The RJ Customs Y200 Stirling Engine wasn't the first complete engine we've made. The first one came when we were looking into model engines 2 years ago and we discovered Stirling engines. We immediately fell in love with the idea of turning heat into mechanical energy so we set out to make one, and in two months we had our first proof of concept engine. The engine had aluminum top and bottom plates, but had a custom PVC cylinder we modified, and the displacer piston was Balsa wood we got from a craft store and cut. The engine worked and will run again if we want it to ( haven't fired it up in a long time) and this engine proved to us that we could manufacture a large ltd Stirling engine. That engine had a lot of things to improve on like the fact that the cylinders were oi-lite bushings, and the fact that the displacer would periodically fall off, but it did work. We then set out to make a much larger engine to put on the market which isn't shown in the picture but it looks very similar to the final engine. There was many challenges with building an engine of this size, one of which was how to heat such a large area with just two candles. The solution was the skirt on the bottom of the hot plate which allows the heated area to be thinner, but also trap gases to increase the efficiency of heat transfer. The legs on the engine are angled to also force the gases to the front of the engine to heat the plate evenly We also largely increased the size of the cooling tank to allow the engine to run more efficiently. This new engine was designed with greased/ sealed ball bearings because we knew the power capacity was there to deal with the extra drag of the bearings, and we wanted to never worry about the bearings wearing out. Another change from our original engine was the cylinders. We didn't like the fact that we had to oil our previous engine as this is ongoing maintenance for an engine, and it produced drag on the engine, so we wanted to make this new engine in a way that never needs oil, which was more interesting to do than it sounds. We managed to find a company that offered industrial bushings with graphite plugs that provide a dry lubricant to shafts during operation, so they never need oil. We were able to incorporate these into the engine, which made the entire engine free of oil. Even then we didn't stop, and we came to the right engine in the picture. We made many subtle changes in appearance and performance to this new engine such as a thicker mid plate to cool the engine better, more clearance top and bottom for the displacer piston inside the chamber, and an even larger cooling tank. There isn't a lot of visual difference between our second and third engine, but that is because many of the new parts were added to the 2nd engine for testing. This new engine was the strongest performing engine we've made, and is the model we are currently selling. Development of this engine was a big challenge because almost every component needed a matching fixture for machining. For the engine to be able to turn such a large mass (both flywheels and counterweights) it needed to have tight tolerances, and seal extremely well, because as the engine works off of pressures and vacuums, a leak would diminish performance. To overcome this, the bottom of the post that holds the flywheels is mounted with 2 O-rings and flathead screws to ensure the alignment is proper, and the O-rings ensure that there will be no leaks through the screws. The mid plate of the engine that houses the displacer chamber also has a visible orange O-ring to seal the chamber and prevent aluminum to aluminum contact between the hot plate and the mid so the heat doesn't transfer. This o ring is silicone, and it is a specialty for high heat applications. This particular silicone o ring can resist temperatures of up to 450 degrees Fahrenheit. The engine hot plate never reaches that heat, but we did this to make it so with regular operation the O-ring will never see anything close to it's limit. These O-rings are also put in the legs and candle arm of the engine to isolate the hot plate.  

Thank you for reading this article on the Y200 Stirling Engine's development, and stay tuned for more articles on this engine.


1 comment

Tom Curry

Fantastic engineering as a retired Toolmaker wish I could’ve been involved with the development of these great engine

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