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

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

#161

Post by DesiLurker »

driverdan wrote: post #110
DesiLurker wrote: post #107

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…

One of the reasons is government regulation. I'll talk about US regulation but similar situations exist in other countries. 1. US incentives and regulation result in car manufacturers having to shift production from hybrids to EVs. 2. In order to qualify as an EV a vehicle can't have a range extending ICE that provides more than a 50% range increase. There's also a very low limit to the size of the fuel tank. These r…

US incentives aside, Nothing was stopping them from doing this for more expensive vehicles even if they didn't care about environment. I mean wouldn't you want to have a pickup truck with acceleration & torque of an EV with 2+1 motors powered by series hybrid and also have fuel economy of a 40mpg in city?

I think its just institutional laziness & innovators dilemma. Even in last 5 years when it was clear Tesla is starting to rise they decided to sit on their hands and do nothing. Even till last year toyota has been singing BS about hydrogen cars and not enough lithium. they deserve whats coming to them.

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

#162

Post by digdugdirk »

coryrc wrote: post #92
digdugdirk wrote: post #44

Earlier quoted context omitted.

Mazda really seems like the only company innovating in the ICE space (this, wankel rotary engines, skyactive engines) and their cars look damn good these days too. On top of that, they make fun cars. With buttons and knobs on the dash! I'm glad they're still around doing their thing.

Wankel is noticeably worse in about every metric, especially pollution and lifetime, so I wouldn't be too excited about it.

Agreed. I feel the same way about every programming language beyond assembly. I mean, what's the point of trying something new and different if it isn't immediately better than the competition in every possible metric?

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

#163

Post by MichaelZuo »

DesiLurker wrote: post #156
tda wrote: post #112

Earlier quoted context omitted.

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

yes I am well aware of Prius series configuration but it is still a regular engine shrunk down and fine tuned. What I am asking for is something very ground up redesigned for maximizing one thing only efficiency of energy conversion. couple of examples of this are Aquarius engines or [1]. basically you cut out all the unnecessary stuff and all the maintenance/repair plus cost with it. Current engines are complex beca…

And how will the tens of billions in R&D cost, reconfiguring the supply chain, service network investments, etc., be amortized?

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

#164

Post by m463 »

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?

For the camry, is that just the motor? Does it require support, like say the cooling system?

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

#165

Post by pengaru »

m463 wrote: post #152
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…

btw: I had a mazda rotary engine car, and the 7000rpm shown on the tach seemed exciting compared to a piston engine... except it wasn't really true. It really ran at 1/3 that speed.

There's only a grain of truth to what you're saying here.

The eccentric shaft does indeed spin at the indicated RPM, just as a crankshaft on a piston motor does.

It's just the rotors move at 1/3rd the eccentric shaft's rate, which is a design feature enabling substantially higher than 7000RPM with little effort.

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

#166

Post by Supermancho »

nogridbag wrote: post #93
mywittyname wrote: post #17

Earlier quoted context omitted.

More antic-data: i worked with a guy whose brand new RX-8 needed two engines in the time we worked together. Granted, his was a 04 automatic, which is the worst combo. But still, Mazda didn't go out of their way to extend the engine warranties on the early RX-8s for no reason. Did you happen to have an 08+ model with the updated engine and/or remove teh catalytic converter?

My RX-8 needed a new engine at 50k miles. As you likely know, if you start and stop an RX-8 engine without allowing it to warmup you risk flooding the engine. In my case, I was taking a trip with my family and my RX-8 was blocking the driveway. We were running late for the flight, so I pulled it out, parked it back in the driveway, and let it idle there for 30 seconds knowing I'm not supposed to shut it down so quick…

I also experienced this flooding issue. Running it to a high rpm before shutoff to avoid the flooding, was a convenient workaround.

Why flooding the car (or frankly doing anything to my RX-8's engine) would require it to be replaced seems ridiculous. The casing of the engine is a solid piece of steel. Removing the ring gears and shaft (which you have to do for cleaning every 100k mi anyway), there's nothing to break.

Ofc, if you introduce the engine to some exotic combustion or get some foreign material in there, you could scar any part of the casing and that would brick the engine.

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

#167

Post by pengaru »

This motor is doomed... dirty exhaust gases exiting through part of the rotor? Only a matter of time before carbon+sludge builds up and the thing is out of balance.

This is one of those designs that works fine initially when everything is fresh.

Diesel piston engines work fine when everything is worn out and full of goo.

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

#168

Post by davidbanham »

kortex wrote: post #98
davidbanham wrote: post #60

A commodity chainsaw (Stihl ms660) returns 1.4kg per kw from 2 stroke fuel. Before any performance tuning takes place. That’s at about a quarter of the size of this. I bet there’s efficiencies to be had if it were scaled up. I’m just not sure this is the game changing breakthrough the article’s tone suggests.

Two-strokes are extremely dirty, due to blow-through of the fuel-oil mixture, incomplete/less efficient combustion due to crude fuel metering, and inability to use conventional catalytic converters (due to fouling from the above two points). But they do afford roughly double the power-per-RPM of four-stroke engines, and a further power-to-weight multiplier due to their simpler design. AFAIK there's nothing mechanical…

The rotary in the article is a 2 stroke design, by my understanding.

Fuel injected 2 strokes have been around for years now. In saws, the Stihl 500i.

Scaled 2 stroke engines, both with and without fuel injection, have also been around some time. The KTM 300 XC is a very modern example with 300cc displacement, so the same general category as the one in the article. Modern outboards on boats go even bigger.

Yes there’s a push on at the moment to retire the fleet of small 2 stroke engines in older garden power tools. Emissions controls have been tightening up on new tools over the years. Electric tools are rapidly displacing them with lower maintenance requirements and less noise.

There’s a lot more to 2 stroke engine development than just saws and lawnmowers from the 80s, though.

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

#169

Post by davidbanham »

pengaru wrote: post #167

This motor is doomed... dirty exhaust gases exiting through part of the rotor? Only a matter of time before carbon+sludge builds up and the thing is out of balance. This is one of those designs that works fine initially when everything is fresh. Diesel piston engines work fine when everything is worn out and full of goo.

The exhaust gas recirculation valve on a modern diesel engine does exactly this. It diverts a portion of the exhaust product back into the intake manifold of the engine to achieve more complete combustion and lower emissions.

Yes, it does result in a buildup of goo in the intake. No, the engine does not run well in that state. That’s what maintenance is for. Clean out the goo every 50,000km or so and it’s fine.

Modern diesels are very reliable machines, just like modern petrol engines. They’re certainly not the robust rocks they used to be, though. High pressure common rail fuel systems, precision injectors and multi stage turbos are standard issue these days and they all require regular maintenance, clean air and clean fuel to operate properly.

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

#170

Post by davidbanham »

davidthewatson wrote: post #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 with…

People have shoehorned diesels and wankel rotaries into BMW airhead frames. It’s possible but not for the faint hearted.

With a small frame like yours you’d probably be better served by an EV conversion if you want to go down that path.

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