LiquidPiston – The combustion engine reimagined

https://invest.liquidpiston.com/

by ciurca • 3 years ago

28 48 3 years ago

invest.liquidpiston.com

canbus2• 3 years ago

hmmm.. still uses apex seals, would need seriously small tolerances to make it work effectively. Call me skeptical but I don't see how this is really any better than the traditional wankel/rotary design

stefncb3• 3 years ago

It's effectively an inside-out wankel, so the seals are stationary. This is a much easier problem to solve, and now you don't need to throw oil in the combustion chamber to lubricate the moving seals.

drcongo• 3 years ago

Thanks both, I'm not very mechanical and came to the comments to find out what makes this not a wankel.

2-718-281-8283• 3 years ago

to me it still looks like its principally a wankel motor just with a few changes.

canbus2• 3 years ago

right, but any float in the main eccentric shaft is still going to wear them out

2-718-281-8283• 3 years ago

problem one will be balancing forces if combustion is taking place on one side. also i don't see why this should be burning less oil. you are smearing the oil constantly around.

chipsa• 3 years ago

It inverts where the apex seal goes. So instead of having it on the rotor, and hard to lubricate, it goes on the housing, which is much easier to lubricate.

TheCondor• 3 years ago

Small, multi-fuel, engines do have interesting applications. I tend to agree though. The other big thing, these rotary engines have traditionally had poor combustion. Direct injection and turbulent jet ignition have focused on improving combustion efficiency and made tremendous gains. I’m not sure how liquidpiston addresses that, especially with the fuel claims. Traditionally you’d add fuel additives to help with combustion efficiency.

toss14• 3 years ago

You are right - it is not better - not even close.

It is 2-4X WORSE on Liquid Piston's main advertised claim to fame "lightweight" "power/weight" than many available actual Wankel engines.

And the fact that this is still in development a decade+ later and 7-8 years after I was first vetting them for a hybrid multirotor drone company indicates that your suggestion is correct — they have many nagging and serious not-easily-solved problems.

ilyt6• 3 years ago

Well, they are on outside. Which means possible way to replace it without tearing the engine apart. And we did get better at making them. And they could possibly even be oiled directly from there.

But the fact companies make normal wankel engines that are better at everything is worrying for them

rjmunro• 3 years ago

Hydrogen may be generated by renewable sources such as solar energy, making it overall a cleaner alternative than batteries on a well to wheel basis

Err, what? I guess you could contrive a scenario in which the extra solar panels and equipment needed for generating, managing and storing the hydrogen was less "well" than the batteries for equivalent "wheel" output. Perhaps if you make infrequent but long journeys, so you need a big battery, but only a small amount of power generation, but hydrogen is a very inefficient way of storing electrical power, maybe 50% of the energy back compared to over 90% with batteries.

pfdietz• 3 years ago

Right. Hydrogen only makes sense for leveling over very long periods, and then only when the capital cost of the hydrogen storage tank is low enough (for example, storing it underground like natural gas is stored) so this can overwhelm the "cost of inefficiency".

kitd• 3 years ago

Video describing the engine:

https://www.youtube.com/watch?v=0e785YnDmq0

xnx• 3 years ago

Posts on Hacker News related to LiquidPiston go back 11(!) years. The most comments are on this post: https://news.ycombinator.com/item?id=25450477

If this was going to revolutionize anything, it would've happened by now.

Cthulhu_• 3 years ago

I think any engine design that was popularized was backed by a car company, even the Wankel engine. If they want to make this design popular, they need to design products around it so their claims are proven.

I mean I still don't believe Tesla's primary business model is cars; the competition is outselling them left right and center. Theirs is batteries and charging infrastructure. That's a huge market that can fuel the company for a century if they play their cards right.

7jjjjjjj• 3 years ago

Tesla doesn't make their batteries, they buy them from Panasonic.

kamranjon• 3 years ago

Is Tesla really doing that bad at sales? The Model Y just became the worlds best selling car.

ngvrnd2• 3 years ago

I have this feeling that all of Musk's comnpanies are technology development ventures intended to support his primary goal of getting humans to live off-earth. Note: I am not defending his goal, or idolizing him. But consider: boring company: finance learning about tunnel construction; tunnels needed on moon or mars for habitation; solar cells: very useful on moon or mars; hyperloop: finance learning about vacuum seals and related technology. My explanation makes much more sense for each of these than the ostensible goal of the company. which brings me to the point in Cthulhu's post: tesla is selling cars to understand the techne of energy storage for use in space habs.

bogwog• 3 years ago

The overproduced site/video gives off strong crypto scam energy.

There’s a big INVEST NOW button with a very low dollar amount, and I like how they even threw in the line about being an immigrant from Ukraine as if to capitalize on current events.

I’m sure they’re not a “scam” though, just a poor investment.

toss14• 3 years ago

Yup

Seven-ish years ago while working on a hybrid-powered UAV I was checking out high power/weight engine platforms. I found a significant variety of regular Wankel engines that had MUCH better power/weight ratios and were available for purchase (not "real soon now").

Since power/weight is Liquid Piston's main claim to fame, this is rather important.

Today, a quick DDG search similarly returns many Wankel-based engines that definitely have better powr-weight ratios than Liquid Piston. The primary markets seem to be lightweight aircraft and some motorbikes.

The first one is AIE 80S [0]. It puts out 15BHP/11.2kW at 5kg/11 Lbs.

AIE's 225CS puts out 40BHP/30kW at 10kg [1].

In contrast, Liquid Piston's XS-210 weighs 21kg/46.7 Lbs to produce 19kW/26HP (third page of PDF spec sheet in button on [2]).

The net power/weight for these Wankels is 2.24kW/kg and 3.0 kW/kg. Compare this to the Liquid Piston XS210 0.9kW/kg. Liquid Pistoin's main advertised performance is between 1/2 and 1/3 of an already available Wankel. And there are many more Wankel options.

Plus, despite power/weight being Liquid Piston's main claim to fame, I have to wade through multiple pages, multiple "Invest Now!" popups, to finally dig down to their PDF spec sheet to even find an actual weight figure. In contrast, whereas the Wankel's pages post it right up front.

It is quite obvious that the Liquid Piston people know that they are not even close on their main claim to fame, yet are willing to just act as if they are the best available and count on people not actually doing their due diligence.

They literally look like they are in the same position as 7-8 years ago, "ohh we have this great lightweight new technology, shipping real soon now -- get in on the ground floor!!" I used to look at it as "maybe they'll get better". But at this point, it is pretty clear that they know they have nothing groundbreaking and are just trying to ride it as long as possible.

TBF, they MAY have a possible market using JP-8 fuel which is widely used and available in military contexts. But Wankels have been adapted to many different fuels and it would only be a temporary advantage if someone wants to get into this market.

Don't be parted from your money here....

[0] https://www.aieuk.com/80s-15bhp-wankel-rotary-engine/

[1] https://www.aieuk.com/225cs-40bhp-wankel-rotary-engine/

[2] https://www.liquidpiston.com/xts-210-engine

ktm5j• 3 years ago

Thanks for this, I really appreciate the real data and perspective

aredox2• 3 years ago

The main selling point of LP would be in durability - I'm sure once liquidPiston patents are expired, better engineering firms will produce better Wankel engines with their design. LP doesn't seem to execute well.

obituary_latte• 3 years ago

Unless they are getting some miraculous increase in efficiency compared to any other Wankel engine (see Mazda), I don't see the value add here. It's essentially just a different way to do what the Wankel does with a few differences (apex seal placement, rotor shape and function).

toss14• 3 years ago

They are not. There are many available actual Wankels in multiple sizes and power outputs. They ALL provide far better power-weight ratios — like 2.4X better — than this still-in-development-after-a-decade+ 'product'. More details in other post.

0x445442• 3 years ago

The video on the main page had me until they said their main focus now was on helping the U.S. empire's attempts to subjugate the rest of the world. If small form factors were a focus, how about off grid generators or the like. Leading with military applications does not inspire IMHO.

UncleEntity• 3 years ago

If small form factors were a focus, how about off grid generators or the like.

Which is probably why the military is interested in it.

If it runs on diesel all the better as they have pretty much standardized on JP8 for all their subjugation needs.

lebuffon• 3 years ago

Legacy technology always "improves" when a serious disruptor enters the market. It seldom can overcome the disruption for very long.

However this engine seems to be a great improvement on pistons if we want to continue burning dinosaur juice. It might be interesting to try it as a range extender for long-haul electric trucks due the smaller size and weight.

linuxftw2• 3 years ago

On the one hand, it seems like they have an addressable market. On the other hand, it seems like a scam because they're trying to attract investors with a fancy web page and thin statements about where they're actually selling.

The comparison to a 25HP Kholer on the main page is... something. Here's the 'brochure': https://uploads-ssl.webflow.com/5f6086e9bbbabd41a20f2984/642...

Less than half the torque at more than double the RPMs. And very low compression, I don't see how this can run diesel.

ilyt6• 3 years ago

Less than half the torque at more than double the RPMs.

I mean if you double RPM you halve the torque at same power, dunno what's weird here ? It's smaller CC faster rotating engine.

And very low compression, I don't see how this can run diesel.

I'm also on "show us the working engine" side but supercharger will also add some heat and pressure to the system it might work?

linuxftw2• 3 years ago

They're comparing a small engine to a 25HP diesel engine. A 25HP diesel is what powers my tractor, they're really not in the same class as a small 25HP gasoline engine that powers my lawnmower.

If we're comparing the usefulness of an engine, torque is a big part of the equation.

If they can get a small diesel engine for light load applications like generators or small aircraft, that might be a win so the military doesn't have to bring a different type of fuel (gas) or a heavier diesel engine.

But I'm not sure 8:1 compression ratio is enough to operate the diesel cycle.

zokier• 3 years ago

Apparently they have 210cc 25hp engine available.. is there any reason someone (or they themselves) couldn't throw that into a bike to see how it performs in real-world? There are plenty of 250-300cc bikes around with comparable power ratings, so you'd think it'd be feasible project and a bike sounds much simpler than car/aircraft/etc

ilyt6• 3 years ago

Well, if you want Wankel in your bike...

https://www.aieuk.com/225cs-40bhp-wankel-rotary-engine/

cwmma• 3 years ago

This is basically a variant of the Wankel engine, and if you do a cursory view of the Wankel engine wikipeida page it paints a pretty clear picture of a theoretically better engine that ends up not performing as well as standard engines due to a 1000 little things like the seals, ignition and chamber shape that have been perfected over the century + of normal engine designs. This engine is going to have all those problems and more preventing it from being as good as a regular engine in practice.

ilyt6• 3 years ago

It does solve few of them, althought it doesn't look it will be easy to scale to more than one engine.

For example the apex seals being on "the outside" instead of on the rotating assembly means they could be made easier to replace and easier to oil too.

But yeah, improvements look not all that big, certainly not revolution

LiquidPiston – The combustion engine reimagined

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