Adding extra engine block mass to a China diesel

[rcavictim]

I note that there is a demarcation line at the model 180 horizontal, single cylinder cast iron hopper cooled China diesels where this size and smaller do not employ internal spinning counterweights and the models 185 and larger do.  I am told that engines with the countershafts are physically much heavier and beefy in their construction, giving some the impression that engines like my light weight JD175 should be considered no more than a toy. Toy or not, my engine runs very well and I would like to see if I can get long service life out of it for a battery bank charging application up to 2 kW.  I have improved the internal oiling system.  I have about 150 hours on the engine now direct driving a 2 kW ST type alternator head at 1800 RPM (the engine is rated at 6.6 HP@ 2600 RPM).  It will make 2 kW at 1800 RPM with black smoke,  1700-1800 watts no smoke.

I have been thinking of cutting up some one or two inch steel plate and making some bolt on mass that I could attach with bolt fasteners to my 175 engine block as an experiment.  I want to see if this makes the engine happier at lower speed operation for one example.  I would be interested in comments on whether it may also help the engine last longer.  I suspect it will run smoother.

This question sounds like it will breach the same territory that was discussed to death with great contention about the Listeroid and a ton-o concrete bolted underneath.  I am thinking of adding in the area of 50-70 pounds or so.  No more.  That is about 1/3rd to 1/2  of the engines present mass.

[GuyFawkes]

block MASS if added indiscriminately can make matters worse, unless it is added to the mount the engine is attached to.

rotating mass is good too, the old rule of thumb was that a 12" crank handle an average man could wind up up to a ton of rotating mass without too many problems.

I once saw and started a 1.5 hp 700 rpm lister d that was coupled to what must have been 3/4 of a ton of flywheel mass (an old press brake flywheel) which was used to store up energy for a big (AFAICR IRO 200 ton) press brake, that D would make a quality electric motor feel rough, after the brake was tripped it took a good minute or so of full throttle to wind the flywheels back up and the governor tripped the carb back to tickover

as geno has discovered, extra flywheel mass is always a good thing, and for stationary engines running at constant rpm it is quite hard to get too much of a good thing, I suspect around 3,000 lbs on a 6/1 would be getting near the point where windage and bearing losses became significant

[rcavictim]

block MASS if added indiscriminately can make matters worse,

So you are saying if I hadn`t decided to tell the world I was gonna try this I probably would have been OK?  Next time I have a rush of s*it to the brain I`ll try to be more discriminating.   

I have considered increasing the mass of the aternator side of the lovejoy coupling with an additional flywheel.  This thing presently  has terrible light flicker. I suspect pl;ay in the coupler to be part of the cause.  I may be able to adapt a truck v-8 gas engine flywheel that I have from a big gas sucking Ford engine like maybe a 429.  I found a flywheel, clutch and pressure plate assembly in perfect shape in a Ford parts box at the dump and it somehow jumped into my car as I was about to leave.     I`ll have to determine that it is not purposely out of balance to balance the crank it was made to attach to.

If one puts too much flywheel mass on too light an engine it will be an invitation for considerably increased torque jerk every time the engine fires.  It seems to me in this respect that the mass of the engine and of the flywheel need to be in some ratio of equilibrium.

[Doug]

Might I sugest a fly wheel off something like an agricultural tractor?

Some use very heavy ones, all include a ring gear.

Doug

[rcavictim]

Might I sugest a fly wheel off something like an agricultural tractor?

Some use very heavy ones, all include a ring gear.

Doug

Sure go ahead.   

Actually I am trying to acquire a very heavy flywheel off a MF (IIRC) bailer that my neighbor is scrapping out that runs on the machine end of the PTO shaft at 540 RPM.  No good for this job (too large to spin at 1800)  but I`m still trying to get a hold of it for possible future use.  Another fellow I know has a farm scrapyard full of vehicles, and farm machinery going to rust.  This is where I scored my rusty and seized 1966  Petter PJ-1, which breathes fire once again.  He probably has just the flywheel I need there somewhere.

[dkwflight]

Hi RCAVictim

Lok at spinning that flywheel at engine speed. I think if you do that the engine would be much more speed stabile.
Dennis

[rcavictim]

Hi RCAVictim

Lok at spinning that flywheel at engine speed. I think if you do that the engine would be much more speed stabile.
Dennis

That was my plan.  I explained that in my first post. my alternator is directly driven 1:1 with a straight coupler.  For battery charging I don`t have to have 60Hz so I can actually slow the engine to save fuel and wear below 1800 RPM with that 1:1 setup if my charging power need is reduced to say 1 kW or less.

I agree with you. Thanx.

[buickanddeere]

  Two Cylinder flywheel from a John Deere  R,80,820,830 or 840 might work? They mount on a round shaft with a couple of square keys to drive it.
   The other two cylinder flywheels mount via splines so they maybe a challenge to use.
    The side mounted flywheels on some balers spin faster than 540rpm front mounted flywheels.

[rcavictim]

  Two Cylinder flywheel from a John Deere  R,80,820,830 or 840 might work? They mount on a round shaft with a couple of square keys to drive it.
   The other two cylinder flywheels mount via splines so they maybe a challenge to use.
    The side mounted flywheels on some balers spin faster than 540rpm front mounted flywheels.

Thanx for the ideas, but those front 540 RPM wheels are manly aren`t they!      Insert Tim the Toolman visceral animal sound of endorsement  here. 

[oliver90owner]

Don't want to be a killjoy but remember you can't just keep hanging weight on a shaft.  The flywheels mentioned above are probably on shafts with considerably larger cross section area and supported by some serious inboard bearings or bearings on either side, close to the mass in both cases.  Take care.
Regards, RAB

[rcavictim]

Don't want to be a killjoy but remember you can't just keep hanging weight on a shaft.  The flywheels mentioned above are probably on shafts with considerably larger cross section area and supported by some serious inboard bearings or bearings on either side, close to the mass in both cases.  Take care.
Regards, RAB

RAB,

You are correct Sir!  I was not proposing putting one of those very large and heavy flywheels on the alternator shaft for the reason that at 1800 RPM they would be oversped.  If speed was not an issue then yes, I would still not for the reason you give.  That automotive engine (truck) flywheel I have is possibly still an option here if as showed a concern for earlier, it is self balanced.

[Geno]

If one puts too much flywheel mass on too light an engine it will be an invitation for considerably increased torque jerk every time the engine fires.  It seems to me in this respect that the mass of the engine and of the flywheel need to be in some ratio of equilibrium.

The SOM flywheels on my Indian 6/1 seem to smooth out the compression/power transition and therefor torque jerk. Flicker is mostly gone by eye which seems to confirm this. I'll be testing the flicker with a scope soon.

http://www.genedevera.com/temp/IMG_0389.jpg

Thanks, Geno

[M61hops]

Hi RCAvictim.  I replaced an 8HP briggs & Stratten with a ChangFa 175A on an old 2.5KW genset.  It jumped around fore and aft too much with each power stroke so I added about a 100LB piece of steel plate under the motor and that smoothed it out a lot.  It could probably use even more weight but its hard enough to roll over my door sill as it is!  Since I don't have an electric starter I have thougt that adding more weight to the flywheel would make it easier to start and probably smooth out the whole setup also.  I'd like to mount an automotive flywheel and starter to the set but that would mess up my belt drive setup so I have been using a slow but powerfull electric drill to start it.  With the motor running at 2400RPM and the generator at 1800RPM it is happy at 2500W and is starting to make black smoke at 2900W.  I think the heavier the frame and flywheel the better if you don't have to move a genset.  I think I've heard that someplace also!  Leland

[rcavictim]

Hi RCAvictim.  I replaced an 8HP briggs & Stratten with a ChangFa 175A on an old 2.5KW genset.  It jumped around fore and aft too much with each power stroke so I added about a 100LB piece of steel plate under the motor and that smoothed it out a lot.  It could probably use even more weight but its hard enough to roll over my door sill as it is!  Since I don't have an electric starter I have thougt that adding more weight to the flywheel would make it easier to start and probably smooth out the whole setup also.  I'd like to mount an automotive flywheel and starter to the set but that would mess up my belt drive setup so I have been using a slow but powerfull electric drill to start it.  With the motor running at 2400RPM and the generator at 1800RPM it is happy at 2500W and is starting to make black smoke at 2900W.  I think the heavier the frame and flywheel the better if you don't have to move a genset.  I think I've heard that someplace also!  Leland

Thanx for this.  I decided to accept reduced electrical output associated with driving my 175A at only 1800 RPM (rated HP occurs at 2600) with the thinking that the engine would give extended service life at the lower RPM and would use less fuel per unit of time.  The selection of 1800 RPM is due to the direct drive method chosen to drive the alternator head, improving efficiency by reducing the mechanical losses associated with belts and pulleys, significant enough to be a factor for my application.

It is a shame that the output shaft on these style engines is not available to us.  The only options are to place a belt around the perimeter of the flywheel  (only on non electric start versions) or bolt a coupler to the center of the flywheel where the factory supplied belt shieve attaches.  It is a challenge to add a second flywheel safely to this type of engine.  In fact it may cause a broken crankshaft if one does so unless some sort of harmonic dampener is inserted between the crankshaft + factory flywheel and the added flywheel mass.

Just as a thought, I suspect your difficulty in crank strarting your engine may be born from the fact that you have the belt drag on the engine spinning the alternator while cranking.  I have no trouble hand crank starting mine as it has a directly driven in-line alternator.  No frictive belt losses.

[M61hops]

Hi again RCAvictim.  I was suprised at how much drag the belts added and that is what made the difference in being able to hand crank start the motor.  Without the belts on I can just barely hand start it and with the belts on I can't.  I thought of direct drive and I'm sure that would increase engine life but it was cheap and fast to use belts.  I wanted to slow it down to 2400 to try and increase engine life and the pulley from the motor mounted on the generator shaft gave me the ratio to do that using the double pulley that came with the motor.  I had to buy a $0.75 bushing to make the Briggs.  motor pulley fit the generator shaft, and I was up and running but with a lot of shaking back and forth.  The ChangFa is way too noisy so I'm setting up a listeroid set for a permenant back up genset.  I really love the design of the ChangFas and also the Petteroids but the Listeroids are way, way quieter to start with.  Leland