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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

#101

Post by bluGill »

codeflo wrote: post #83
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?

I know this is off-topic, but I'm curious. I always had the impression that even in the US, standard units are used for engineering. Reading about "ft-lb" makes me think I was wrong (and my head hurt, tbh). Do you really compute stuff like torque in imperial units? Don't you need weird factors in every formula to make that work?

There are lots of weird factors in engineering anyway. We have different factors, but there are still factors. Besides, nobody is calculating this, they are measuring and that is just a matter of what label you put on the dial.

Most engineering in the US is done in metric units. Then marketing applies a metric to imperial conversion.

I suspect China does more engineering in imperial than the US, both in total an per capita: most things I buy made in America are all metric (cars are all metric except for parts designed in the 1960s and the adapter bracket to make them fit on a modern metric car). Most things I buy made in China are imperial. I don't really know for sure, but that is my impression of industry.

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

#102

Post by bluGill »

bell-cot wrote: post #57
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?

Their target market is the military - which has plenty of kerosene / jet / diesel fuels as part of its standard supply chain. The Camry engine will only run on gasoline - which the military neither carries, nor wants to.

Toyota makes some great diesel engines (they don't put them to the US bound products in general), which could run on jet fuel with some small modifications.

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

#105

Post by [deleted] »

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.

[deleted]

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

#106

Post by Cthulhu_ »

Zak wrote: post #33
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.

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 case for that was to have the pistons move through coils, thus generating electricity. We used to have a flashlight that works with the same principle, shake it to generate electricity.

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

#107

Post by DesiLurker »

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 output of a electric motor.

If traditional carmakers had done that research about 10 years ago they wouldn't be facing such crisis with EVs today. a high-efficiency multi-fuel range extender engine is all we need today but still I cant find many automakers jumping on it.

PS: it would have been nice to see a micro-turbine based generator with high thermodynamic efficiency but my understanding is that need a lot of maintenance so not suitable for consumer applications.

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

#108

Post by Cthulhu_ »

dsr_ wrote: post #89
elihu wrote: 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.

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

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

#109

Post by jdmichal »

bmelton wrote: post #36
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.

I always wondered why "electric with an onboard generator" didn't take off as a subset of available vehicles. AFAIK, hybrids all work with complex gear boxes to allow the engine to directly power the wheels, while also charging the batteries.

I suspect the answer is because it's more efficient from a MPG perspective to allow the engine to directly power the wheels, at the cost of the extra complexity of gearing. Converting motion to electricity back to motion is lossy, and even more so if you insert battery storage as an additional step.

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

#110

Post by driverdan »

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 regulations have resulted in very few vehicles with ICE range extenders. Existing engines are easily capable of maxing out that regulation so there's no incentive to research other engines.

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