Click on images to view larger picture.
Although only made in small batches, the engines produced in the Czech Republic by Josef Pfeffer have travelled far and wide. With small batches and wide dispersement, not even the most avid of Czech collectors have complete a set. So when this one was was shown to them, authorities on Czech engines, Jan Kafka and Jiri Linka, named it a "super collector's item", being one of a single batch of only ten engines that were made as an experiment by Mr Pfeffer in around 1961. The engine has a unique set of measurements as well; bore and stroke are 11.0 mm and 11.5 mm respectively, for an odd-ball displacement of 1.15 cc.
It has a ball bearing crankshaft—the front race is a tiny item, but it's there! The main journal diameter was constrained by the bore of the rear inner race, but Mr Pfeffer clearly intended this to be a high-performance engine and consequently went for a relatively large induction passage in the shaft despite the relatively small OD. This left very little metal holding the shaft together, and it is possible that shaft breakages were experienced whan the engines were tested. The rarity of the engine (this being the only known complete survivor) indicates that Pfeffer abandoned the design when he found that the shaft couldn't take it. Reducing the inlet passage diameter to increase the thickness of the shaft walls would reduce performance and unless it delivered a far above average performance, the cost and complexity of the engine couldn't be justified.