r195 changfa lowest speed

[mobile_bob]

anyone have a 195 changfa out there that has tried to run it at low rpm?

if so how slow can you run one and still get useful power and relatively decent operation?

bob g

[rcavictim]

Bob,

Where were you a year ago when I was pestering the group for answers to this question.  I am engaged in an interesting experiement right now.  I have a tiny JD175 (~340 cc).  6 HP @ 2600 RPM.  I have been using it DD coupled to an 1800 RPM, 2 kW Kohler head.  It is very happy at 1800 and can make 2 kW, but no more.  Ignoring frequency I have used this setup to test the engine into resistive loads (frequency insensitive) at still lower speeds.  This engine just does not appear happy below about 1300 RPM.  At 700 RPM or so it sounds like it is gonna hurt itself.  The flywheel supplied is not adequate for lower speed operation.  Even at 1800 I have significant lamp flicker.

I recently acquired a massive 180 pound, 19.5 inch diameter by 5 inch wide stover style flywheel off a hay bailer.  I am in the process of putting it on a jack shaft on ball bearings that will allow it to directly coulple to the stock flywheel with very stiff rubber couplers (just there to provide harmonic dampening and reduce the peak shock load to the crankshaft so as not to bust it).  My power will come off the other end of the shaft with a V-bely pulley to a 2 kW, 1800 RPM DC generator I have.  I figure at 1000 RPM, the safe max speed of this massive flywheel I will be able to make about 1 electrical kW with this engine setup. That will be good as a 24/7 battery bank charger for my off-grid package.  I will be in a position to evaluate the really slow speed regieme of this engine then.  At 500 RPM it is going to use next to no fuel.  Forget having enough heat output to cogen ha ha.  I have improved the internal oiling system (I added a scoop dipper to the lower rod cap) so that I will get sufficient lubrication at such slow RPM (I don`t think that would be the case with a 175 stocker).  I also plan to put massive iron ballast attached firmly to the crankcase to facilitate the low speed operation.

We shall see!

If this works well I may do this to a new Changfa 1115. From what I have seen it appears to me that the Changfa is a way better machined engine than the Listeroid and cheaper too.  At 1.2 litres displacement it could make about the same amount of power as a 6/1 at the 600 RPM mark and with my added flywheel ad engine mass mod could possibly outlast a listeroid between major overhauls.  I just don`t have a couple of grand spare to purchase a `roid, although I`ve been jonesing for one somthin` bad.   

I plan a thread on this project as it develops.

[mjn]

Back when I was working on my computer controller for my 195, I picked 600 rpm to warm up the engine after starting.  When running at 600 rpm, the engine hammers quite a bit.  When I upped the speed to 1000 rpm, it seemed to smooth out and not put so much load on the lovejoy connector.

I haven't tried to see how much power I can get out of it at that speed, but 1000 RPM seems to be the lowest reasonable speed for this engine.   A larger flywheel like rcavictim has will probably make a huge difference.  (The flywheel on my 195 probably weighs 1/4  of what one of the flywheels on my 6/1 metro weighs.)

[mobile_bob]

Guys:

thanks for the input

i was hoping for ~1200rpm for a low speed setting, and would like to get maybe 5hp(max) out of it at that speed

i seemed to have misplaced my hand held tach, and am not sure how fast my 195 run's or rather how slow it will go before
it just hammers to hard for my likeing.

it now looks like maybe 1200 is doable.

thanks guys

bob g

[okiezeke]

I'm running my changfa clone at 1800, direct coupled to an ST15.  It runs smoothly down to 800-900 or so with no load.  I'm looking for more load to see what I can produce at 1800.  So far only loaded to 5KW with no problem.   Hoping for around 12KW.  Will see.
Zeke

[ZackaryMac]

rcavictim
That flywheel from a bailer...you do know they were designed to run PTO speed, or 540rpm, yes? No doubt they have a certain amount of overspeed designed into them, but you are looking to almost double it's designed operating speed, at a constant rate.
I'm not trying to interfere here, but I've seem them on bailers in the shop at work. The thoughts of that flying apart at speed is a scary thought indeed. You could run the engine at 1000 rpm, and run the flywheel at 500rpm through double or triple belt pulleys, and still have the flywheel effect.
Sorry to go on, I was just imagining the "massive uncontrolled flying metal" thing happening, and someone (likely you) getting hurt.

However, I also have looked at those weights and thought they would be useful linked to one of my diesel engines somehow. It's not like old, rusty bailers are hard to find around here. 

[Stan]

I was also going to say watch out for that baler flywheel.  I've worked many many hours standing on stookers and sitting on tractors watching baler flywheels go round and round and round and round (but I digress) and they don't look like precision castings to me! 
be very careful, very very careful !
Stan

[rcavictim]

Fellows, regarding the soundness of my bailer flywheel.  Physical inspection shows absolutely no casting flaws.  This baby is apparently made very nicely and I assume of good iron.  It has been turned on a large lathe at the factory on the outer portion and has a balance hole drilled in the side of the outer rim in one spot.  Where it is unmachined casting as in the central plate area it is superb quality.  In addition to this when on a shaft suspended it rings clear like a bell.  Sitting on OD on the concrete floor it still rings, although subdued.  I just completely sandblasted it on Thursday to clean off the old paint and a bit of minor surface rust so I can see a very even consistency in the color of the iron.  It is a nice uniform grey silver. There are NO PITS period. No surface casting voids hidden with plaster or bondo. The quality in this is clearly better than most Indian flywheels people routinely run on faith and get away with it. On the machined surfaces of the center hole and mounting surfaces the metal is as good as cold rolled steel in finish.  No micxropitting to be seen.  This is a VERY GOOD CASTING IMO. As I understand it the 60 MPH Rim Speed Rule gives a sufficient safety factor margin to accomodate whatever factors are involved in practical wheels.

In addition to apparent perfection it is probably 40 years old, so it has been age annealing, relieving a bit of the stresses that are unavoidable in a large casting.  I know that cast iron engine blocks with at least 100,000 miles on them are preferred by racing engine builders for the reason of the casting being `seasoned` and better as a result.  They result in a dimensionally more stable entity once machined to very tight tolerances.

Can someone give me an engineering based reason why this wheel is not to be trusted?

[Doug]

"Can someone give me an engineering based reason why this wheel is not to be trusted?"

Envy, we all want to spoil it for you so you give up and one of use can snap up your wheel in some sort of sneaky side deal.

This will give you some ideas, swap globe with fly wheel
http://www.youtube.com/watch?v=IJOuoyoMhj8&mode=related&search=

MUh HA HA HA....

[okiezeke]

Just hope it wasnt designed by an engineer.  They want to produce the cheapest, weakest product that can just get by in use.  Pick it up and double the stresses, and who knows.  Could run fine forever, but it only has to kill you once.  Guess I just dont trust engineers.
Zeke

p.s. Now a rail car wheel, there would be a good flywheel.

[Doug]

No, looked at that can't find a way to bush it, hole is too big to fit a standard SK bushing....

The ones I looked at were not ballanced.

Doug

[rcavictim]

p.s. Now a rail car wheel, there would be a good flywheel.
Zeke

I agree, fantastically strong quality steel, not cast iron.  Trouble is, to obtain one you would have to deal with the bogie man.   

[Doug]

No, I have to ask for one, but as I said the hole is too big for bushing.

Better to find some 1 inch or larger plate and have a disk cut

[ZackaryMac]

Rail car wheel...interesting. How much would one of those weigh? Besides a LOT!? 

[rcavictim]

No, I have to ask for one, but as I said the hole is too big for bushing.

Better to find some 1 inch or larger plate and have a disk cut

Doug,

WHO are you talking to?  Your last two posts seem like one half of a conversation in which the other half does not appear in this thread.