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According the drive tests performed by the auto-journalists and published in the Internet, the Mazda SkyActiv-X does work in practice. The problem of the SkyActive-X is its over-complexity (and cost). In comparison, the PatBam HCCI (more at ) provides control over the HCCI combustion, being by far simpler and cheaper. Thanks Manolis Pattakos
Hello. At a different rotary engine is presented with working surface (whereon the seals abut and slide) not cylindrical (as in the Wankel and in the LiquidPiston) but 3D-curved, enabling a better sealing and a higher efficiency. Manousos Pattakos
Take a look at the PatATi, a simple two-stroke (only three moving parts, no reed valves, no rotary valves) with asymmetric transfer and asymmetric intake, at Thanks
The VW 1.4-litre TSI ACT (cylinder deactivation system) was voted at the Engine Expo International as the “Best New Engine” of 2013. Quote from the Internet (test drive of the small VW POLO 1.4 TSI ACT): “Temporary shutoff of the second and third cylinders – in conjunction with an economical style of driving – reduces fuel consumption by over 0.5 liters per 100 kilometers. Even with two cylinders the excellently balanced 1.4 TSI runs just as quietly and with low vibration as with four active combustion chambers.” The consumption reduction comes from the fact that the two active cylinders of VW operate at substantially heavier load when the two others are deactivated. At light loads the efficiency of the spark ignition engine drops a lot. The bad thing with VW’s solution is that the deactivated cylinders still have pistons and piston rings reciprocating inside them consuming energy as friction. When the VW ACT engine operates at partial loads, it pays its vibration-free quality / smoothness / quietness with the friction (mechanical energy loss) of moving a pair of “useless” pistons / sets of piston rings. If the two deactivated pistons could be removed, the reduction of the fuel consumption would double (?), as well as the vibrations and the noise. Unless I am wrong, the two middle cylinders of VW ACT engine are the only ones that are deactivated. What is the long-term effect on the engine after, say, 100.000 miles? Is it clever to operate at heavy load the two “worn” cylinders and leave the actually “unused” pair of cylinders idle? Does it reduce the TBO? By the way, the “cylinder deactivation” in Diesels is not so good because the friction of the idle cylinders is bigger and because the thermal efficiency of the Diesels at partial loads is not bad. What the VW Passat TSI ACT proves is that a single combustion per crankshaft rotation is acceptable / adequate for small and medium size cars (a four-stroke with two active cylinders has one combustion per each rotation of the crankshaft). The same is proved by the four-stroke two-cylinder TwinAir engine of FIAT / Chrysler used in several small / medium size cars like the New Alfa Romeo Mito TwinAir. In this case (true twin cylinder engine) the absence of another pair of “driven / inactive / power consuming” cylinders reduces the friction and increases the mileage (as well as the inertia vibrations and the noise). A well balanced internal combustion engine having one combustion (i.e. one power pulse) per crankshaft rotation seems as the future for “green” small-medium size cars. With the cylinder-liner rid of intake and exhaust ports, the single-cylinder two-stroke PatPortLess engine at combines among others: true "four-stroke" lubrication, true "four-stroke" specific lube consumption, true "four-stroke" scuffing resistance, true “four-stroke” emissions, and one combustion per crankshaft rotation, i.e. as much as the VW Passat 1.4 TSI ACT (at partial loads) and as much as the Alfa Romeo Mito TwinAir. As for the smoothness / “vibration-free” quality of the single-cylinder PatPortLess, it is comparable to that of the four-in-line of VW Passat 1.4 TSI ACT and it is substantially better than that of the two-cylinder TwinAir of FIAT / Alfa Romeo (last GIF animation in the abovementioned web page). So, would you consider buying a small - medium size car having a single cylinder engine? Thanks Manolis Pattakos
I see plenty of funds. I also see "heavy" new names added to the advisory board of Achates Power. Did the new members of the advisory board see what the PatMar engine at can do? The UK patent for the PatMar engine has been granted and is in force. The US patent for the PatMar engine has been approved. The PatMar engine is a 2-stroke with TRUE 4-stroke lubrication and TRUE 4-stroke scuffing resistance. Isn't it? If they prefer their "like 4-stroke lubrication", they can take a look at the OPRE engine at and at the PatOP engine at . Thank you Manousos Pattakos
Compare the OPOC of Bill Gates / Khosla / Braemar / EcoMotors with the PatOP opposed piston engine at The PatOP basic unit is: smaller and shorter, more vibration free, simpler with some 50% fewer parts. The PatOP has way lower specific lube consumption ("like" 4-stroke lubrication) and provides some 20% additional time for the injection and the efficient combustion of the fuel. The big issue EcoMotors has still to address? The lubrication of their OPOC engine. Otherwise the OPOC will be limited to special applications. As for EcoMotors' "variable capacity", there are better, cheaper and more reliable ways to realize the same, as explained at Thanks Manousos Pattakos
With famous investors/supporters, with great companies to team with, with funds of many millions of dollars, and with several years of experimental work, EcoMotors finally did it: “published an animation”. Maybe it’s time for Bill Gates to rethink the case. EcoMotors presents their “dual-module” variable capacity arrangement as a wonder. The idea: OPOC module (a pair of opposed cylinders, a crankshaft and four pistons) is rid of unbalanced inertia forces and is well balanced as regards its inertia moments (the inertia torques is another story). So, they connect conventionally the first OPOC module to the gearbox. Then they put additional OPOC modules in a series, with special clutches (controlled electronically) between neighboring crankshafts. The first OPOC module operates permanently. The second module is engaged at medium to heavy loads (for instance during an acceleration, at an uphill etc). The third module (if any) is engaged at heavy loads (say at top speed, at heavy acceleration etc). One problem: The engagement / disengagement of the cylinders is in pairs. Another problem: The first OPOC module operates permanently at medium – heavy load. From time to time its crankshaft transfers to the gearbox the torque of the rest modules. In the case of a serious problem in the first OPOC basic module, the complete engine stalls and the vehicle stops, even if the second, the third etc OPOC modules are at perfect condition. As compared to a similar OPOC engine having a single crankshaft serving all the cylinders (non modular architecture), the “mean time between failures” shortens because the first module operates permanently at heavy load and because it undergoes additional loads during the engagement of the rest modules. To sacrifice the reliability of a truck / car for the sake of a better fuel consumption, sounds “not so great idea”; especially when there are alternatives that improve both, reliability and efficiency. Compare EcoMotors’ “dual-module” architecture to the way simpler architecture shown at , wherein the cylinders disengage one by one, wherein there is no need for special clutches, wherein the control is simple, wherein the reliability of the engine is way improved: if the one module fails, the vehicle continuous with the other module “for ever”. Here the “mean time between failures” extends as compared to the “mean time between failures” of each one of the engines. Consider the case of a sport car having a powerful V-8 engine at the one side of the primary shaft of its gearbox, and a small green engine (like the single cylinder full balanced PatOP, or like the Fiat 500 TwinAir) at the other end of gearbox primary shaft. Compare this solution to the new sport hybrid cars the sport-car makers launch in their effort to comply with the present and future emission regulations. Manousos Pattakos
As for the piston skirt, it does not touch the cylinder liner (there is a gap – as much as you like - between the piston skirt and the cylinder liner); the crosshead slippers sliding on the crosshead guides take the thrust loads. The piston skirt is there only to separate the space underside the piston from the crankcase, not to take thrust loads. And as in the conventional crosshead 2-stoke marine engines (take a look at the bronze bands on the RTA84 2-stroke piston at ) a short zone below the rings keeps the piston at the center of the cylinder. Similarly the shell/“pants” inside the piston is not in touch with the piston skirt (there is a gap between them). Only the sealing rings are in touch with the inside surface of the piston skirt. Regarding the crosshead contact area, take a look at to see its size in comparison to the wrist pin. The PatMar does not decrease the size of the crosshead. So, the PatMar neither increases the sealing members (relative to the conventional 2-stroke crosshead low speed marine engine), nor increases the contact surface between the piston and the cylinder liner, nor the relative friction. Manousos Pattakos
“I see 2 issues with the PatMar: 1) the single . . . with the cylinder wall.” If there is an issue with the central valve and the heat convention, you can always put more valves on the piston crown. Take a look at the first PatPortLess engine at with the 4 intake valves. On the other hand there is no such issue: the bottom of the cylinder liner is way coolers than the top of the cylinder liner near the cylinder head (think for how long the bottom of the cylinder liner “sees” hot gas. Regarding the swirl: The supports (holders) of the valve guide of the central valve can provide as much swirl as desirable (think of them as stationary wings). However the swirl has its own drawbacks. Regarding the rings and the friction: The friction of the rings between the inner surface of the piston and the "pants waist" is more or less the friction of the sealing rings between the piston rod and the casing of the conventional low speed 2-stroke crosshead engine. Take a look at the “state-of-the-art” drawing at the .
A big marine engine needs not to stop in order to change a filter. The lubrication system comprises pumps, filters, coolers, centrifugal separators (LAVAL) etc. The current medium speed Diesel engine (for marine applications and for power plants) can operate continuously for two - three years. You write: “The higher oil consumption of a ported 2-stroker is not a big issue if kept to a practical level. “ EcoMotors has applied for patents for special oil rings that “reduce” the lubricant consumption of their OPOC engine. This is an important issue. For aviation applications the excessive lubricant consumption could be allowable. But for cars and trucks the lubricant consumption must be low. It is not the lubricant and its cost. It is the combustion that worsens and the emissions that increase. They cooperate with Navistar for almost a year, Bill Gates supports them for long, but they have no engines to show or sell.
Roger Pham thanks for the opportunity me to explain how things are. The big 4-stroke medium speed marine engines run on the same heavy fuel as the crosshead low-speed 2-stroke marine engines. Advantages of the heavy marine fuels are their lower price and their availability. The functions of the lubricating oil are (from a presentation of Wartsila) : Lubrication and sealing, Cooling, Cleanliness and Corrosion protection: the lubricant is characterized by its “base number” (mg KOH/g). The alkaline of the lubricant interacts with the sulphur acid protecting the parts of the engine. For high sulphur fuels, lubricants with higher “base number” are used.
. . . By the way: the giant 2-stroke low-speed crosshead engines run on 160 gr/KWh (60% of full load). Some of them use a turbocompounding at their exhaust for a little better BSFC (158 gr/KWh). The crankshaft drives directly the propeller without gears (additional cost addittional power loss) between them. Wartsila makes 2-stroke crosshead and 4-stroke medium speed. They know better than you and me. And they try to combine the advantages of both in one. Manousos Pattakos
. . . All the four valves of the cylinder head become exhaust valves. A shorter connecting rod replaces the original long one. The engine architecture turns to crosshead. The height of the engine remains the original. The cylinder liner is rid of thrust loads (and deformation). The piston runs as cool as necessary. The lubrication is true four stroke. The combustion bowl and the injection are actually identical to the original ones. The engine peak power is double. Now compare the energy consumed as friction per crank rotation in the original and in the modified engine. Is the additional friction by the different valve train, and by the additional oil ring in the space underside the piston, so big to reduce the overall brake thermal efficiency?
Peter XX A way to approach the operation of the PatMar is to start from a big crosshead marine engines. Another way is to see what it takes to modify an existing 4-stroke to PatMar, and how this modification affects the friction, the fuel consumption and the peak power. At the bottom of the page you can see what it needs the Wartsila 64, the top 4-stroke medium speed engine today (900mm stroke, 640mm bore, 2000KW/cylinder at 333 rpm) to turn to 2-stroke crosshead.
@Peter_XX At your last sentence you accept the claim that Achates 2-stroke is, at least, as efficient as the state-of –the-art 4-Stroke. Suppose also that the claimed 0.1% oil-fuel consumption is achievable too. Could you write an advantage of the OPOC engine or the Achates engine over the PatOP and the OPRE engines, just one? Let me write an advantage of the OPRE engine over any other known engine: OPRE is going to be the prime mover of the Portable Flyer (see the videos) This is because it is getting less than 20 Kp (45 pounds), but mainly because it is as perfectly balanced as to cause zero fatigue to the pilot hands and body. Because it is free of any inertia and any combustion vibration, ANY. There is a company in New Zealand making the Jet-Pack; compare them to what I am talking about. But for road transport, the portless pattakon engines might pass the regulations more easily, for the time being. Manousos Pattakos
Peter XX thanks for you analysis. For a calculation, any calculation, you need a lot of assumptions. Are you sure for yours? Reasonable question: according your calculations, how is it possible the Achates engine to run on a brake thermal efficiency of 45.1% (192gr/KWh)? We talk for an experimental engine made on a limited budget, without great experience in this field. Reasonably this 45.1% will increase over the 46,5% of the best state-of-the-art 4-stroke Diesels of this size made by the big engine makers (and based on experience of many decades). The Junkers Jumo 205D (105 bore, 2x160 stroke) had, at 2400 rpm and at full load, a BSFC of 216 gr/KWh (40% brake thermal efficiency), more than 70 years ago. This 40% is not the optimum thermal efficiency; it is the thermal efficiency at full load. In case your calculations do confirm the 45.1% of Achates, can you please repeat the calculations for the PatOP engine? And because you don’t like the piston scavenging pumps, use an electric turbocompounding for the scavenging of the PatOP. The Achates architecture (just like the Commer TS architecture, a version of which seems to be one of the future concepts of Achates Power, according their patents) adds internal loads: compare the combustion and the inertia force on the piston to the resulting loads on the crank pins and on the main crankshaft journals of the two side crankshafts. Then think what it the total force on the two main journals of the PatOP crankshaft: zero. Theoretically you can hold the PatOP crankshaft by your hands during full load operation / high revs. The combustion and inertia force on each piston of the PatOP is equally shared between the two connecting rods. The trust loads are taken as in the 4-stroke engines. Then see the videos of the single cylinder PatOP prototype running on Diesel fuel, standing free on a desk, to see the “vibration free”. Manousos Pattakos
To Roger Pham Thank you. If the investors of EcoMotors, Achates, Pinacle etc read this forum, they may think: "Unless our patents are ahead of his, we are working for pattakon." Manousos Pattakos
To PeterXX In the same journal they explain how they achieve to reduce by US170,000$ per year the operational cost of a 12-cylinder Wartsila RTA96 (63 MW) container vessel engine: they substituted the CLU3 (cylinder lubrication unit) by the new CLU4. The lube specific consumption drops from 1.2 gr/KWh to 0.8gr/KWh. Wartsila knows better than anyone the advantages and disadvantages of the big marine diesel engines and is searching for ways to combine the low lube consumption and the better scuffing resistance of the marine 4-stroke with the direct propeller drive of the 2-stroke crosshead long-stroke engines (wherein the stroke is some 3 to 5 times longer than the bore). This is what the PatMar engine achieves: to combine the advantages of the long-stroke crosshead 2-stroke engine with those of the 4-stroke. And it is not only for marine applications. Imagine a heavy truck powered by a four-in-line PatMar having 90mm bore and 400mm stroke (10 lit), making its peak power at 1000 rpm and its peak torque at 600 rpm. During the combustion, the volume to surface ratio is better than anything. Etc Manousos Pattakos
To Peter XX Wartsila / Sulzer is the manufacturer of the giant two stroke low speed marine engines. Wartsila is also the manufacturer of the top 4-stroke marine engine with 2,000KW/cylinder (Wartsila 64). Quote from Wartsila's technical journal, 02, 2010: "Some years ago, an Inner Lubrication System concept was studied at Wärtsilä, and a prototype was developed and tested with positive results. Based on this, and on some good results from applying an oil scraper ring in the piston ring pack on a Wärtsilä RTA96C engine, where an oil supply from the piston side might be advantageous, it has been decided to take this concept up again and develop it to a commercially applicable level. A slightly more ambitious idea is to apply the four-stroke trunk piston engine cylinder lubrication concept to the twostroke crosshead engine, i.e. to “overlubricate” the cylinder liner, apply an oil scraper ring, and then collect the surplus oil, clean it, and recycle it. This will of course be a radical change of concept, and whether or not it is viable remains to be demonstrated, but an outline exists and a patent is pending. The aim is to increase scuffing resistance and to achieve the same low specific oil consumption level as on the four-stroke trunk piston engines." Manousos Pattakos
To Peter XX The piston of the PatPortLess prototype comprises a steel crown with the ring grooves and the intake valve seat. The rest piston is aluminum. Thanks Manousos Pattakos
@ Peter_XX You write: “It seems as you have a serious problem in understanding electric turbocompounding. . . . in short, I could summarize: Under some driving conditions electricity must be supplied from the battery. Under other driving conditions, turbocompounding provides surplus electricity for battery charging. However, most important to note, is that the n e t energy contribution is positive” Thanks. However the electric turbocompounding is not necessarily related to the assistance of the engine breathing. Scavenging a two stroke by a "piston type" volumetric pump enables the direct response of the sport non-turbo 4-strokes. Besides, without back pressure the piston pushes the exhaust gas easier - consuming less energy - outside the cylinder. The electric turbocompounding, "a system that converts waste exhaust energy to shaft work, using a turbine, and couples it back to the engine, electrically" as John Deere explains, is always an option. For instance, if the electric generator of the car can operate as an electric motor too (there are such electric generators), the energy from the electric turbocompounding can be directly consumed there to assist the rotation of the crankshaft and the motion of the car (no need for a battery to store the energy). Compare this case to the electric turbocompounding that scavenges a 2-stroke engine. If the engine runs at some conditions for long, the battery is charged and then any energy generated by the electric turbocompounding is lost; if the engine runs at some other conditions for long, the battery is discharged and the scavenging is is not good. Etc. Manousos Pattakos
@ Peter_XX You are right saying that the problem in the 2-stroke engines is the transfer ports (provided the 2-stroke engine has transfer ports). The problem gets worse in case the cylinder liner receives the thrust loads from the connecting rod, because a thicker oil film is necessary. The thicker the film on the cylinder liner, the more lubricant “is blown into the cylinder, burns or escape with the exhaust”. This is the case for the Detroit Diesel with the intake ports on the lower side of the liner and the exhaust poppet valves on the cylinder head. The problem softens a lot in case the cylinder liner receives no thrust loads (crosshead architecture), which is the case for the Achates engine (and for the PatOP and OPRE engines of pattakon). The oil film on the cylinder liner is now quite thinner and prevents the metal-to-metal contact between the piston rings and the cylinder liner. The oil film between the compression rings and the cylinder liner is some 5 times thinner than the oil film between the typical piston skirt and the cylinder liner. This “dye” of lubricant remains on the cylinder liner above the piston rings. You are wrong thinking that all 2-stroke engines have transfer ports through which the lubricant is lost. Obviously you didn’t see the engines mentioned. Both the PatMar and the PatPortLess engines are 2-stroke uniflow engines rid of ports on the cylinder liner. So please take a better look and write again about the possibility of a 2-stroke to have lower lube consumption than the best 4-strokes. Manousos Pattakos