I'm assuming the purpose of developing a more efficient engine is to reduce emissions and thus "saving the planet"? That may seem commendable, but from what I have read it is actually a wasted effort, unless you can make it 99%+ more efficient (which you cannot). So, even if this engine is all that it claims (which most other comments here seems to question), it still uses oil and therefore is part of the problem and not the solution. (Wrote abit about this a while back with more references: <a href="http://torkeldanielsson.se/reducing-emissions-is-not-enough" rel="nofollow">http://torkeldanielsson.se/reducing-emissions-is-not-enough</a>)<p>Edited comment: Man, I don't get hacker news... Why do you downvote this? I thought I was adding a valid and important point - that an increase in efficiency is fighting the wrong battle. I even added references via link. I would be super happy if I could be informed of what in this post is offending or off topic!
There is this guy who has made some similar engine prototypes in this field of efficient opposed piston engines.<p>PatOP: Single-Crankshaft Opposed-Piston Engine<p><a href="http://www.pattakon.com/pattakonPatOP.htm" rel="nofollow">http://www.pattakon.com/pattakonPatOP.htm</a><p>OPRE: Opposed piston Pulling Rod Engine<p><a href="http://www.pattakon.com/pattakonOPRE.htm" rel="nofollow">http://www.pattakon.com/pattakonOPRE.htm</a><p><pre><code> > A 500cc two stroke can easily make some 80 Nt*m (8 Kp*m) torque.
> At 6000 rpm this torque makes some 50 KW (70 PS).
> 50 KW from 20 Kp means 0.4 Kp per KW.
> And 0.4 Kp/KW with direct injection Diesel efficiency sounds interesting, especially for an engine with such a low cost."</code></pre>
So, as I understand it, it combines the compression ignition of diesels with opposing pistons. The opposing pistons go toward one another and compress the air/gas mixture and ignite it. The exhaust escapes when the pistons move back through ports machined in the sides (kind of like a wankel/rotary engine removes exhaust gasses).<p>Sounds like they're trading the spark system (a pretty easy to maintain system) for a second piston/crankshaft/etc. Essentially pulling out a cheap and perfected system for one that adds a bunch of high stress, expensive parts. Just from that sounds like a bad idea.<p>They say the extra efficiency comes from heat loss from the cylinder head, but I have a hard time believing they're capturing that much extra (double-digits) efficiency from heat loss alone, especially given the reduced efficiency of having more moving parts.
"The new engine will meld the best characteristics of gasoline and compression ignition engines with an innovative piston architecture refined by Achates Power that sets two pistons moving in opposition in one cylinder."<p>We already have this technology. Diesel engines ignite the fuel through compression. We also had the opposing pistons layout for a while (<a href="https://en.wikipedia.org/wiki/Opposed-piston_engine" rel="nofollow">https://en.wikipedia.org/wiki/Opposed-piston_engine</a>).<p>EDIT: we even have triangular-y shaped opposing engines (<a href="https://en.wikipedia.org/wiki/Napier_Deltic" rel="nofollow">https://en.wikipedia.org/wiki/Napier_Deltic</a>)
Efficiency aside, big two-stroke engines, particularly diesels, tend to have a very distinctive sound. I guess this one, being also two-stroke and compression ignition, would probably sound somewhat like this:<p><a href="https://www.youtube.com/watch?v=mkH9QRaQJM0" rel="nofollow">https://www.youtube.com/watch?v=mkH9QRaQJM0</a><p>Even if they weren't all that much more efficient, I bet a lot of people who miss the 2-stroke diesel sound would want one in their car.
I thought that gas based engines topped out at 30% due to the heat loss intrinsic with burning fuel(all that waste heat). Is this tackling that in some fundamental way or is it just an incremental improvement?
Opposed pistons have had good success in marine and railroad applications.<p><a href="https://en.wikipedia.org/wiki/Fairbanks_Morse_38_8-1/8_diesel_engine" rel="nofollow">https://en.wikipedia.org/wiki/Fairbanks_Morse_38_8-1/8_diese...</a>
Opposed pistons is a way to have a very long stroke engine (high torque and smaller piston speeds = smoother), without the bigger radius that the crankshaft pin would have to rotate.
Large engines (in giant container ships) are supposed to be approaching the efficiency limit according to theoretical thermodynamics. Does this get small engines close to the limit?
Achates power has been running engines on test stands since 2011, I haven't heard of any engines installed anywhere.<p>Maybe this kind of business is different compared to software where you're expected to build something revenue generating relatively quickly.
This is not the same thing as from the article, or even a gas engine, but it reminds me of this project. I never found out what became of this: <a href="http://www.nytimes.com/2000/09/19/science/putting-a-darwinian-spin-on-the-diesel-engine.html?pagewanted=all" rel="nofollow">http://www.nytimes.com/2000/09/19/science/putting-a-darwinia...</a><p>>Dr. Senecal's test engine consumed 15 percent less fuel than a standard engine while producing one-third as much nitric oxide and half the soot.
> The research is being conducted under a three-year project funded by a $9 million award from DOE's Advanced Research Projects Agency-Energy (ARPA-E) and an additional $4 million of cost share from the team members.<p>So, the total cost of designing this prototype was $13 million? What's the size of the R&D budget for a typical automaker?<p>To me this just shows that typically businesses are in the mindset of "business as usual" because it's what they are comfortable with rather than looking into radical, new, innovation.
<i>cough</i>
I'm going to leave this here....<p><a href="https://en.wikipedia.org/wiki/Napier_Deltic" rel="nofollow">https://en.wikipedia.org/wiki/Napier_Deltic</a>
HCCI is difficult enough--high compression ratio requires strengthened materials. Plus there's the hydrocarbon issues that come up with low temps. Maybe the heat retained by not having a cylinder head would be able to compensate? High temp burn/lean burn can lead to high NOx which is pretty bad if you need a urea injector system.<p>Mazda, GM and others are known to be working on CI engines for gas targeting 2020, so this might be the next step in 10 years. Assuming we don't all switch to pure electric...
While several people have mentioned the Napier Deltic, there was also the Junkers Jumo 205 opposed-piston diesel aero engine of the early 1930s.<p><a href="http://www.enginehistory.org/Diesels/CH4.pdf" rel="nofollow">http://www.enginehistory.org/Diesels/CH4.pdf</a><p>Claims of innovative internal combustion engine designs that will be significantly more efficient than current ones show up every few months. They never live up to the hype.
Hopefully DOE also has $9 Million or more invested into battery research for electric motors.<p>But I guess $9 Million isn't unreasonable if it actually produces engines that automakers will adopt.
While not an earth-shattering amount, I'd rather see such grants/cost sharing go to tech that doesn't perpetuate dependence on fossil fuels. In the end, this tech only means we get to burn less, but not eliminate the emissions all together.