Letmo 0,6 cc Replica Model Diesel Engine

Design History: The Letmo engine was originally designed and manufactured in Czechoslovakia in 1949 to 1950 by Josef Pfeffer in Brno. This replica engine is made and distributed by MP Jet Engines in about 2002.  

Design Features:
Rear induction;
side port;
plain bronze main bearing;
admission is by induction of the skirt of the piston and thus the direction of rotation is unimportant.


Specifications:
displacement, 0.6 cc  (0.0366 cu. In.);
bore, 8 mm diameter. (0.315 in.);
stroke, 12 mm. (0.472 in.)

Observations visual material by YouTube Channel valic000:

Here we have a replica of a well known Letmo 2,5 diesel made by the famous Czech model engine designer Josef Pfeffer. He made so many lovely and quality engines in the past in my home country. I can only say about MP Jet engine...very well made and with perfect finish and fits. I got a filled in guarantee card when I bought some years ago a 2,5 cc diesel from E-bay and that was a very nice runner. I must quit collecting as, I have all ready too many engines at this moment.... but this one was not expensive and free shipping and with extra tank and also prop...so I give myself a "green light"... for just this one last time....somewhere I will find a small space for him. I can highly recommend MP jet diesels. Great engines! Thanks for watching.

 

Extremely Rare Spanish Byra 1 cc Diesel

Special thanks to Peter Valicek (YouTube Channel valic000) for uploading this content.

 The first Byra was a side-port 5 cc .

Introduction:
The power full ZOM, and Llam engines are better known or also the competition engines from the Parres brothers.All very good performers! This little Byra engine I get some time ago,as the parts were present,but it was impossible to make it run because of the fits. There is not a lot known of the 1 cc version.About the others,special the 1.5cc and 2.5 cc bb versions is far more known,as there were also tested by the British modelling press. Its even possible,that the 1 cc make it only thru the prototype fase. The idea was,to have a counter part of the ED bee,which was a huge success sale not only in Britain,but all over Europe. There are no sale records of the Byra 1 cc.Strange enough were the boxes also all ready made. What my friend Jesus told me,the Byra 1 cc were poor performers and will be never a sale success, I do my best, to give the engine good fits and I think,with a 7x4 prop it will not really perform badly. How ever,its a cheap concept design,with the most interesting part the cooling head,with a semi bore cut out of it, to get the venturi drilled out. Why not put the venturi a bit further to the front? Well, that answer could only come Mr. Battlo himself could answer. He had enough know how to build engines. He was also a good speed and stunt flyer. In the Aero modeler there is a lovely plan of the Spanish build ME 109, maybe worth to give it a try to build? So I hope you like this clip of another rare model diesel engine. It was a big job, as always with some setbacks but that's worth it. And a big, big muchas graciac for Jesus Ortega Delgado. His help is priceless!!

 Circa 1954 the 1 cc appeared for the first time.
Possibly there are fewer than 10 of these little gems left if the world today.

 Right side view

 Rear 3/4 view

 Left side view

 Specifications:square volumetric design (bore and stroke both 11 millimeters); weight 69 grams.clockwise runner. 

 Parts to be fabricated to make her a runner are: a new crankshaft, matching cylinder and piston.

 Also two transfer channels need to be milled out in the crank case.

 The first task is to replicate the original cylinder liner.

 Sketch of the cylinder and porting. shown above and below.

 Cutting the ports.

 It was decided to make the boost ports at plus and minus 45 degrees from the center-line in an effort to improve scavenging..

 completed cylinders with their ports are shown above.

 A new shaft is made slightly larger to produce a better fit in the crank case, also the big end is firtted with a bronze bearing to improve ware characteristics.

 The new shaft is made with an integral balance weight to produce a smoother running longer lasting engine

 Finished parts ready for assembly.

 Finished engine ready for a test run

 Standard Byra 1 cc crankcase has a slot at the front for some unknown reason, possibly to facilitate drilling of the intake venturi.