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Comment by 0xFFFE | Hacker News Reader

Wankel Engines are not new. May be these engines have better lifespan.

The posted article and also the "how it works"[1] make it very clear and specific that this is _not_ a Wankel, and details the differences.

[1] https://www.liquidpiston.com/how-it-works

Sure, their engine and they can claim whatever they want.But I have the right to disagree. V4,v6,v8, inline twin, inline 4, 2-stroke, 4-stroke they all have different torque,power curves and characteristics, and there is big difference between Petrol/Gasoline and Diesel engines as well. BUT, they all are considered as internal combustion engines that convert translational motion into rotary motion.

No, you don't really have the "right to disagree". This is clearly not a Wankel engine. In a Wankel engine, the rotor is approximately Reuleaux triangle-shaped. In this engine, the rotor is pill-shaped (obround). Yes, it is a rotary engine and it is an internal combustion engine, but it is not Wankel.

Oh really? this is fun, I absolutely have the "right to disagree". Even with your comment. You can claim that this engine is built by the Martians, nobody is stopping you. You have the same "right to claim" whatever you want.

This isn't a subjective issue. A Wankel engine is a certain type of engine with certain key characteristics, by definition. The LiquidPiston engine does not share all of these key characteristics, so it is not a Wankel engine. Of course you can call whatever you want a Wankel engine, nobody can stop you. You can call the SpaceX Raptor engine a Wankel engine. But we will ignore you, because you are objectively wrong.

See? this comment is an improvement over your previous ludicrous comment of "No, you don't really have the right to disagree". Keep working on it. Meanwhile, read this. https://news.mit.edu/2014/liquidpiston-small-efficient-rotar... Especially, this part. "The X Mini is essentially an upgrade in design and efficiency of the compact Wankel rotary engine, invented in the 1950s and used today in sports cars, boats, and some aircraft."

Yes, I see how the article literally says this is not a Wankel, but rather an "inverse Wankel". Taking many of the main ideas behind another engine and using those ideas to make your own (with different key features) does not make it the same engine.

My saying you don't have the "right to disagree" was a response to your ludicrous assertion that an engine can be whatever you want it to be, not what it is. Any ludicrousness coming from that is purely a function of how ridiculous your original response was.

They are keen to claim that it's not a wankel engine.

The rotor in the center of the LiquidMotion device is shaped more like an oval (or race track) while the Wankel rotor is shaped like a bowed-out triangle. The LiquidMotion rotor has volume within that is carries gases, while the Wankel rotor is solid (or at least if it's hollow the volume inside isn't used). I don't recall ever seeing a counterweight on a Wankel but then I'm not even a little acquainted with Wankels in the field so it could be that Mazda forgot to tell me.

There is of course the possibility that this is a Wankel as far as patents would say. As different from a Wankel as a true Hemi is from a regular V8.

Someone above posted https://uploads-ssl.webflow.com/5f6086e9bbbabd41a20f2984/5f6... which gave me a much clearer sense of how this is an "inside-out" Wankel.

There's nothing inside-out about that design. They've just moved the location of the exhaust/intake porting. It's a neat reconfiguration idea, but it's still a Wankel engine.

Instead of a triangular piston in an oval chamber it's an oval piston in a triangular chamber. Seems pretty inside out to me.

Yep. Instead of the seals on the rotor, the seals are on the chamber (much better cooling and lubing opportunities). Instead of the intake/exhaust ports in the chamber, the intake/exhaust goes through the rotor (at first...)

The Mazda RX-8 uses a counterweight. (Actually, on the manual-transmission version it's a flywheel that has a sort of lip around the rim that's thicker on one side than the other.)

Aftermarket flywheels are generally symmetrical, with a way of bolting on a separate counterweight piece.

(The reason I know this is that I'm working on converting an RX-8 to electric. I got the car cheap with a messed-up engine, and I bought an aftermarket flywheel to replace the lopsided stock one because I don't want the car to shake itself to pieces. I haven't gotten around to ordering the adapter plate yet, but CanEV makes an RX7/8 transmission adapter plate along with two different versions of a coupler that attaches the motor to either a tapered-shaft style flywheel, which is what the car had originally, or a six-bolt variant for some other version of the engine.)

Yeah, but it basically is. The most important difference, as it appears, is they've ported the intake and exhaust through the piston rather than through the block. I don't quite understand the claim that it has a different thermodynamic cycle...

Here is their diagram[1] of the cycle. Wankel engine uses the otto cycle (blue), theirs is what they are calling the High Efficiency Hybrid Cycle, or HEHC (in red). In terms of shape they do seem approx. the same, so when LiquidPiston says theirs is different I think they are just saying it is a more efficient cycle, not fundamentally different in terms of stages.

[1] https://uploads-ssl.webflow.com/5f6086e9bbbabd41a20f2984/5f7...

Thanks, that is quite obviously the identical thermodynamic cycle between the two engines.

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