The Wankel engine seems to pop up in surprising places every so often, only to disappear into the ether before someone ultimately resurrects it for a new application and swears to get it right this time. Ultimately they come across the same problems that other Wankels suffered from, namely poor fuel efficiency and issues with reliability. They do have a surprising power-to-weight ratio and a low parts count, though, which is why people keep returning to this well, although this time it seems like most of the problems might have been solved simply by turning the entire design inside out.
A traditional Wankel engine has a triangular-shaped rotor that rotates around a central shaft inside an oval-shaped housing. This creates three chambers which continually revolve around inside the engine as the rotor spins. The seals that separate the chambers are notoriously difficult to lubricate and maintain. Instead of using a rotor inside of a chamber, this design called the X-Engine essentially uses a chamber inside of a rotor, meaning that the combustion chamber and the seals stay in fixed locations instead of spinning around. This allows for much better lubrication of the engine and also much higher efficiency. By flipping the design on its head it is able to maintain a low moving parts count, high compression ratio, and small power-to-weight ratio all while improving reliability and performance and adding the ability to directly inject fuel rather than rely on carburetion or other less-ideal methods of fuel delivery that other Wankels require.
Astute internal combustion aficionados will note that this engine is still of a two-stroke design, and thus not likely to fully eliminate the emissions problems with Wankels in a way that is satisfactory to regulators of passenger vehicles. Instead, the company is focusing on military, commercial, and aerospace applications where weight is a key driver of design. We’ve seen time and time again how the Wankel fails to live up to its promises though, and we hope that finally someone has cracked the code on one that solves its key issues.
While there are plenty of places around the world to get a great cup of tea, no one has quite burned it into their culture like those in the United Kingdom. While they don’t have the climate to grow the plants themselves, they at least have figured out the art of heating water extremely rapidly in purpose-built electric kettles while the rest of us wait to heat water on our stoves and microwaves. But that’s still not fast enough for some, like [Finlay Shellard], who just completed this jet-powered tea kettle.
[Finlay] took some inspiration cues and parts from another jet engine he had on hand that was powering his toaster. This is a pulse jet design, which is welded together from laser-cut pieces of sheet metal with guides welded in place to allow water to flow around the combustion chamber and exhaust. Pressurized water sits in a reservoir at the top of the engine, and when it is up to temperature, a valve allows it to flow to the engine to heat up. When it has passed the jet engine section, it passes a tea bag holder and then out of a spout at the end of the engine.
A few tests at 100 PSI had the hot tea exiting the engine in a non-linear fashion, so the pressure was reduced. The device now makes tea at incredibly fast speeds, with the only downsides being access to some sort of jet fuel, and also the need for a protective hearing device of some sort. For anyone attempting to do this themselves, take a look at this build which includes a turbocharger design for improved efficiency of the pulse jet itself.
Anyone who grew up during the Cold War will remember the rhetoric of the era with respect to technology. To paraphrase a little, our planes or rockets were based on the finest and latest high technology, we were told, while theirs were held together with string and sealing wax from the 1940s. This neglected the fairly obvious fact that Soviet probes were visiting all the planets, something they must have had some pretty good tech at their disposal to achieve. This was then explained as the product of their having stolen all our super-advanced Western tech, something we now know that our lot weren’t averse to either when the opportunity arose.
It’s this which is brought to mind by the mirth of the Western commentators at the Afghan car’s supposedly humble engine. It doesn’t matter what you think of the Afghan regime (and there’s plenty there to criticize), the car should be assessed on its merits. After all, it’s hardly as though the engine in question didn’t find its way into more than one sports car that Western commentators might find appealing.
If you grew up before high gas prices and strict emission control regulations, you probably had — or wanted — a car with a V8 engine. An engineering masterpiece created in France, it would define automotive power for the best part of a century. Of course, you can still get them, but the realities of our day make them a luxury. [Vlad] shows us his latest Christmas list addition: a fully-functioning but tiny V8 — the Toyan FS-V800 that has a displacement of two centiliters.
It runs on R/C nitro fuel and is claimed to be the world’s smallest production V8. You can buy the thing built or as a kit and we suggest to protect your street cred, you claim you bought the kit even if you go for the assembled version. The cylinder bores are 17 mm and 16 tiny valves regulate the flow. There are even tiny mufflers for the manifold exhaust. [Dennis] has a video of his operating that you can see below, and his YouTube channel has a lot of information on building the kit and some modifications, too.
Cooling? Water-cooled, of course. The manufacturer claims the engine can rev to 12,500 RPM and can produce over four horsepower. The total size would allow it to fit easily in a five inch cubical volume. You could build it into something, or just display it as a conversation piece. Be prepared for sticker shock, though. We hear the going price for these is about $1,500.
For an engine that has a retail price of just $160 USD, we’ve got to admit, the inside of the Predator doesn’t look too shabby. Admittedly, [HowToLou] determined that the cause of the failure was a blown connecting rod, but he also mentions that somebody had previously removed the engine’s governor, allowing it to rev up far beyond the nominal maximum of 3,600 RPM. No word on who snuck in there and yanked the governor out, but we’re betting it wasn’t the 7-year old driver…
Replacing the connecting rod meant taking most of the engine apart, but for our education, [HowToLou] decided to take it a bit further and remove everything from the engine. After stripping it down to the block, he re-installs each piece while explaining its function. If you’ve ever wanted to see what makes one of these little engines tick, or perhaps you’ve got a Predator 212 cc in need of a repair or rebuild, the presentation is a fantastic resource.
It is no secret that we like simulating circuits before we build something and there are plenty of great tools for that. But what about those of us who work on cars? Well, you might try engine-sim which is a real-time internal combustion engine simulation. Honestly, the program freely admits that it isn’t accurate enough to do engineering or engine tuning. But on the plus side, it has audio output and is at least good as an educational tool to show an engine running and how different parameters might affect it. You can see a video of the tool below.
[Ange-Yaghi] mentions that the code was primarily to power the YoutTube demo. However, the Readme hints that it might be better — or at least different — and collaboration to make it better is welcome.
The first video from [3DPrintedLife] attempting to make a liquid piston engine was… well… the operative word is attempting. The latest video, though, which you can see below gets it right, at least eventually.. He has a good explanation of the changes that made the design better. Turns out, one change that made a difference was to turn a key part of the engine inside out. You can see the video below.
The first version would quickly break during operation and while the first new version didn’t work very well, it did stay in one piece which is a definite improvement.