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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

#131

Post by mmetzger »

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…

Long since mattering, but you could move them like this if you started it, rev'd it beyond 4k RPM, and then shut the motor off prior to it dropping below 4k. Basically, the idea was the rotors would force the fuel / oil mixture out of the crankcase and keep the spark plugs from fouling.

I loved my RX-8, but it was a pain in the rear. Switched to a WRX and got 50% better gas mileage, more power, more torque, and way more room. This of course bypassed the need to check / refill the oil every other fill up (aka, every 300-ish miles) all while trying desperately not to burn your hand.

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

#134

Post by mcronce »

Cthulhu_ wrote: post #108
dsr_ wrote: post #89

Earlier quoted context omitted.

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.

I think for comparison, this (and the Wankel) would have to do two rotations for a single cycle.

Typical Otto cycle 4-stroke piston engines do two rotations for a single cycle. Wankels are more complicated; each rotor face acts as a separate combustion chamber and all four strokes happen in a single rotation. It looks like the situation is similar with LiquidPiston's implementation.

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

#136

Post by mcronce »

0cf8612b2e1e wrote: post #129
bluGill wrote: post #97

Earlier quoted context omitted.

Every motorcycle mechanic I've seen has a sign in the shop: speed costs money, how fast do you want to go. That sign isn't referring to the costs to modify an engine to go faster so much as the cost to constantly rebuild the engine after they modify it to go fast. I've seen two identical engines, one rebuilt to stock and one rebuilt to max speed - the cost for both rebuild jobs was about the same (the parts for speed…

What is done to modify an engine for speed? What kind of improvement can be seen for speed (accelerates XX faster? YY higher top speed)?

Simplifying things in this comment a fair amount, but...

Extracting more power is, most commonly, a matter of burning more fuel, which requires more oxygen. This increases combustion chamber pressure, which drives the piston down with more force; that force is converted to rotational torque and ultimately drives the wheels harder, pushing the vehicle forward faster.

More oxygen can be added in any number of ways; less restrictive intake/exhaust parts, larger valves, cams that are more optimized for whatever load/engine speed you want to produce peak power (or are more optimized for output than, say, economy or emissions), supercharger, turbocharger.

Adding fuel is more straightforward: A higher capacity pump and/or bigger injectors/carbs.

You can also switch to pistons that will compress the air/fuel charge more. This also increases combustion chamber pressure.

You can also run the engine at a higher speed, which will often warrant different cams, stronger valve springs, etc. May also require bottom end uprated components that can handle that task (connecting rods, pistons, bearings, crankshaft).

On the subject of bottom end components, depending on how much you increase cylinder pressure, you may need to upgrade those.

You can also increase output power by reducing losses - a lighter flywheel is a common example with enthusiasts.

Every single one of these involves a trade-off. A lighter flywheel impacts drivability; removing intake/exhaust restrictions and adding forced induction components will both make more noise; etc.

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

#137

Post by adgjlsfhk1 »

themaninthedark wrote: post #121
Cthulhu_ wrote: post #106

Earlier quoted context omitted.

I think a lot of commenters in articles like this will only think about automotive as a use case for alternative engine designs. I'm reminded of a linear piston engine (iirc two pistons that just go back and forth without their motion being translated into rotation; one where they were side-by-side moving alternately, the other one where they'd actually move towards each other and share a combustion chamber). The use…

My first thought went to cargo ships. They require huge motors, so I imagine that if you can keep or gain performance while reducing size they would be very interested.

this is backwards. the reason cargo ship engines are big is because they don't care about size. they would rather have a 2x bigger engine that was 1% more efficient

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

#138

Post by garaetjjte »

CharlesW wrote: post #133
garaetjjte wrote: post #132

Photo clearly shows spark plugs on it, and they claim it runs on diesel, so which is it? I don't think spark ignited diesel would work very well.

How do you know they're spark plugs and not glow plugs?

Glow plugs don't have HV insulator.

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

#139

Post by aidenn0 »

bmelton wrote: post #54
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.

Agreed, but there's also Koenigsegg, which has managed to eliminate the need for cams, and complete heads from ICEs, replacing them with their 'freevalve' tech (which basically replaces the timing chain with computers so that instead of having one or two modes that a camshaft can opt into, you can precisely dial in bespoke timings for every RPM, or every RPM and speed, or ever RPM / speed / gear combination. They've…

People have made test engines with camless electrically actuated valves for a long time; it's just been too expensive to put in production cars...

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

#140

Post by Cockbrand »

KAMSPioneer wrote: post #32
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.

Yes, it’s a bit hard to explain, and I’m not a native speaker. But you got me right, and now I see that too. Thanks for the heads up!
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