. What size and type of pipe should be used and can I leave the existing muffler in place and run on from it? And finally the Changfa has a 90 watt generator next to the cooling tank (pic attached). There is no lighting on this unit so what does this power? Thanks in advance for any advice offered and thanks for all the great content on the Microcogen site!

[Tom Reed]

The fan cooling system on my nm195 has held up to having the piss run out of it on 110 f days with no problems. The employee, not so much.

[mobile_bob]

the little generator is to provide charging current for the electric starter battery
and on some units the headlight that no one in more civilized countries have use for.

while the mufflers are generally pretty good construction, i would hesitate to connect any longer pipe to the discharge
as it will likely lead to cracking and failure of the muffler, and then you get to build a flange and connect direct to the head as you should in the first place.

some folks have had good luck with the oem radiators, others not so much, depends on how much run time you are likely to want to run, how much vibration, and whether you setup some sort of emergency shutdown in case of overheating.

myself, i would recommend a remote mounted radiator, so that it isn't having the crap shook out of it, an automotive electric fan and fan control, such as radiator/fan/control off a small car.  2 liter or less is fine.  i would remove the oem radiator and fan, and install a block off plate, fit a standard 195deg f thermostat, a radiator with a 7lb cap, overflow tank, electric fan, fan control switch, and a temp switch typical of what runs an idiot light that could cut off a fuel solenoid and drop the fuel rack to no fuel position should the engine sprout a leak and overheat.

most of the needed parts can be gotten cheap from a pick a part yard, off a wrecked small car(s).
the fuel solenoid and a bosch type auxilliary heater water pump can be found new on ebay for a reasonable price.
or the bosch pumps can be found on vw, audi and mercedes cars in the pick a part yard for about 5 bucks each. such pumps can support the cooling systems for up to about 15-20hp no problem.

it all comes down to what you want to do? how much run time are you looking at? and whether you are willing to babysit the thing.
done right you could start the thing and go shopping and not worry about coming home to a meltdown.

fwiw
bob g

[Henry W]

The engine is convection cooled.
Some things that you need to be careful with is not run antifreeze in warm days. Run water with a corrosion inhibitor. Antifreeze will raise the boiling point and a convection cooled engine can overheat. The attached picture below is taken from my Kubota EA300  series workshop manual.

I agree what Bob wrote.
I think by converting  a convection cooled system to a cooling system that uses a water pump, electric fan, 195 F. Thermostat and 50/50 antifreeze. Will be more reliable.

Henry


Must log in to view picture.

[mobile_bob]

the cooling system is what limits the hp output of the engine
if you use hopper cooling the s195 is limited to about 12hp at sea level max
ebullient/convection cooling is not much better, however a closed pressure system with water  pump
and radiator with tstat and fan control the engine can produce a couple more hp without overheating
and burns very cleanly.

what happens with ebullient/convection cooling is the formation of hot spots and formation of bubbles
which can lead to liner pitting if the engine is pressed into max power output for long periods of time.

with the water pump/radiator/fan the water is admitted to the lower section of the cylinder via the drain port
which promotes better and more even cooling with reduction in hot spots and bubble formation.

yes i ran 50/50 antifreeze and operate between 204 and 215deg F (might be 205 to 214, i don't remember)
and i would not be afraid to operate up to 220 deg F but the fan control and radiator capacity limit the max temp to ~214-215F

when the engine is allowed to run that hot with all the modifications to the cooling system, once up to operating temperature the tstat stays open and the fan controls the temperatures via the fan control switch, that is why there is the variation in temps of 204-215F.
the engine burns very clean with just a hint of gray smoke at well over 8kw output.

i am a firm believer in a closed system, even if it does add some complexity to the design.

there are those that like the simplicity of a hopper cooling system, and worry about added complexity.
if done right, i don't see the added complexity as something to worry about,  with a high temp switch/relay/fuel solenoid i don't see
there being anything to worry about.  if it overheats because of a leak, pump failure, etc. the shutdown system would step in and cut the fuel rack and shut down the engine before any damage could occur.

in testing i failed to manually turn on the water pump and ran the engine up to 280F with a blown head gasket the only damage to the engine, replaced the head gasket with a vastly superior gasket from "gaskets to go" and everything was good to go again.  i had not put the high temp switch/relay into the design at that time, had i done so the engine would have shut down at around 220F and there would have been no blown gasket.

point being the changfa engine's are very tough little engines, and can do a lot more than they can in stock trim.

bob g

[veggie]

The cooling system that came with the engine should be more than sufficient for your needs.
You could run it 24/7 if you want to. The belt driven fan moves a lot of air through the evaporator radiator.
Personally, I would not weld or hang any exhaust system to the existing muffler unless it is flexible and does not add weight stress to the muffler or the cylinder head connection flange.
With that engine, a 1.5" exhaust pipe is fine. (2" even better).
If you do connect to the existing muffler outlet, use a flex section before transitioning to longer lengths of rigid pipe.
These engines (and muffler) shake when running. That movement can stress fracture the muffler if the rest of the exhaust system prevents the muffler from vibrating with the engine.

veggie

[daymik]

Thanks all for the responses. I pick up a common back V-belt this week and so am close to a trial run.

[Henry W]

Your welcome daymik, looking forward hearing about the test run.

Henry

[daymik]

After spending way too many hours scouring the last 10 years of the Microcogen site to try and fill in significant gaps in my knowledge base I have to reiterate what a valuable resource the site is. Now while I've been able to answer a number of questions I had I'm still left with a couple and probably more to come once the unit is up and running. Henry you made a comment in the past with respect to priming the oil pump. How is this done? The Dingol generator needs to be run at 1800 RPM to produce 60 hz power. As the pulleys are matched the Changfa also needs to run at 1800 RPM.  How is engine speed measured and controlled? Is the stock govenor sufficient to provide consistent engine speed? Is engine speed simply adjusted to produce 60hz or is there a direct way of measuring engine RPM? Thanks for your patience with these basic questions. I'm within a day or two of a test run and will try and post a video.

Mike Day

[Henry W]

The Changfa S190 is similar to the S195 and others.  To prime the oil pump before the  engine is fired up I hold the compression release on and spin the engine over until the oil pressure indicator  pops up and shows the engine has oil pressure. Once the engine has oil pressure its than I spin the engine over until oil pressure indicator shows oil pressure and than release the compression release to start the engine.

The stock governor seems to work fine on most changfa engines.

Before putting any load on the generator. I plug in my fluke meter and set the generator frequency to 62 Hz. By adjusting the engines governor . Once 62 Hz is reached on the generator with no load, set the throttle so it will not move and than test run the generator. I never trust engine rpm's to get frequency
right. I always rely on frequency to get the engine rpm's to where they need to be so the generator will operate properly under load. Check voltage and if it's in range,  check the frequency again. If everything is good than it's time to do load tests. Start with and incandescent light bulb. If that test is fine than try a portable electric heater. If everything is well than increase the load and keep watch on voltage and frequency while adding load. If frequency stays at 58 or above under full load the governor should be fine.

Henry

[daymik]

First trial run of gen set. Sweet! Still need to wire in starter key and battery and tie the generator into the electrical systems inverter.
https://youtu.be/K22n5T67u9U

Mike Day

[Henry W]

Mike, thanks for posting the clip. The engine sounds good! Looking forward seeing and hearing more!

Henry

[veggie]

Nice work ! Looks good.
Runs strong and smooth.

veggie