EcoMotors Teams with Navistar to Produce Turbo Diesel OPOC Engine

EcoMotors signs agreement with Navistar

EcoMotors signs agreement with Navistar

Unlike some innovative engine designs perpetually hyped as the engine of the future, EcoMotors' OPOC engine seems to be making real headway. They have reached an agreement with Navistar to build a 2 module turbo diesel version for Class 8 trucks, designed to produce about 480 hp, it could deliver as much as 45% better fuel efficiency than the standard heavy duty diesel engines currently used.

The two stroke OPOC engine looks like a really versatile package. With 2 cylinders and 4 pistons in each module, there's no cylinder head or valve train. The modules can be joined to increase the number of cylinders, raising power levels to whatever the application requires and a clutch between modules means you can power modules up and down as needed. With the addition of an electrically controlled turbocharger, which can be spun up before engine start, even more power is available. You have to think a small version of this would be a nice fit for a touring or adventure motorcycle.

The OPOC engine is smaller and lighter than a 4 stroke but has low emissions, plus fewer parts mean less friction for greater efficiency. The opposed pistons decrease stroke allowing higher rpm. With the opposed pistons, the pushing and pulling of opposing rods balance forces, making possible a low stress, lightweight crankshaft.

The engine can also be converted to gasoline or alcohol fuel.

This is a very cool technology and it doesn't need some battery breakthrough to be truly useful, it uses the fuel infrastructure already in place and it's built using conventional materials and processes. I see this as an engine with a real future and it's already looking like the first commercial application is on the way. I like it.

The first video below shows the joined modules running either paired or alone. The second video has a nice Q&A session with lots of explanations. Worth watching.

Link: Navistar and EcoMotors via Next Big Future

Previously on The Kneeslider:
EcoMotors OPOC Two Stroke Engines – Opposed Piston Opposed Cylinder
EcoMotors OPOC Two Stroke Engine Gets Funding from Bill Gates

Videos below:


  1. Tinman says

    This could be the real deal, a breakthrough new tech that actaully makes production. Use our massive supplies of Dead Dinos in the most efficiant means possible. Bring it on.

  2. mustridemore says

    This proves that you can do just about anything when you have the proper funding and resources.

    • Paulinator says

      The senseless architectual mutilation of the Royal Ontario Museum proves that you can do anything with the right funding and resources (connections)…still doesn’t mean you should.

      This effort should be re-named the “opposed-objectives” engine.

  3. says

    The PatOP engine (at ) with a basic module comprising one only cylinder and two only opposed pistons is better balanced than the two-opposed cylinders four-opposed-pistons basic module of the OPOC engine of EcoMotors.

    The PatOP engine provides some 20% additional time, as compared to the OPOC of EcoMotors, for more efficient injection, penetration, vaporization, and combustion of the fuel spray (at high revs the additional time enables higher peak power, at medium-low revs the additional time enables better efficiency and lower emissions).

    The PatOP engine has constantly zero total force on the main bearings of the crankshaft (the connecting rods of the two opposed pistons remain constantly parallel, have normal size and are heavily loaded only in tension, i.e. they are pulling-rods).

    The PatOP engine intergrades a “volumetric”, piston-type scavenging-pump that enables a flat torque curve in a wider rev range. The turbo-charging is an option.

    The PatOP engine takes the thrust loads away from the hot cylinder walls and away from the ports, enabling far lower lubricant consumption and better lubrication, just like the giant cross-head Sulzer engines; because the PatOP is a cross-head engine, yet a short one (for 79.5mm bore and 64+64=128mm stroke, the PatOP is only 500mm long); the inner-exhaust piston skirt of the OPOC of EcoMotors cannot help thrusting heavily onto the hot cylinder wall, over the exhaust port openings, increasing lubricant consumption and decreasing piston / cylinder life.

    Can somebody from EcoMotors or Navistar tell what are the advantages of the OPOC engine over the PatOP?
    Or over the OPRE engine (at ) ?

    Manousos Pattakos

    • aaron says

      I can say it, but I can also say no cornering clearance with all that extra crap hanging off the end of the already wide boxer motor. the only way I see this in a functional bike is mounted douglas/midual style with the crank across the frame

      • leston says

        Engine mounted front to rearl. You’d have to deal with a drive shaft but nothing that couldnt be handled with a little engineering.

  4. Arion says

    I am not from EcoMotors or Navistar, but one advantage I see for the OPOC engine is it’s greater symmetry over the PatOP. One OPOC engine module is the equivalent of a 4 cylinder engine, while the PatOP is the equivalent of a 2 cylinder engine, although not quite, because the PatOP features that third piston for pumping/scavenging. As such I would expect some losses from that third piston. It should possible to arrange PatOP modules in opposed pairs to obtain a roughly 4 cylinder equivalent, but I expect you would be left with a greater rocking couple due to greater cylinder axes offset compared with conventional boxer and OPOC engines.

    It would be interesting to see some hard data comparing volumetric efficiency, fuel efficiency, power density, and power to weight ratio. Such data would be expensive to obtain in terms of time, effort, and money.

  5. B50 Jim says

    Alco did this in the early days of diesel locomotives; they used a crank at the top and bottom of the engine and geared them together, thus eliminating the cylinder head, which at the time was a problematic aspect of diesels. It worked well but had some problems because of the state of materials and manufacturing processes of the day. The opposed-cylinder idea is a good one and does away with most balancing issues. The OPOC takes the concept further by using a single crank — a bike designed for the dimensions of the engine would be a great runner. I still like the concept of a diesel bike and would love to see a 1-liter, oil-burning OPOC touring machine. 60 mpg wouldn’t be out of the question with plenty of torque.

  6. todd says

    I would hope it would do better than 60 mpg. A XR650L gets that and probably would put out more power than a 1-liter diesel. If you’re after torque and pulling power to tow your boat behind your adventure bike lower gearing would achieve all that too. We’re probably talking more like 100 mpg for a 1-liter OPOC diesel in a bike.

    Don’t get me wrong, I like the OPOC motor (and the PatOP better), but the thing would probably be two and a half feet wide. Maybe it’s just me. I wonder how wide it would need to be to pump out at least 80 HP (to compare with a 1st gen R1100GS).

    The PatOP is nice that it nearly eliminates thrust loading on the piston skirts and cylinder and for the fact that it can be more easily packaged within the footprint of the motorcycle frame. There does seem to be quite an enormous amount of reciprocating weight in it. I wonder why he didn’t choose to use the top piston to control the induction gasses? Then he could separate the lubrication requirements of the crank and bottom piston from the inlet charge.

    Maybe it comes down to the fact that the OPOC engine received high profile recognition with an infusion of cash from Bill Gates and the Army and the PatOP didn’t.


    • jimmy says

      Todd they are talking about 45% mileage increase in heavy trucks. That equates to 2.5 miles per gallon increase. I have owned and driven tractor trailers for 30 years now and the best you can realisticly get is 6 or if you run a lot of empty miles 7 miles to the gallon. most get an average of 5.5 thats the truth anything else you here is bs. as far as two stroke diesels go we used to have them, all be it in different configuration aka detroit diesel. they polluted way to much and now are gone from the roads. this one might be cleaner but I doubt it.

      • jimmy says

        i have a question that I think the investors should have asked. If you have the top rod always pulling and the bottom rod always pushing then you have two equal forces apposing each other therefore cancelling all power created, yes? no?

        • Arion says

          No, the pulling and pushing forces are connected to opposite crank throws and thus combine to complement one another and turn the crank shaft.

  7. Arion says

    There are thrust loads on the smallest pistons on either side of the outer combustion PatOP piston arising from their connecting rods. One question: in the still photo animations with the cylinder removed, what is keeping the outer piston coaxial with the inner piston? Was it carefully reposition for each photo?

    • GenWaylaid says

      In the PatOP design, those two things that look like little pistons are the crossheads for the top piston. They slide in guides in order to keep the piston’s motion linear. The big scavenging piston serves as the crosshead for the bottom piston, which I find mighty clever.

      Just as opposed piston engines have been around for close to a century, crosshead-guided pistons have been around for close to two centuries. Crossheads prevent side loads on the piston/cylinder interface but at the expense of side loads on the crosshead/guide interface. As long as the crankshaft rotates, side loads have to go somewhere.

      The fabrication on the PatOP prototype is very impressive. If Manousos ever mounts it to a motorcycle, it’s definitely worthy of a Kneeslider write-up. The main challenge I see with the design is lubrication. The top piston is isolated from the crankshaft and working the exhaust ports, so it will need some careful attention to keep fresh oil on its hot end of the cylinder. Likewise the crossheads need to be well-lubricated in their guides because they experience side forces.

      Direct injection should prevent unburned fuel emissions from being a problem, but the PatOP is still going to have some emissions issues. Any time the exhaust port is uncovered by sliding (and thus is in a lubricated part of the cylinder wall) you will be burning some oil. In decades past, this would have been no obstacle to commercial production.

      I’m currently keeping an eye out for a Puch SGS split-single, which works on very similar principles to these opposed-piston designs, but with the cylinder folded over so the pistons can share a crankshaft.

        • GenWaylaid says

          The answer to your question about the stop-motion is that the photos are staged, obviously. In the engine the pistons are kept in line by the cylinder and to a lesser extent the crosshead guides. In the stop-motion photos, they are simply positioned the same way. That’s why the stop-motion is shot sideways, so that gravity wouldn’t be causing the pistons to flop over as soon as the shot was set up.

  8. WestOfBen says

    I like Manousos’ PatOP and OPRE engines better. If you watch his videos and demonstrations (of which there are MANY!) you’d understand there are almost no ‘uncancelled’ forces. Putting two PatOP or OPRE engines together would be the same result. The efficiency gained by the pumping pistons would in my opinion balance out to a degree the losses – internal scavenging and positive displacement supercharging to a point.

    I like the fact that the PatOP and OPRE have greater dwell and also I can see that the forces are taken away from the hot area of the bore and pistons. The most important thing is, where is the video footage for an OPOC running?!?!? I have been watching this subject with interest for years and NEVER have I seen a video from these guys. Even a basic prototype running in a lab on a dyno with wires everywhere would be good! Manousos has videos of his running on a bench at full noise for Pete’s sake!

    The OPOC is still too complicated. Yes things can be lighter but you still have a hell of a lot of reciprocating and gyrating mass.

    • says

      yes: both the OPOC and PatOP designs still have side-loading. the only engine design i know of that has zero side-loading is the Revetec design. in the revetec engine design, they replaced the crankshaft with a *PAIR* of counter-rotating 3-lobe cams (this is absolutely critical to get zero side-loading). again, it’s an OPOC design. the balancing of the engine to achieve near-zero lateral forces is done through having 2 pairs of opposed pistons, offset at something like 45 degrees in a X.

      by having absolutely zero side-loading, in the revetec design the pistons can be dramatically shrunk (no skirts), and even made of ceramic: the only parts touching the cylinder walls are the piston rings.

      but there’s another advantage to using trilobate counter-rotating cams: unlike a crankshaft you can recover the power of the explosion for a longer period. cranks you get about 45 degrees, but with trilobate counter-rotating cams you get something insane like 120 degrees.

      the torque delivered by a revetec engine is so immense that when they did a 90HP prototype engine for a customer’s trike it was pulling wheelies from a standing start at only 10% throttle. in drag races, the trike was easily outperforming 160HP competitors with standard engines, with its nose in the air the entire quarter mile.

      well worth looking up – but please don’t bug them with enquiries unless you have a large amount of money to invest in helping them get to market, ok?

  9. WestOfBen says

    Todd, couldn’t agree more. Manousos is doing this off his own back. With some investment and refinement where would he be? I am ‘rooting’ for the underdog. Can someone in here with some spare change talk to Manousos and surely a PatOP can be built and tested in an old BMW or even a freakin go-kart!

    I still stand by it: The OPOC is in danger of becoming VAPORWARE…

  10. B50 Jim says

    Read the copy: “They have reached an agreement with Navistar to build a 2 module turbo diesel version for Class 8 trucks…”

    I doubt Navistar would sign on to a project that has no running prototypes. This ain’t vaporware; it’s the real thing. First heavy trucks, light trucks next, then cars, and finally bikes.

  11. Paulinator says

    What happens to those long pencil-thin outer rods when this thing is screaming at peak rpm and it loses spark or fuel for a split second. I wouldn’t want to be straddling it.

    There are a lot of ugly compromises in this effort that can be seen at a glance. If it ever goes anywhere it’ll be in small pieces…Junk!

  12. WestOfBen says

    OR… Darpa funding has run out and Navistar are taking a leap of faith? I hope it works out for them, however engineering and marketing failures have befallen almost every major company. Especially motor companies. If the OPOC makes it to market and is a success then I am happy because it is something new and in my mind an improvement.

    Now, I would like to hear three of these units hooked up with an open set of stacks – wouldn’t that evoke memories of the Commer-Knocker and all those Detroit 6V71s and 92s? Can it come with supercharger whine and turbo whistle.. please?!?!

  13. Arion says

    Conceptually, I like the OPRE engine more so than the PatOC. Its symmetry and simplicity are admirable, but I wonder about its torque capability. Torque is heavily influenced by crank throw (larger being better as it gives the pistons more leverage) and connecting rod length (larger being better as it reduces piston side thrust). The crank throws seem relatively small and are largely limited by cylinder bore. Also, the connecting rod length seems limited by piston length, and therefore weight. Both characteristics together would seem to place limits on relative torque capability.

    Anyway, all parties could debate all aspects of the OPOC, OPRE, and PatOC endlessly without some hard data for objective comparisons.

  14. FREEMAN says

    I’m all for the next best thing, but it does seem a bit like the same old thing with these prototype engines. Everyone has a hand-crank display model and plenty of guys willing to dish out promises of this and that. However, they never seem to get off the ground. Personally, I’m a fan of the “swing-piston engine.” But nobody seems to have a working prototype of it. I’ll believe the promises of their respective developers when I see it running on the dyno.

  15. says

    Arion: “I am not from EcoMotors or Navistar, but one advantage I see for the OPOC engine is it’s greater symmetry over the PatOP.”

    What I see in the OPOC is asymmetry. The outer pistons (those with the long connecting rods) perform a quite different motion as compared to the inner pistons. The one combustion chamber uses the outer piston to cover – uncover the exhaust ports, the other combustion chamber uses the inner piston to cover uncover the exhaust ports. The asymmetry is also in the opening of the intake ports by the outer intake piston in the one cylinder and by the inner intake piston in the opposite cylinder. To keep the same rhythm of exhaust ports opening for the two cylinders is impossible. The same for the rhythm of intake ports opening.

    Arion: “It should possible to arrange PatOP modules in opposed pairs to obtain a roughly 4 cylinder equivalent, but I expect you would be left with a greater rocking couple due to greater cylinder axes offset compared with conventional boxer and OPOC engines.”

    The opposed cylinders axes offset of the OPOC generates an unbalanced inertia rocking couple. Or not? Excluding the inertia torque (i.e. the inertia moment about the crankshaft axis, which is present in both, the PatOP and the OPOC), each cylinder of the PatOP is – alone – fully balanced as regards its inertia forces and moments. This simply means that in any two-cylinder arrangement of the PatOP (either in-line, for better packaging, or in opposed pairs), there is no rocking couple, at all.

    Todd: “I wonder why he didn’t choose to use the top piston to control the induction gasses? Then he could separate the lubrication requirements of the crank and bottom piston from the inlet charge.”

    No. The upper piston fits better to the exhaust side of the cylinder wherein most of the cooling is necessary. The big diameter piston at the bottom makes the scavenging of the PatOP, with the inlet charge neither getting into the crankcase – i.e. in the space around the crankshaft between the intake piston and the scavenging piston – nor getting in contact with the lubricant in it. So, the inlet charge of the PatOP is separated by the “lubrication requirements” of the crank and bottom piston.

    Arion: “There are thrust loads on the smallest pistons on either side of the outer combustion PatOP piston arising from their connecting rods. One question: in the still photo animations with the cylinder removed, what is keeping the outer piston coaxial with the inner piston? Was it carefully reposition for each photo?”

    Yes, it is a “careful” repositioning. The proto animation simply shows the motion of the inner parts of the PatOP engine. Without the casing, as happens in the conventional engines, too, the mechanism cannot operate.

    Quote from the article about the OPOC: “it could deliver as much as 45% better fuel efficiency than the standard heavy duty diesel engines currently used”.

    A “poor” 4.5% (four point five percent) better fuel efficiency of the OPOC over the state-of-the-art direct injection Diesels would be a great improvement. But claiming “a 45% better fuel efficiency than the standard heavy duty diesel engines” EcoMotors is obviously wrong. The fuel efficiency of the giant Sulzer engines is some 6 KWH / Kp of fuel (these engines operate near 50% thermal efficiency). Does EcoMotors means that the OPOC engine achieves 1.45*6 = 8.7 KWH / Kp of fuel? If so, they operate the OPOC engine at 72% thermal efficiency! Obviously, by the 45% better fuel efficiency they mean something else. And because they do not respond to me, the writer of the article is kindly requested to ask EcoMotors to clarify what they really mean by the “45% better fuel efficiency.”

    NAVISTAR knows better how much time-consuming the physical and chemical phenomena that take place into the Diesel combustion chamber are, i.e. how important the available time is. The table and the plots at are explanatory.
    The GIF animation at shows the upper 20% of the stroke of the piston of the OPRE / PatOP running at 6000 rpm and of the piston of a conventional running at 4500 rpm. If you cannot say which is the OPRE / PatOP and which is the conventional, neither the fuel droplets can.

    Manousos Pattakos

    • Arion says

      “What I see in the OPOC is asymmetry.” I think you have chosen a symmetry plane most people wouldn’t have selected. Granted, you have your reasons for doing so but I think the OPOC designers intended opposed cylinder pairs to be regarded as one modular engine unit.

      “Excluding the inertia torque (i.e. the inertia moment about the crankshaft axis…” I wasn’t referring to only inertia torque.

      “Yes, it is a “careful” repositioning.” Thanks for confirming that.

      I do wish you luck. Cheers.

  16. says

    GenWaylaid: “The main challenge I see with the design is lubrication. The top piston is isolated from the crankshaft and working the exhaust ports, so it will need some careful attention to keep fresh oil on its hot end of the cylinder. Likewise the crossheads need to be well-lubricated in their guides because they experience side forces.”
    Lubrication and cooling of the upper and side pistons: the side pistons are holed allowing the communication of the engine top with the crankcase through the two side cylinder passages; in addition, there are another four passages (holes) from the crankcase to the top end. The motion of the pistons generates a circulation of the air / oil-mist from the crankcase to the top end of the engine and back to the crankcase, lubricating and cooling the parts.

    The engine of Fiat 500 TwinAir is a two cylinder in line that uses a 1st order counter-rotating balance shaft to cancel the 1st order free inertia forces. The second order inertia forces remain unbalanced (as in the typical four in-line). This Fiat 500 engine has, among all the gasoline engines, the lowest CO2 emissions in the European combined cycle.
    Quote from the Engine Technology International magazine: “Driving the 85 bhp Fiat 500 TwinAir is a solid four-cylinder-like experience. No particular rattle and noise.” Also: “And when will we see the Germans, Japanese and French launch two cylinders? 2012 at the latest, guaranteed.”

    The two-cylinder four-stroke engine of Fiat 500 TwinAir fires once per crank rotation.
    The single-cylinder two-stroke PatOP engine fires once per crank rotation, just like the Fiat 500 TwinAir; besides, it is full balanced (better than any four cylinder) engine.
    It seems the single cylinder PatOP is adequate for small/medium cars and motorcycles.

    For multicylinder applications, the full balance single-cylinder basic-module of the PatOP enables the engagement / disengagement of cylinders one by one, and not two by two.
    But more important than the variable capacity is the wider rev range and the extra time granted to the combustion.

    Manousos Pattakos

    • Arion says

      What are your thoughts on the reasons opposed piston engines have not gained wider acceptance?

      What challenges have you faced in attracting investment toward your PatOP?

    • says

      What about the PatOP V-4 at ?

      (the animation is stereoscopic. If you want help to see stereoscopically go to ; otherwise focus on the left – or on the right – image).

      This V-4 PatOP has four cylinders and eight pistons.
      It is even firing (it fires four times per crank rotation, as a four-stroke V-8).
      It is perfectly balanced (the inertia torque included).

      Manousos Pattakos

      • Alex says

        In this engine (as in the engine OPOC) are too large reciprocating the moving mass and therefore it can not develop high speed.

        • says

          An advantage of all Opposed Piston engines is that by two short stroke opposed pistons (64mm stroke in the PatOP prototype) it is formed a long (64+64=128mm) and efficient (because of the small “surface to volume” ratio) combustion chamber (in the PatOP the combustion cylinder is 128mm long with 79.5mm bore).

          A conventional four-stroke engine having 128mm stroke and 79.5mm bore (i.e. same capacity and same “surface to volume” ratio) needs a long and heavy connecting rod (some 200mm center to center distance) heavily loaded in bending (the crankshaft needs also be larger – it has double “crank arm” – and heavier).

          While the strong “column” load carried by the long connecting rod of the conventional tends to bend it, the strong “tension” load applied on the short connecting rod of the PatOP tends to straiten it.

          Besides the revs-square, the inertia acceleration increases also with the piston stroke. The inertia acceleration on the piston of a conventional having 128mm stroke and running at 6000rpm (mean piston speed 25.6m/sec, i.e. more than most racing engines can reach) is double than the inertia acceleration at the same 6000rpm on the piston of the PatOP having 64+64=128mm stroke (mean piston speed only 12.8m/sec).

          For each combustion, each piston (with its piston rings) of the PatOP “travels” for 128mm (the two opposed pistons “cover” 256mm in total), while for each combustion in the above conventional four stroke, the piston (and piston rings) “travels” for 512mm at double speed (the friction increases with piston speed square or close to it).

          The combustion loads are way heavier than the inertia loads even at the rev limit, which is set by the time necessary to efficiently burn the Diesel fuel.
          The red-line is neither limited by the inertia of the moving parts, nor by the mean piston speed.

          For the V-4 PatOP: locating the turbocharger and all the intake and exhaust pipes into the Vee, the compactness becomes even better.

          Manousos Pattakos

        • Paulinator says

          If this engine doubles its power density by doubling rpm, then the pistons will be pulling what? 3500 ft per minute? And those long skinny skinny connecting rods and massive outer pistons will be experiencing 12000 force reversals every 60 seconds. A slender column is strong when its straight. bend it a little bit and it buckles. The “big” ends of those rods will be whipping around the crank throws at violent speeds. Do you think they might flex? Unless those rods are made of some unearthly material that hasen`t been discovered yet (with a Young`s Modulus of 14 billion), I will predict every prototype built as depicted by these STILL images and ANIMATIONS has come to a very noisy and sudden stop. I don`t know what they ran for 500 hours, but I hope the SEC investigates it.

      • Arion says

        Some questions on the PatOP V4:

        1. Crankshaft main journal areas (I count three) appear to be of minimal width and diameter. Are these judged to be sufficient given the engine’s balance?

        2. Judging from cylinder spacing, possibly increasing main journal sizes, and expecting that intake and exhaust ducting would extend around to the sides of cylinders as well as to their front and back, engine width would seem much greater than a conventional V4. How would these affect overall engine size and weight? Is specific power sufficient to avoid going wider and heavier than a conventional V4?

        3. The scavenge pistons appear to have disappeared in favour of counterbalance cubes? Or, are the scavenge pistons not shown? Would such pistons interfere with one another using present connecting rod lengths? Or, is the design dependent on turbo-charging or super-charging?

        • says

          1. The main journals remain constantly unloaded during operation. Each two opposed pistons share the same combustion chamber; this way every moment the force applied on the one piston is equal and opposite to the force applied on the opposite piston; and their connecting rods stay permanently parallel to each other.
          These make constantly zero the total force applied on the crankshaft by the combustion; they also make permanently zero the total inertia force applied on the crankshaft (for equal masses of the two opposed piston assemblies).
          Even for the single cylinder basic module of the PatOP the crankshaft main bearings are unloaded.
          Theoretically, if you remove the two main bearings of the crank of the PatOP single cylinder basic module, you can keep by your hand (by a pair of roller bearings, for instance) the crankshaft at its place with the engine running.

          2. The V-4 PatOP is wider than a V-4 and narrower than a V-8. Its balance, smoothness etc fit to a conventional four-stroke V-8. For the specific power: the 635cc single cylinder prototype weighs – without the flywheel – 20 Kg and it is a prototype. Reasonably a 2500cc V-4 PatOP will weigh way less than 80 Kg and will provide way more power than a 5000cc V-8 four stroke Diesel.

          3. The V-4 PatOP animation is deliberately not “finished”. It can use volumetric scavenging pumps, like the 1st PatOP prototype (they can move without interfering with one another). Alternatively it can use turbocharger(s). Yet for motorcycles and small-medium cars the single cylinder PatOP seems more than adequate.

          Manolis Pattakos

  17. Paulinator says

    These guys aren`t in the engine business…they`re in the engine development business. And the development path leads right into a granite wall…so why hurry as long as there are investors who are willing to sniff the vapour and buck up.

    • Loopy says

      I’m sure there’s an element of truth to that. Otherwise, why else could we be stuck in a world where nearly every auto-mobile IC engine on the planet is basically a 100 year old Otto/Diesel cycle clunker, albeit with a few 3rd-party add-ons?

      Nonetheless, I have a strong suspicion that in the next few years there will be strong competitive pressure from Asia, particularly China and maybe India, and they will start spitting out new designs at a pace that will really shake up the industry. Why do I suspect this?

      1) Because it has happened before. Apparently Europe used to have dozens of motorcycle manufacturers, but most of them weren’t able to compete when Japan’s big 4: Honda, Suzuki, Kawasaki, and Yamaha gradually improved and started packing more cylinders and higher RPM into a smaller package.

      2) It’s already starting to happen. With China already starting to export “Great Wall” cars to Australia, it is only a matter of time before their quality improves and they start asserting themselves with innovations.

      It’s like watching a train wreck about to unfold, and I don’t know whether to laugh or cry. After all, from the outside “the engine business” looks like a cosy oligopoly that thinks the word RISK is an expletive (why are big old companies always like that?). If legislation didn’t force them to, they would never get any R&D done.

      Anyway, the OPOC looks nice, though I’m not sure it will be quite as balanced as they claim when they factor in the forces exerted by the burning fuel, especially when accelerating. But the PatOP looks awesome. There’s got to be some way to get new designs to market, without relying on a 1-in-a-million chance that a billionaire will like your idea.

  18. spectator says

    Mmmm…. wikipedia tells me these were invented circa 1900 – future tech? not so sure about that. If it makes TD more efficient, I’m all for it.

  19. Loopy says

    Manousos, I see a lot of cool things in your developments!

    A few questions: could graphite piston rings be the answer to the old concerns about 2-strokes where oil contaminates the exhaust gases? Or does graphite have other issues or special requirements?

    I think I like the turbo charging option better than the scavenging pump. The scavenging pump looks like it has a fixed volume of air with which to flush the cylinder, whereas the air flow characteristics will probably change at different RPM. The brute force suction/pumping of turbos might be inelegant, but a turbo + electric motor-generator would allow energy recovery and reduced muffler requirements.

    I also like the idea of using crank-free cam operation, mainly because of the possibility of “shaping” cylinder expansion rates to optimise efficiency. Any chance of a “PatOP-GRECO 1″ or “OPRE-GRECO 2″ ?


    • says

      Graphite rings:
      Because of the crosshead pistons of OPRE and PatOP the piston slap is minimal to eliminated, which gives the graphite rings more chances to survive, in my thinking.
      The same thing, i.e. the fact that the combustion pistons do not touch the bore/cylinder gives a further possibility (with graphite or with conventional rings): the tapered liner. Instead of the conventional cylindrical liner, a tapered/conical (towards the combustion dead center) liner, so the rings get less compressed as the pistons move outwards and the pressure drops, so that as the rings reach the ports the rings may become slack and even not touch the ports at all. It not only reduces the ring friction (away from the combustion area where the sealing is useless) but also avoids the oil clung on the rings being deposited on the ports and their bridges, a good gain in friction, in oil consumption, in rings and liner longevity … seems reasonable.
      However, if there is one two-stroke valve-less with conventional-rings engine that minimizes the lubricant consumption this is the PaTOP / OPRE. The graphite rings are future options.

      Has its own problem: both the turbine and the compressor need to be tuned with the engine which has been attained only in a narrow band of revs and loads with the top sophisticated variable geometry rotors and casings.
      With the volumetric pump, which can be of the optimum size, there is no need of any piping except the gallery around the cylinder of the pump, the simplicity is maximal and the weight minimal. The best supercharging known is that of VW with the turbo in line with the supercharger.
      For a big V-4 PatOP the turbocharging (electrical or not) is a reasonable option.
      For a single cylinder PatOP (for small/medium cars, motorcycles etc) to add complexity / cost and to sacrifice the low-end torque is also an option.

      “Shaping” cylinder expansion rates to optimize efficiency:
      Is it not the first thing that OPRE and PatOP certainly do?
      Take a look at
      and at
      and especially at the GIF animation at
      Take also a look at the combustion pistons: the air is squeezed into the bowl and remain trapped there until the combustion completes i.e. more constant volume combustion.
      To substitute the fully conventional and tested for centuries crank to con-rod to piston mechanism of OPRE / PatOP by an unconventional and untested cam-drive mechanism (at ) is also an option. Do you want to try it? It takes much more; only someone of the size of Shaeffler-INA could possibly afford it.

      Manousos Pattakos

      • Loopy says

        Cam drive does look very appealing in theory and there’s an Australian group – Revetec who are attempting it and claim they can get very good efficiency from it. But on second thoughts, my concerns about it are:
        1) The entire force from the engine is concentrated on point loads on the exterior surface of the bearings (compared to the broad hemispherical loads in con-rod bearings).
        2) The bearings “roll” on a lubricated surface, so their performance is unpredictable. If a bearing jams, it might not be noticed until one of the cams has worn unevenly. Maybe this can be avoided by relying on high friction between the surfaces, but that would probably increase wear anyway. Alternatively, a Wankel-style cushion that slides on the cam?

        The disadvantage I see with the 6000 max RPM is that it also increases the minimum RPM. But you could still market this as a net benefit: 1) people are accustomed to higher revving cars 2) automatic gearboxes are apparently harder to make for low-revving diesels 3) gearbox might be lighter.

        Thanks for showing us your work. Whatever you do, don’t give up!

  20. says

    Loopy : “ Disadvantage I see with 6000 max RPM is that it also increases the minimum RPM …”

    Take a look at and : as you see, the top power-density at high revs (naturally breathing) does not necessarily increase the minimum RPM.

    In Engine-Expo-International, June 2009, Stuttgart Germany, I gave to the Heads of VW/Audi, Daimler, BMW, Porsche, Toyota, Aston Martin, Subaru…(who came to collect the Engine-of-the-Year awards) a paper writing “I have here, in pattakon booth, a Honda civic VTEC modified to PattakonVVA-roller that makes 250 bhp AND idles at 330 rpm and most of the time I use the fifth gear to drive it downtown because it has a flat torque from 900 to 9000 rpm”

    I told the Aston Martin Engineers that their 0-77 Supercar (for which they were so proud to present there) by the correct VVA on its cylinder-heads can turn to a twice as fuel efficient/green and half as gas-guzzler. Their excuse? “But we are going to make only 77 such cars…”

    The Ducati, that regularly humiliates the Big-Three from Japan in the MotoGP, can keep winning and become also rider-friendly by replacing the old single-mode Desmodromic by the Fully Variable Desmodromic DVVA at .
    A four-in-line 1000 cc / 180 bhp motorcycle engine capable of delivering 10 Kp*m torque from below 1000 rpm, idling at 300 rpm, with efficient and smoother running at partial loads / low-medium revs, sounds as the perfect downsizing. All it needs is a DVVA.”

    Back to the two-stroke rev range:
    By the integrated volumetric piston-type small-dead-volume scavenging-pump of the PatOP (the big-diameter lower-end of the intake piston assembly) the efficient rev range is wider than the four-stroke engines. Either at low or at high revs, the scavenging pump displaces positively a more-or-less constant quantity of air to the space around the intake ports.
    This has nothing to do with the conventional turbo-chargers or with the centrifugal pumps used in the two-stroke Junkers airplane engines (with their peaky torque they were used mostly in cargo airplanes).
    Theoretically, for each rotation of the crankshaft of the 635cc PatOP prototype, the scavenging piston displaces positively 850cc of air (130 bore, 64 stroke) to the space around the intake ports (the pressure inside the scavenging cylinder is automatically adjusted).

    The 6000 max RPM (the 35-40% longer dwell of the piston of the PatOP around the Combustion Dead Center allows efficient high-revving direct injection Diesels) does not increase the minimum RPM: the positive scavenging enables flat torque curve from low revs. And if, at low revs, the additional time is more than necessary, retarding the injection for a few degrees is all it takes.
    I wonder if my saying “the dwell of the pistons of the OPRE and the PatOP engines is 20% longer than the dwell of the OPOC and 40% longer than the dwell of the conventional pistons” is understood. Think the case somebody grants you 40% or 20% more years (of youth).

    Manousos Pattakos

  21. says

    Reply to Paulinator’s post of February 26, 2011, 4:52pm.

    Sorry but I missed your post (it would be easier for the readers to find the most recent post at the bottom).

    The PatOP and OPRE direct injection Diesel engines can burn the fuel at 6000 rpm as efficiently as the state-of-the-art direct injection Diesels at 4500 rpm (because of the additional time the piston dwells at the Combustion Dead Center; see the animation )

    The complete stroke of the PatOP is 64+64=128mm.
    Because of the short stroke (64mm) of each opposed piston, the acceleration (as well as the mean piston speed) is low.
    At 6500 rpm rev limit (13.8 m/sec or 2730 ft per minute mean piston speed), the maximum load on the kinematic mechanism from the combustion is about double as compared to the maximum inertia load.
    And the maximum acceleration happens when the opposed pistons are at the maximum distance from each other (BDC).
    And the maximum inertia force from the piston assembly is equally divided to the two connecting rods, loading them in tension.
    The force from the combustion on the piston crown is also divided equally to the two connecting rods that are loaded, again, in tension.
    I.e. even if you start the engine with slightly bend connecting rods, the combustion and inertia loads will straighten them.

    The center to center distance of the connecting rods of the PatOP is 115mm for 64mm piston stroke. On the other hand, you write about “long” connecting rods. Are you sure you talk about the PatOP (at ) engine, or are you talking about the OPOC of EcoMotors?

    The “skinny – skinny” (as you call them) connecting rods are more than sufficient for the kind of the loads they carry.

    By the way, open the GIF animation of the Commer TS engine at (or better open the controllable windows exe animation of the Commer TS at ) and compare the tension loads of the “skinny” connecting rods of the PatOP to the heavy bending loads of the two blue massive rocker arms of the Commer TS.

    Manousos Pattakos.

    • Loopy says

      Hi Manousos,
      How is the project coming along? I can only speak for myself, but it seemed like there was a lot of curiosity when you presented your PatOP engine as an alternative which, unlike the OPOC, actually has a working prototype.

      You might not want to hear this, but there are some important things that companies like Ecomotors do better than you. For example: marketing. I if were you, I would take the best parts from websites like and and replace the content. Just imagine…

      “Pattakon International(TM)”
      Some tabs:
      Home | Development | About Us | Investment Info | News | Careers | Contact

      On the left: a youtube video of you recommending your own product. If you don’t look old enough, just make your grandfather the CEO and ask him to do it.

      Home —> Basic introduction about what it is, and how the amazing developments allow high efficiency and low emissions. But save the details for later. Add a computer-generated animation that looks as detailed and complicated as possible, then add a caption explaining that it is 40% simpler and reduces the number of parts by 25% compared to the competition.

      Development —> The detailed information you already have.

      About Us —> Employ your family and friends, and add up the number of years experience they have. If your core leadership team has less than the 230 years that Ecomotors have, add more friends.

      Investment Info —> invite people to give you money.

      News —> status updates, etc.

      Careers —> makes your company sound really big, even if you don’t have any positions available at the moment.

      And on the home page, people can “read more” about the good life in Greece!

      • says

        Loopy, thanks.

        On the other hand, the big words and the big numbers fuel the threads around the web and the traffic of the pattakon site “hits” red.

        Manousos Pattakos