Changfa S195 Radiator question

[veggie]

My R195 has a factory evaporator radiator.
I am wondering if this is optimal for best performance.
The setup seems like it would over cool the engine.
With the fan blowing all time (Both on the stock version and on my electric fan version), the system looks like it would provide too much thermal transfer if the engine is running any anything but full load.
If the system can cool the engine at full load, then would it be over cooled at 1/2 load or 3/4 load.?
I suspect they wanted a simple system that would work in any situation, but if I plan to run the engine at 3/4 load on an alternate fuel, I want to keep temperatures near optimal for clean combustion.

Now, some say to fill it half way and let the steam condense in the rad tubes, others say fill it all the way and allow therosyphon to work.
To me it looks like it should be filled all the way. Because if not filled all the way, there is no way to know how much water is in there.

Anyway, do you think it would be better to remove the rad and go with a plate/thermostat setup ?

[Tom Reed]

I run one with a radiator like that too. My thoughts are that any thermosyphon system is inherently self limiting. The reduced temp differences under low load induce reduced flow. You can test this by measuring the temp of the exhaust air under different loads.

[veggie]

I run one with a radiator like that too. My thoughts are that any thermosyphon system is inherently self limiting. The reduced temp differences under low load induce reduced flow. You can test this by measuring the temp of the exhaust air under different loads.

Hi Tom,
On your model, the fan speeds up or slows down with engine speed. So maybe it is self limiting.
But, say you are running fast (maybe 2000 rpm) and the engine is only 50% loaded.
The fan is moving a lot of air through the rad, but the there is not much heat being generated.
That's where a thermostat system would help.

[Henry W]

In the manual on my Kubota EB300 it gives the coolant Capacity. It fills radiator about 3/4" from the top. It also states not to use antifreeze in hot weather. Antifreeze will raise the boiling point to a dangerous level.

It also gives different mix percentages for different temperatures.

A simple system but, it needs constant monitoring for reaching optimal operating temperature. 

The coolant system will be changed to a water pump system with a different radiator.

[Henry W]

I run one with a radiator like that too. My thoughts are that any thermosyphon system is inherently self limiting. The reduced temp differences under low load induce reduced flow. You can test this by measuring the temp of the exhaust air under different loads.

Yes, but I think the systems don't keep the engine at optimum temperature unless fully loaded.

Your correct. The engine needs to be close full load to reach operating temperature.

But, when its 100°+F the engine has to be watched for boil over.

The Kubota almost reached that point almost a month ago when operating it near full load.

It's to temperamental for me.

[Henry W]

Veggie,

I've been thinking. Since the engine is not set up to produce full power, it might be possible to use a thermal switch to turn the fan on when its needed. With no air flowing through the radiator, the temperature should rise until the temperature switch turns on the fan. The only modification that might be needed is a plate made that mounts between the engine and radiator. The plate might need to be 1" thick so a hole can be drilled and tapped on the side to screw in a temperature switch.

Possibly drill and tap another hole or two for possible multi speed setup, or redundancy backup. It should not be too hard to do. These holes can be plugged if not used.

Oh, you will also have the ability to screw in a zinc anode to sacrifice itself from corrosion. A good way to protect the engine cooling system.

Henry

[playdiesel]

The only one own that has that set up is an R180 that I run a saw with and it does over cool the engine at least in my loadings. My redneck fix was to cover part of the radiator. My stand by set has a 1115 and I made a plate. The first version was 3/8 and I had to increase it to 1/2 so it was ridged enough to stay sealed on top of the block. I agree with Tom that there is zero need fir a thermostat with the plate if the circulation is via thermosyphon. My engine warms quickly and doesn't circulate until hot. I have a sender in the plate that controls the 12V fan. By the way the alternator installed behind the flywheel will not keep up with the amps the fan uses. I just use a battery charger to keep the battery up while running. Seemed easier than mounting a 10SI?

[veggie]

@Henry

Good idea. If not using the heat elsewhere (requiring a plate and hoses) perhaps I can re-install the snap-disc switch on the side of the radiator to control the fan.
The snap disc temp switch that I have is adjustable with a dial. I would set it to the appropriate radiator wall temperature.

[Henry W]

That is exactly what I was conveying. I was thinking of using an automotive temp fan switch. A mater of fact I was thinking of two. It's good to have redundancy in case one gives out. A plate with 4 or even six ports, future growth would be a piece of cake.

Just a thought, a liquid cooled oil cooler would be a nice touch. It would keep the oil at proper temperature. This type of oil cooler will dump excess heat in the cooling system.

[mobile_bob]

My R195 has a factory evaporator radiator.
I am wondering if this is optimal for best performance.
The setup seems like it would over cool the engine.
With the fan blowing all time (Both on the stock version and on my electric fan version), the system looks like it would provide too much thermal transfer if the engine is running any anything but full load.
If the system can cool the engine at full load, then would it be over cooled at 1/2 load or 3/4 load.?
I suspect they wanted a simple system that would work in any situation, but if I plan to run the engine at 3/4 load on an alternate fuel, I want to keep temperatures near optimal for clean combustion.

Now, some say to fill it half way and let the steam condense in the rad tubes, others say fill it all the way and allow therosyphon to work.
To me it looks like it should be filled all the way. Because if not filled all the way, there is no way to know how much water is in there.

Anyway, do you think it would be better to remove the rad and go with a plate/thermostat setup ?

a little late to the party, but here goes

back about 15 odd years ago, i built the s195 based trigenerator, the engine driving an st7.5, twin 110-555jho alternators and a sanden rotary a/c compressor for refrigeration use.

i removed the fuel tank and the water tank, and installed a block off plate, and then found a tstat housing off a small honda car 4 cylinder engine, drilled an 1/16" hole in the perimeter of the tstat, inserted a tiny cotter pin to rattle around and keep the hole open.

the radiator i used was from a 1.8 liter nissan sentra, along with the fan and fan switch that came off the same car,  1987 model if that makes any difference.

i used a bosch auxilliary heater pump from a vw (used on audi, mercedes german cars) the pump runs anytime the engine is running. very little water goes through the tiny hole in the tstat while the engine is warming up.

once the engine reaches 195deg the tstat is fully open, and at 214 deg (F) the fan switch turns on the fan, the switch opens when the temp lowers to 205F and then cycles from 205-214 deg F

the radiator is oversized but makes no difference because of the tstat keeping things above 195f and the fan then keeps things cycling between 205 and 214F setpoints.

at full engine loads the fan from memory cycles every 3-4 minutes, running for maybe 20seconds per cycle, at part loading the cycling stretches out to iirc about 6 minutes and 10second run times.

this allows the engine to burn exceptionally clean up to just over 8kwatts load, that at near sea level and 70F ambient temps.

i also used a 7 lb radiator cap and an overflow tank so that the system recovers whatever coolant is displaced due to expansion in the system.

fwiw, the exhaust heat exchanger at full load would raise 60gallons of water from 70f to 140f in right  at one hour, i don't recall the calculated heat recovery in btu's but i was quite happy at the time with the results.

i suspect that the cooling system could also reject similar amounts of btu's, which means that the system could make a serious amount of btu's in hot water for whatever one might have a use for.

also of note, i used twin fuel solenoids, one to pull the engine up to 1800rpm the other for 1000rpm use, both of which were grounded through a relay that was controlled by a temp switch that would open at 220f and shut the engine down.

while i wouldn't worry about twin fan control switches (failsafe operation) because of the relative expense, i would however put two of the overtemp switches in series on the solenoid relay. simple idiot light switches are plenty good enough for controlling a grounding relay for the solenoids.

having said that, at first i thought maybe the sentra 1.8 liter radiator and fan would be way oversized for proper operation, in application they work just fine.

btw, the water for the aux heater pump which has 5/8" heater hose barbs, i draw the water to the pump from the lower hose of the radiator, (reduced from 1" to 5/8") then from the pump to the drain cock on the bottom of the block.  i think that one might find that one of these pumps could easily handle the needs of up to 20 and maybe 25hp.

fwiw, and maybe some part of my experience would be useful

bob g

[veggie]

Great information Bob, thanks.
Interesting to know that the o-rings on the cylinder sleeve can handle a 7 lb radiator cap.
I just took a look at the Changfa cap that came with the engine.
It has 0.50 stamped in it. I presume that means 0.5 atmospheres? or 7 psi. 

veggie

[mobile_bob]

fwiw

in testing one day i forgot to switch on the water pump,  everything breadboard connected for testing and all that.

before i knew it, the engine was running with a temp reading on the Stewart Warner manual gauge, "265F"

and the engine was making just a bit of smoke, so i quickly shut the old girl down and left it to cool off naturally.

came back later and it would not start, however it would shoot coolant out from between the head and block, indicating a failed head gasket.

removed the head, and found the fire ring shot, and of course the steel core fiber gasket blown out

why it continued to run under load, still amazes me to this day???

long story short, the s195 i have is an idi engine, and i found that the modern "print o seal" black carbon gasket that fits the s1100 di engine is a direct replacement and far superior to the oem s195 gasket.

cleaned everything up, installed a new gasket and back to work again. 

so any concern regarding the liner orings is not really something to worry about.  even after hitting 265F under load the orings still seal just fine at 7psi.

btw, i am not suggesting that these engines should be ran up to 265F, but apparently it won't kill one, that is if it retains its coolant,  the added capacity of my radiator and piping likely retained enough coolant to assure that the liner/piston and orings could survive the abuse at least once.

i think these engine's have a lot of potential for some serious testing, what testing i did clearly showed me that with an enclosed tstat and fan controlled system allows these engines to produce substantially more power and burn cleaner doing it.

i also believe the 12hp continuous duty rating (s195) is based on hopper cooling, using plain water, under such conditions, it is likely that the system would be boiling pretty hard at anything more than 12 hp output.  so i think that is the limiting factor, and if so i think it applies to the other families of engine's, larger and smaller.

bob g