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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

#61

Post by eYrKEC2 »

qbrass wrote: post #49
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.

It actually happens less on this engine than piston engines because the lobe on the rotor kind of rotates over the combustion chamber for a while instead of moving towards or away from it. On the other hand, it exposes a lot of surface area to heat, which gets absorbed by the rotor but isn't used to turn the engine. It's a problem it shares with wankel engines. The advantage over wankels is the extra time air and fue…

I know this goes towards steam-engine design, but why can't that heat be re-captured as steam? When the engine heat gets above a threshold, inject [distilled?] water instead of fuel.

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

#62

Post by HPsquared »

vvillena wrote: post #31
skullone wrote: post #7

Earlier quoted context omitted.

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?

I guess the range-extender application is also less likely to suffer from the effects of lots of short trips.

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

#63

Post by Gordonjcp »

projct wrote: post #40
Gordonjcp wrote: post #9

Earlier quoted context omitted.

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.

Mazda addressed both of those issues, Rotax addressed both of those issues, Norton addressed both of those issues, NSU addressed both of those issues, Comotor addressed both of those issues...

The issues remain fundamental, and largely unaddressed.

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

#64

Post by aidenn0 »

syrrim wrote: post #55
seabird wrote: post #42

Earlier quoted context omitted.

You can't just make the Traxxas 18x bigger and get linear performance improvement. Trying to compare power/weight between engines with radically different weight constraints is silly.

If you had 18 such engines it would get you precisely 18x the performance, at precisely 18x the weight.

And precisely 1/18 the MTBF

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

#65

Post by [deleted] »

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?

[deleted]

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

#66

Post by someweirdperson »

Syonyk wrote: post #50
causi wrote: post #38

Earlier quoted context omitted.

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?

If it's an aviation engine, it'd better be able to!

Multiple thousand at max power? Typically, overhaul at 2000 hours. And maximum continous power isn't usually full load.

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

#67

Post by Retric »

syrrim wrote: post #55
seabird wrote: post #42

Earlier quoted context omitted.

You can't just make the Traxxas 18x bigger and get linear performance improvement. Trying to compare power/weight between engines with radically different weight constraints is silly.

If you had 18 such engines it would get you precisely 18x the performance, at precisely 18x the weight.

No, because you would need to add structural elements, some way of combining power output, and cooling if you’re aiming for a similar form factor.

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

#68

Post by ww520 »

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.

The problem with rotary engine is that its max power efficiency is at a very narrow rpm range and loses power at most other rpm ranges. This is due to the constant air intake inherent in the design. Piston engine has variable valve air intake to ensure optimal air oil mixture compression to deliver max power efficiency at a long range of rpm’s. That’s why rotary design is not popular for cars.

Mazda is reviving small single cylinder rotary engine design for HEV by running it at a constant speed with max power efficiency to charge the battery.

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

#70

Post by Enginerrrd »

rascul wrote: post #48
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.

Some years past, a friend who worked for Mazda explained to me that the engines need to be driven for a bit because until they're warmed up fully there can be a lot of carbon buildup and it needs to be run some amount of time to get the carbon through. Once they're warmed up and running for a bit they're fine. Supposedly it's the short trips of only a few miles that can kill them over time. Not sure if that's correct…

Yeah I talked to some race mechanics that said the mazda rotary engines had much better longevity if you really drove the piss out of them. They liked to rev high and hard, which would be basically consistent with that notion.
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