Motorboy

Yesterday i ran my homemade long stroke dieselengine. It is a 3.05 ccm volume, stroke 3/4", bore 9/16".
I tested the difference propeller, here are results:

12x6 4000 rpm
10x5 4500 rpm

The fuel mixture are same parts of ether, autodiesel and 10w40 motoroil.

It is not much difference at 500 rpm between bigger and smaller propeller for this engine.

What are you thinking about this engine with big torque?

Jens Eirik

knarF

Hey Jens

Nice work ! One day ill make these engines too .... (I hope) [sm=confused.gif]
Im trying to figure out how you mounted the crank in the 3-bit faceplate. (last picture)

Regards,

Frank

Motorboy

See at more pictures how to set the angle plate at 3 jaws chuck..

Jens Eirik

knarF

Thanks !

Got the picture. Still, is the faceplate fixed to the chuck with (just) one bolt ?
Probably not applicable to high rpm (inbalance)

Cherio !

Frank

AMB

Is this a rear intake and is that a bypass port on the front of the cylinder that was brazzed on??

Motorboy

Yes, all parts around cylinder are brazzed on, the cylinder was made of old wrist pin from car engine and the piston made of camshaft who has castiron.


Set low rpm about 200-250 rpm and take little cut each time. Use kerosene to smear the tool/aluminium and you get fine surface. Keep the tool sharp.[8D]

Jens Eirik

DarZeelon

Jens,


The numbers you are seeing are 0.05 HP at 4,000 RPM (12x6) and 0.03 HP at 4,500 RPM. This power decrease, as RPM is increased tells me this engine is timed for VERY low RPM; peaking around 3,000.

For the timing numbers of this engine, the 10x5 is over-speeding and in any case, these numbers are very far below the capability of a 3 cc Diesel engine.

I would expect an engine of this size to make at least 0.4 HP around 9-10,000 RPM.

The porting and fuel passages are not visible in any of the photos that you posted.
Piston ported intake and exhaust passages should have usable timing numbers, for this engine to actually make usable power.

The fact that it actually runs is an achievement in its own right, but the current available power may not even be sufficient for this engine, to lift its own weight.

JMP_blackfoot

Based on the performance achieved by typical engines of similar design in the 50's, 0.2 Hp would be a reasonable enough figure, but the RPM at which it is reached should definitely be higher, somewhere betwen 6,000 and 10,000.

AMB

Yoy might try a high pitch prop cut down to up the thrust that2 the prop speed of a RCV rotary 4 strk maybe a 9x12

Motorboy

Dar.. the engine are based at the construction from 1947 of the Battiwallah engine, but some of the parts are my own construction: improved piston (less parts, maked whole piston), cooling fins, crankshaft (to fasten propeller), backcover, carburator, exhaustpipe added.

Will the engine be useful for the airplane as oldtimer airplane to example?

Jens Eirik

DarZeelon

Jens,


I can now see the bypasses for the fuel/air mixture.

How is the induction of air/fuel mixture into the crankcase controlled?
I can see the crankshaft does not have a passage through it and the carburettor is obviously not on the front part of the crankcase.

From the drawings, I think it is a sub-piston induction.
The piston rises just enough to un-mask the passage from the carburettor (which I cannot see in your photos).

Could the induction period be very short, too short, not being sufficient to make enough usable power?

With the larger prop, or an even large one, it could get more power, enough to fly an 'old-timer' type model.

If you extend the carburettor passage to open earlier, you may be able to get more power from this engine.

Motorboy

Dar.. i has checked the induction perion in degree, measured 68 degree in induction perion. It can be too short time to take in mixture to crankcase.

I am thinking to increase timing to 90-95 degree in induction period when i am removing a bit of lower part of the piston.

And i maybe can drill a bit more in carburator from 1/8" to 3/16-4/16" to get more air and fuel mixture.

Exhaust period are at 135 degree. Transfer period are at 125 degree.

Induction are controlled of piston, also the sideported engine.

I used the method to measure the riming period showed as these photo..

Jens Eirik

DarZeelon

Jens,


I would not increase the carburettor passage too much.

Diesel model engines need a smaller carburettor, than their glow counterparts.


The MVVS 10.0 DFS/R uses the 7 mm #3216 carburettor, while the 10.0 GFS/R uses the 8 mm #3219 carburettor.

For a 3 cc engine, intended to peak at 10,000 RPM, you need about 1/3 the choke area of the 7 mm carburettor, or 4 mm, or 5/32" diameter. No more!

About the intake port, you may want to increase it even more. Glow engines' shaft and rotary valves are open for 190 degrees sometimes, but they are timed to be open mainly as the piston rises.

SGC

Jens,
In the drawings you posted the induction port is sloted wereas yours looks to be round . this could be the problem .
Stewart

Motorboy

No..
The carb. holder (manifold) are hole in outside, but inside inductionport are sloted. See at the drawning marked with red. The port area are larger than carb. hole area, it will not be problem. It is to late timing cause it will not run faster.

Jens Eirik

Hobbsy

My Feedback: (102)

MB, this Suevia has the same piston port induction as your engine, a round hole on the outside splaying out to a huge slot on the inside, I haven't run this engine yet but I think it is destined to become a Diesel. It is no lightweight so will only be suitable for a short nosed warplane or large Cub like model.

As to your engine, you have built yourself a real thumper that would be happy turning the main rotor of a Huey. I gather that it is a work in progress so are you going to keep tweaking it for more rpm. I happen to like torquey engines. They are just as profecient at pulling planes as high rpm ones. Well done.

SGC

Jens,
Just had a quick look at my mills75, its induction period is around the 90-95deg so the mod to your port timeing should improve it . The mills also has sub induction porting to , ie the piston skirt uncovers the exhaust into the crankcase.
Stewart
PS nice machine work on your motor and like Dar Zeelon says just building it and getting it to run is an acheivement.

Motorboy

Hi..
I has removed the part of lower in the piston and increased to 95 degree induction period.

I discovered there are a bit difference in starting of the dieselengine. But i has learned how to start easy in 1-2 flip of the propeller after priming.[8D]

The engine ran faster than early and the coolingfins feel warmer than before. Before i can hold the coolingfins, but not more, there are warm enough, but not to boilingpoint in water temperature.

I has measured the rpm and difference propeller. Here are the results:

6000 rpm 10x5 0.077 hp
5900 rpm 10x6 0.088 hp
4700 rpm 12x6 0.092 hp

Is it normal for a long stroke? I not know about the Battiwallah dieselengine ran faster than 6000 rpm[]

Jens Eirik

DarZeelon

Jens,


You are getting there.

Although my Prop Power calculator, based on the APC prop constant (1.1), calculates a slightly lower number, it is already 60% greater than what you were getting before.

The engine obviously peaks around 4,700 RPM, with a particularly marked drop from 5,900 to 6,000 RPM.
Try a larger prop (13x6?), just to see if there is still more power lower in the RPM band.

The transfer and exhaust ports are open slightly less, than similarly sized current engines that peak over 13,000 RPM.
I still think your deficit results from the bottom end, but I cannot be sure what.

Motorboy

Dar..
I searced the info about long stroke engine and revolution.

What i read about this long stroke engine are: "Of course, we all want to increase the power and torque of our engines :-) A longer stroke gives more torque, but a long stroke engine is a low-revving engine (there's a limit on how fast the piston can move in the bore. And a long stroke means that it takes longer from the one end of the stroke to the other. Which is half a revolution). Long stroke engines are also less efficient (as far as I know, relatively "square" engines "square" : bore = stroke) are the most efficient)."

And other: Long stroke piston enables large power on low speed

Also not a high rev dieselengine i maked??[]

I shall take test with bigger propeller than 12x6, maybe i has some 13 and 14 propeller, not sure which pitch at these propellers.

Jens Eirik

DarZeelon

Jens,


The 'long stroke' myth is long gone and forgotten...

An over-square engine (the more correct term for a short-stroke engine) can make just as much torque as an under-square engine.

The only difference is that a smaller diameter piston with a smaller ring, can have a decreased level of friction, but since the stroke is longer, this is also offset.

The ONLY real factor is cylinder filling, which at higher RPM, with the inertia of moving gas masses, can be higher (better Volumetric Efficiency).

I mentioned this in the 'Glow Engines' forum a couple of times, that it is no more than a 'buzz word'.
The F3A engine companies that made these 'long stroke' engines, have reverted to over-square engines...

Two under-square exceptions are the MVVS 10.0 cc (.61), that has a 24 mm stroke and a 23 mm bore and the MVVS 12.7 cc (.77), that has a 26 mm stroke and a 25 mm bore.
But the very high torque MVVS 15.0 cc (.91) is over-square, having the 12.7 cc's (.77's) 26 mm stroke and a larger, 27 mm bore.


Because of increased piston speeds, it is better for under-square engines to run at a lower RPM and because they usually also have smaller ports (or valves), they are often optimized to run at lower RPM, for a more complete cylinder filling.

David Owen

Here is a 1.5cc Battiwallah piston-port engine. Bore 11.4 x stroke 12.7-----certainly undersquare!
Ignore untested remarks.
David Owen

Motorboy

Dar..

I has checked these engines before 1950 years in the book "Engines for sportsmodels" wrote of Jiri Kalina,1983.

These engine made before 1950 ran not faster than maximal 7500 and lowest 4500 rpm. Mostly average between 4800 and 6000 rpm and developed average from 0.07 hp at 2 ccm engine to 0.24 hp at 6.1 ccm engine. Near all engines was long stroke engines and ran with big propeller.

After 1950 years these newer engines ran faster from 6000 to 10000 and until 14000 rpm as JMP_blackfoot wrote in early post as i am thinking are improved knowledge how to make better engines than before..

So i am thinking it is not wrong with the engine, it is engine constructor who has maked these engines before 1950 years with minimal knowledge about effective porting timing.

But thanks for all help as you has tried then i got improved the engine to run faster.

Jens Eirik

Motorboy

David..

Is this engine 1.5cc Battiwallah developed after 1950 years?

It is not so much as my engine in stroke : piston ratio.

My engine at 3.05 cc has stroke : diameter ratio at 1.33
Your engine at 1.5 cc has stroke : diameter ratio at 1.11

Also my engine are more undersquare than your engine.

1 are square engine, below 1 oversquare and above 1 undersquare.

Jens Eirik

DarZeelon

You're welcome, Jens.

Most of us here want to get more power out of our engines.
Some even understand the basics of how this is done.

So passing it to another interested member is the least we can do.


You can try taking the intake bypass and the exhaust timing on you 3.05 cc engine.
Maybe this can also be changed, to give more RPM, by 'raising' the sleeve, FE.

After all, you have already made some changes in the intake port timing, so the engine is not 'scale' any more.