Making a CYLINDER Head with NO Valves but ROTARY Ports!

The greatest channel of mini motors in the world.

The fact that you got it working that well considering how finicky these small engines are normally, that’s awesome.

In late 70's and early 80's with friends we tried different things how to improve compression in exactly the same system of rotating valve. We never managed to get more than 70% but mostly it was just around 60% of the theoretical compression. This problem was because surface of the valve and cylinder were not ideal to hold compression. At that time the tools we had were unable to offer absolutely smooth - mirror - surface and lubricating was problem as well. We used petrol mixed with oil which improved compression and reduced heath from friction. We designed 50cc motor but it proved too weak compared to ordinary scooter 50cc motor. However it was fun and we enjoyed it thoroughly. However my congratulation on your design and quite remarkable achievement.

You gotta love an engine that idles at 5,000 rpm! 👍

I think you need to make the valve openings a tiny bit larger in the post-open direction to solve the problem with throttle lag. Here is why: When you have a normal camshaft, when the cam lobe has passed the rocker, and the valve is now closing, there is a bit of "lag" from the point that the cam is no longer holding the valve open, and the valve physically closes. This because the springs need some time to actually close the valves when the cams allow the valves to be closed, since the cams do actually not PULL the valves closed by force. This "lag" is propably considered in the engine design, meaning the cams are a tad bit smaller than the duration you want the valves to be open, to compensate for the closing lag. I mean, theres a lot of mass that the closing spring of the valve needs to get accelerated to get the valve to close, its the valve itself and the rocker arm. And in a engine that makes 10k+ RPM, that acceleration adds up pretty much, meaning, for your rotating valve that actually have zero acceleration - its constantly rotating in the same speed as engine, you need to compensate for that acceleration, with larger valve openings. So I think you need to extend the valve openings slightly in the "forward direction", ergo make the valves to be open slightly longer than now, but still open the valves at the exact same time as now, just wait a tad bit longer before closing them, since what I have understand, you have designed the valve open time directly from the camshaft.

The sound of the work has become noble.

This is the type of content I have missed! I really enjoy watching JohnnyQ90 and 2STROKE STUFFING take a concept in their heads and try making it a working reality.

As my college senior project in IC Engines for mechanical engineering, my group designed this very thing except we had two cams, one for exhaust and one for intake. Both went through the center of the cam.

Been following this guy for years- he still manages to amaze me with his skills and insights.

Back in the 70’s I asked my mechanic/hot rodder dad what I could figure out to improve engines. He advised me to figure out how to do away with the valve train. It took me til the early 90’s and entirely in thought(a few toilet paper tubes for a visual representation), I came up with the exact same answer. Alas, not a machinist, but it is awesome to see it actually work. Bravo! You might think about reshaping the ports in the rotating rod to spiral on the shaft. If the shaft could then translate in and out of the head you could vary the port timing based on rpm.

Greetings from Texas! The rotary valve is not a new concept. I saw some research and a test engine more than 20yrs ago. The main problem they encountered was the heat dissipation problem for the rotary valve. The exhaust side gets very hot and expands where the intake side is cooled by the incoming fuel. This lead to sealing issues and exhaust leaks. Same thing happens if you separate the two and have separate intake and exhaust rotary valves. Great concept though. It liberates the issues concerned with standard tappet valves. Keep the content coming!

I agree. The idea and function of this design is amazing!

Great work! Been interested in rotary valve engines since reading an article about the Ilmor / Mercedes Formula 1 engine that used them (and got banned even before it raced, due to Renault complaining about it). Little tip: Machine your mating surfaces last. I must admit I cringed a bit when you put the rotary valve into the chuck to machine the inner surface... Also it looks like the sleeve inner surface is not as smooth at it could be, but I know it's hard to work at these small sizes. One other thing that makes engines difficult is thermal expansion rates of different materials (and with rotating parts you get different heat distribution through the part than through the static area around it), so keeping tight tolerance between surfaces without them binding / seizing is hard. When there is compression, the ports will be pressed against the sleeve, so I think the critical areas for leakage may be the ends of the valve more than the ports... maybe a simple pair of orings or labyrinth seals to help seal those will improve things with the existing design without having to machine any new parts (just cutting grooves to accommodate them in the existing ones)?

0:40 that was a great shot!

Wow, now that is a fantastic concept. This is a project that needs to be refined, definitely. Outstanding video!

Seriously, it's wonderful and inspiring to watch that being made.... The mind goes through dozens of prototypes and variations... Loved it. I also had in mind a chap who had built a larger, maybe 100cc? engine with the same type of rotary valve arrangement. He didn't have the precision you managed and lost most of his compression. Half the video was him making it, the other half was him trying to start it... These things are notoriously difficult to make gas tight without some clever thought. You did very well by making it so beautifully. So impressed.

You know you're a machinist when you're thinking about stepover and cutting speed while shaving.

never knew about rotary ports , incredibly interesting that the engine gained some top end , would be cool to see what kind of power & torque curve it gets on a dyno compared with the standard sohc ... i also wonder if having shallower/deeper / different exit angles on the rotary ports would affect compression & power?

I've been watching your channel for a while, and I've always enjoyed it. Im a cnc machinist by trade, and I run 5 axis mills. I love the mix of machining and small engines and even rc on your channel. This episode, though, by far my favorite. A little bit of everything with a cool concept that I've never seen before.

Can you make inline diesel model engine 🙂