Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

newatlas.com

Post reply on HN
Print view View original

31–40 of 211 posts

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

#31

Post by vvillena »

skullone wrote: post #7
djaychela wrote: post #5

Earlier quoted context omitted.

They also have issues meeting emissions targets - both because of the basic design (there isn't the ability to actively control valve timing events), and also because they typically need some sort of lubrication for the combustion chamber. They are similar to two-stroke engines in these respects.

Running them at a pre-determined RPM constantly can resolve lack of VVT, but that limits their applications. New materials for apex seals being researched could alleviate their longevity issues too. But, I have a big soft spot for rotaries and would love to see them applied more :(

Isn't this how the range extender in the MX-30 works?

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

#32

Post by KAMSPioneer »

Cockbrand wrote: post #23

Surely the engineers who came up with this are a lot smarter than myself, but to me it looks like the lower half of the rotor rotates into the combustion and thus has to work _against_ its force. If this is true, I'd assume that this takes away a lot of effectiveness.

I'm not sure what you mean -- are you referring to at the end of the combustion cycle during the exhaust phase? If so, then because the exhaust channel is open, the gases in the combustion chamber won't be exerting appreciable force on the shaft/rotor, the gasses will simply escape through the exhaust channel. At least, that's how I see it.

But maybe I've understood you wrong.

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

#33

Post by Zak »

mywittyname wrote: post #10

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…

The specific version described in the article appears to be a Diesel rotary that runs on jet fuel with military UAVs as a primary application.

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

#34

Post by manarth »

djaychela wrote: post #5
debacle wrote: post #3

My understanding is that everyone acknowledges that rotary engines are great, bt in comparison to piston based engines they have far shorter longevity.

They also have issues meeting emissions targets - both because of the basic design (there isn't the ability to actively control valve timing events), and also because they typically need some sort of lubrication for the combustion chamber. They are similar to two-stroke engines in these respects.

Whilst also being worse-performing?

Take a two-stroke Moster 185 engine: 25 HP at 7.800 RPM, for a 15kg package.

I'd be keen to understand how (if) this outperforms a typical two-stroke.

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

#36

Post by bmelton »

andy_ppp wrote: post #22

I'm surprised the air intake isn't more aerodynamic, more like a fan blade to compress the air into the engine? Could this engine be fitted inside the rear wheel to save space and weight as well?

That's a really good idea.

Mazda is doing something that I think is fairly novel, which is almost exactly what you've described. They've scaled down the rotary engine from their RX cars to a single-rotor and put it into their new EV (almost tucked into the front wheel well,) and letting it act as a 70ish horsepower generator for the otherwise battery-powered car to extend range.

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

#37

Post by Syonyk »

causi wrote: post #14

Ok, so they're "shooting for" a performance of 1hp per 1.57 lbs of engine weight. A Toyota Camry engine produces 1hp for every 1.41 lbs of engine weight. It produces 1ft-lb of torque for every 1.94 pounds of engine weight, compared to 1.58 for the Camry. How is this revolutionary motor being outdone by a mid-range sedan engine?

> How is this revolutionary motor being outdone by a mid-range sedan engine?

Go ask your Camry engine to make 100% rated power indefinitely, and see how long it holds up. That's the difference.

A typical car engine is designed to make 30-50hp sustained, and occasionally generate more power for reasonably short periods of time.

An aviation engine, generator engine, or any sort of "industrial" engine is going to be able to sit there, making full rated horsepower, for thousands of hours without any trouble at all.

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

#38

Post by causi »

Syonyk wrote: post #37
causi wrote: post #14

Ok, so they're "shooting for" a performance of 1hp per 1.57 lbs of engine weight. A Toyota Camry engine produces 1hp for every 1.41 lbs of engine weight. It produces 1ft-lb of torque for every 1.94 pounds of engine weight, compared to 1.58 for the Camry. How is this revolutionary motor being outdone by a mid-range sedan engine?

> How is this revolutionary motor being outdone by a mid-range sedan engine? Go ask your Camry engine to make 100% rated power indefinitely, and see how long it holds up. That's the difference. A typical car engine is designed to make 30-50hp sustained, and occasionally generate more power for reasonably short periods of time. An aviation engine, generator engine, or any sort of "industrial" engine is going to be abl…

going to be able to sit there, making full rated horsepower, for thousands of hours without any trouble at all.

The XTS-210 can do that?

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

#40

Post by projct »

Gordonjcp wrote: post #9
debacle wrote: post #3

My understanding is that everyone acknowledges that rotary engines are great, bt in comparison to piston based engines they have far shorter longevity.

They're not great, at all. They have very few moving parts and they are very smooth because there are no reciprocating parts. Other than that, they have emissions like 2-stroke engines because of the incomplete combustion and we have never been able to devise any kind of material to make the apex and side seals last anything like as long as piston rings. Piston engines are a terrible way to power vehicles, but everyt…

LiquidPiston addressed both of those issues.
Post reply on HN