LiquidPiston – The combustion engine reimagined
invest.liquidpiston.com
invest.liquidpiston.com
If this was going to revolutionize anything, it would've happened by now.
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.
https://cleantechnica.com/2020/09/22/everything-you-need-to-...
https://electrek.co/2023/04/21/tesla-update-4680-battery-cel...
Honestly, Tesla Energy is looking to eclipse Tesla as the main source of recurring revenue.
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
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.
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/
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!
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.
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.
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.
But the fact companies make normal wankel engines that are better at everything is worrying for them
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.
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.
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?
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.
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...
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
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.