LiquidPiston – The combustion engine reimagined(invest.liquidpiston.com)

28 pointsby ciurca3 tahun yang lalu48 comments

invest.liquidpiston.com

LiquidPiston – The combustion engine reimagined

https://invest.liquidpiston.com/

49 comments

xnx3 tahun yang lalu

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.

bogwog3 tahun yang lalu

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.

Cthulhu_3 tahun yang lalu

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.

ngvrnd3 tahun yang lalu

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.

ImPostingOnHN3 tahun yang lalu

there isn't a single product elmu could produce for which a tenuous connection couldn't be imagined

apples? well he's just learning about agriculture, which we will need on Mars

toilets? well, people poop on Mars, too

overpriced AV cables? well, obviously Mars will need high end cables for stuff

basch3 tahun yang lalu

You would need a lot of the same tech to terraform Earth, or make Earth habitable, if it became unso.

kamranjon3 tahun yang lalu

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

7jjjjjjj3 tahun yang lalu

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

dreamcompiler3 tahun yang lalu

If you have evidence that Tesla doesn't make batteries, perhaps you should alert their shareholders that the company is lying on this page:

https://www.tesla.com/giga-nevada

taylodl3 tahun yang lalu

You're both right. Tesla doesn't make battery cells, they make battery packs. A battery pack is comprised of several battery cells, for example the Model Y has over 4,000 cells in its battery pack.

dreamcompiler3 tahun yang lalu

They certainly appear to be making cells now too.

https://cleantechnica.com/2020/09/22/everything-you-need-to-...

https://electrek.co/2023/04/21/tesla-update-4680-battery-cel...

taylodl3 tahun yang lalu

Wow! That's huge! They're doing a good job of positioning themselves as being the world's best source of batteries.

Honestly, Tesla Energy is looking to eclipse Tesla as the main source of recurring revenue.

ngvrnd3 tahun yang lalu

cells are not the same thing as batteries; it's possible tesla is making batteries with cells from Panasonic or whatever.

toss13 tahun yang lalu

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

aredox3 tahun yang lalu

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.

toss13 tahun yang lalu

>>The main selling point of LP would be in durability

Um, I haven't seen them significantly promote that even rhetorically, much less with data backup. Replacing Wankel's ordinary tip seals with ceramic tip seals (yes, more expensive) and proper lubrication both improves performance and very much extends inter-rebuild time.

I'm definitely interested if you can point me to any data showing LP extended life. Their previous comparisons have been so bogus as to be laughable, such as comparing their weight vs some old military diesel generator-set (and not to the much more relevant Wankel).

>>LP doesn't seem to execute well. Agree - that is the understatement of the year!

aredox3 tahun yang lalu

LP doesn't execute well, so I don't think they can have data showing their engine has a better life span (which is dependent on more than just these seals). It just makes sense from an engineering, "first principles" point of view.

ktm5j3 tahun yang lalu

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

rjmunro3 tahun yang lalu

> 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.

pfdietz3 tahun yang lalu

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".

canbus3 tahun yang lalu

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

chipsa3 tahun yang lalu

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.

stefncb3 tahun yang lalu

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.

2-718-281-8283 tahun yang lalu

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.

stefncb3 tahun yang lalu

This isn't all that different from a four stroke, at some level. With a piston engine you lubricate from below, the oil never getting above the rings. Practically some does and gets burned away, but that's negligible usually. Anyway, the seals on the liquidpiston engine supposedly do the same, keeping the oil from leaking around the seals (in a significant quantity anyway; I'm sure it's higher than a four stroke though).

Here's what their webpage says:

> The seals do not experience centrifugal forces, and can be lubricated directly by metering small amounts of oil directly to the sealing surface through the housings, which means that oil consumption can be reduced to levels potentially comparable to that of a 4-stroke piston engine (essentially negligible).

Obviously take all this with a grain of salt. I haven't read any practical studies on this.

drcongo3 tahun yang lalu

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

canbus3 tahun yang lalu

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

ilyt3 tahun yang lalu

Yeah but "just replacing $50 seal every few years" is smaller problem than "taking apart whole engine to replace the $50 seal". And now they can technically be directly oiled instead of whole oil in petrol thing.

2-718-281-8283 tahun yang lalu

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

stefncb3 tahun yang lalu

If you look at an image, you can see the three apex seals on the stator, which is shaped the same way as a wankel rotor. The rotor of the liquidpiston engine is shaped similarly to the wankel stator and has no seals. It's almost the same just turned inside-out.

2-718-281-8283 tahun yang lalu

true - now i see it.

TheCondor3 tahun yang lalu

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.

toss13 tahun yang lalu

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.

ilyt3 tahun yang lalu

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

0x4454423 tahun yang lalu

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.

UncleEntity3 tahun yang lalu

> 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.

obituary_latte3 tahun yang lalu

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).

toss13 tahun yang lalu

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.

linuxftw3 tahun yang lalu

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.

ilyt3 tahun yang lalu

> 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?

linuxftw3 tahun yang lalu

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.

ilyt3 tahun yang lalu

>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.

Their comparison was essentially for mostly-constant RPM usage (generators,UAVs), rather than something more dynamic. Which means they can just peg the engine at most efficient point, just like Mazda's range extender wankel. So yeah, not for tractor-like usages.

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

No, torque on its own is not, else you could compensate with gearing. Power (and in relation, torque) curve is the important one.

The "tractor" like uses want "constant power" across the range, which essentially means flat-ish power curve across whole range[1], and that means torque is dropping fast with RPM. This "theoretical" one liquid piston one is probably classical high-revver curve which is near-constant torque across most of the range and very small range of peak power.

Just the torque number tells very little about that, you need a graph.

* [1] https://www.darksidedevelopments.co.uk/Blog/reading-a-dyno-g...

cwmma3 tahun yang lalu

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.

ilyt3 tahun yang lalu

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

zokier3 tahun yang lalu

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

ilyt3 tahun yang lalu

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

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

kitd3 tahun yang lalu

Video describing the engine:

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

lebuffon3 tahun yang lalu

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.

[deleted]3 tahun yang lalu