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“Inside-out Wankel” rotary engine delivers 5X the power of a diesel

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111–120 of 211 posts

Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#111

I know this is targeted towards military/aviation applications (now, initially it was different), but, I honestly cannot understand why there is so little research on just making a hyper-efficient low-maintenance engine that runs at maybe 2 optimal rpms and powers a small battery bank plus electric motor (i.e.. typically series hybrid). None of these gas engines will come anywhere near the power-per-pound & torque ou…

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Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#112

I know this is targeted towards military/aviation applications (now, initially it was different), but, I honestly cannot understand why there is so little research on just making a hyper-efficient low-maintenance engine that runs at maybe 2 optimal rpms and powers a small battery bank plus electric motor (i.e.. typically series hybrid). None of these gas engines will come anywhere near the power-per-pound & torque ou…

Are you aware you are essentially describing the original Toyota Prius? the engine is optimised for constant low rpm/low torque/high efficiency, whilest relying on the battery/electric motor for torque and temporary extra power

Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#113
post #78

Kind of weird article that doesn't talk about either the main benefits or design hurdles. The advantage of the LiquidPiston design is that at the time of ignition, the combustion chamber is a roughly round shape, as opposed to a traditional rotary where it's a long crescent. This should theoretically improve the emissions and fuel economy to be more like piston engines. I don't think Liquid Piston was talking about a…

All the numbers in the article were really small and seemed to aim at use cases that are all about small and reliable. Is anything stopping this from being scaled-up to be a light but very powerful engine for a sports or supercar? This could be a huge innovation in racing if it scaled.

Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#114
Surely, I can't be alone in reading this having driven an RX-7, numerous turbos, but no diesels, thinking this is EXACTLY what I need to replace the 310cc single cylinder in my BMW motorcycle that gets 70 MPG consistently, sits comfortably at 70 MPH on the highway, but is slow on the uptake in a crowded on-ramp. I remember the BMW single being a revelation because it's a single, DOHC, eats corn gas for breakfast without indigestion and has plenty of breathing room at the top end of the tach, which is unusual in single cylinders at redline, 10.5K RPM IIRC. One can only hope since one has less-than-zero mechanical engineering skills.

Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#115
post #112

I know this is targeted towards military/aviation applications (now, initially it was different), but, I honestly cannot understand why there is so little research on just making a hyper-efficient low-maintenance engine that runs at maybe 2 optimal rpms and powers a small battery bank plus electric motor (i.e.. typically series hybrid). None of these gas engines will come anywhere near the power-per-pound & torque ou…

Are you aware you are essentially describing the original Toyota Prius? the engine is optimised for constant low rpm/low torque/high efficiency, whilest relying on the battery/electric motor for torque and temporary extra power

Actually it just keeps the engine at/close to minimal brake-specific fuel consumption:

https://en.m.wikipedia.org/wiki/Brake-specific_fuel_consumpt...

Which covers a range of RPMs.

Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#116
looks neat and I am in no way any kind of expert; I wonder why there is an external counterweight? It seems to me that the rotating 'piston' has hollow chambers in one side only to allow passage of gases and therefore needs a counterweight to balance it; is there a reason they cannot have some hollows in the other side but not have them connected to the burn chamber so that the piston is balanced by design, and the external weight not required?

Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#117
post #89
post #78

Kind of weird article that doesn't talk about either the main benefits or design hurdles. The advantage of the LiquidPiston design is that at the time of ignition, the combustion chamber is a roughly round shape, as opposed to a traditional rotary where it's a long crescent. This should theoretically improve the emissions and fuel economy to be more like piston engines. I don't think Liquid Piston was talking about a…

The four strokes of a four stroke cylinder are intake, compression, combustion, and exhaust. That's down, up, down, up. Since there's no down or up in any of this engine's combustion chambers, "strokes" is probably inappropriate.

The strokes have nothing to do with up and down (e.g. flat motors, like a boxer), but to do with compression and expansion. The direction of compression doesn't really matter aside from packaging concerns.

As you said, 4 stroke has intake, compression, combustion, and exhaust. That's expansion, compression, expansion, compression. It fires between compression and combustion.

A 2 stroke motor has compression and expansion. It fires between compression and expansion. Intake, exhaust, and combustion happen during the expansion phase.

A rotary motor is traditionally 4 stroke, and I'm not sure a 2 stroke version is feasible. The LiquidPiston rotary appears to be a 4 stroke to me, despite the article text.

Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#119

Sounds like it could be awesome for some GA applications given the lack of weight budget and it seems like they did solve the issues with rotaries. Hopefully someone starts cramming them in some experimentals!

General aviation are perhaps the most cautious and wary ICE users around. Most of the engines used in GA, Lycomings and Continentals, are essentially 1960s designs with very well known cost, performance and reliability characteristics.

That is not to say change is impossible, GA's overdue changeover to unleaded gasoline seems like an inevitability. Unleaded gas is already being approved for many of these engines, like new production O-360 engines (which date back to the 1950s.)

Re: “Inside-out Wankel” rotary engine delivers 5X the power of a diesel

#120

A non-turbo diesel is an interesting choice of competitor. The big selling point of the Kohler motor is that it's almost silent - even the valve train is belt-driven to reduce noise. Not sure a rotary engine screaming at 6500RPM is comparable here to a diesel with a peak torque at 2000 and peak power at 3600. > LiquidPiston has been working on these X-engines for nearly 20 years now, I'm guessing they will never actu…

If it's truly a 5x size reduction, then there's still plenty of room for sound dampening materials!
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