- Achates Power has developed an opposed-piston engine that could potentially save the diesel engine by offering a more efficient and cost-effective solution.
- The 3-cylinder engine delivers excellent performance with 400 horsepower and 1,674 lb-ft of torque and has the potential for impressive fuel economy figures.
- The environmental benefits of the Achates Power engine are significant: CO2 emissions are reduced by 7% and NOx emissions by 96% compared to traditional diesel engines. Retrofitting existing trucks with this engine is a more feasible and economical solution than replacing them with electric trucks.
Governments around the world are cracking down on vehicle emissions, and while that’s certainly not a bad thing, it raises many questions about the future of the trucking industry. How long can diesel trucks last before stricter government regulations phase them out? Is electricity the answer, or is something else brewing?
Privately held company Achates Power thinks they may have the answer, and truckers can be glad it’s still a diesel application. Tested in typical pickup, the results really look promising. In an effort to rejuvenate old technology for the modern world, Achates Power developed an opposed piston engine; Here’s everything you need to know about it, including how it could save your diesel engine.
Information has been collected from many reputable sources, including the Achates Power YouTube channel and website, in order to bring you these details about their opposed piston 3-cylinder engine.
This is how an opposed piston engine works
The video above shows very clearly how an opposed piston engine works and is a great demonstration of how efficient this design is. The opposed-piston design eliminates many of the components required in a typical internal combustion engine, saving manufacturing costs while potentially increasing reliability.
The basic design is that two pistons share a cylinder chamber and fire toward each other in a vertical format.. At the point where they almost meet in the middle, the ignition pulls them back. A set of crankshafts are connected at the other end and connected through a set of gears that provide power to the transmission. With this design, there is no need for a cylinder head, valves or camshafts – the cylinder head in particular is an area where a lot of energy is wasted, creating inefficiencies in traditional internal combustion systems.
This is different from an opposed engine, where the cylinders are positioned against each other horizontally rather than vertically.
Achates Power 3-cylinder engine provides excellent performance
Although the main focus of this engine is on creating a cleaner and more energy efficient vehicle for diesel trucks, rather than outright performance, the latter is still important. There’s no doubt that diesel trucks work hard, and truckers won’t be happy to hear if they have to struggle on hills and settle for underpowered engines, even if it’s in the name of cleaner emissions.
The team behind Achates Power knows this and as a result have made sure their 3 cylinder 6 piston engine delivers what it needs. As the small table below proves, there is plenty of power produced and the torque figure is adequate for even the most demanding applications.
Performance characteristics of the 10.6-liter opposed-piston diesel engine Achates Power
A turning point
While the MPG figures for the Class 8 10.6L 3-cylinder engine are currently unknown, due to the lack of real-world testing, we have verified figures from another Achates Power engine. The firm developed a 2.7-liter engine of similar design that was extensively tested in the Ford F-150, known as a light-duty opposed-piston engine. Along with delivering 270 horsepower and 479 lb-ft of torque, the engine achieved an impressive 37 mpg; that’s 12% above the 2025 CAFE (Corporate Average Fuel Economy) target of 33 MPG.
Compare that to the current 3.0-litre diesel offered by Ford, and not only does it return significantly improved fuel economy, but it generates 20 more horsepower, and crucially more than 39 lb-ft more torque. The efficiency of opposed-piston engines is again impressive.
The environmental benefits of this engine could revolutionize trucking
Here are the headline numbers; Achates Power claims it has already experienced a seven percent reduction in CO2 emissions during testing, in addition to a significant 96 percent reduction in NOx emissions compared to a conventional diesel truck engine. The company published a much more detailed analysis of its findingsbut in short, Achates Power is confident in its own design that even the most stringent emission standards around the world can be met with this design.
So how does this revolutionize the trucking industry – wouldn’t it be greener to use electric trucks like the Tesla semi? While the aforementioned Tesla and other electric vehicles like it hold a lot of promise and will undoubtedly help reduce emissions in the industry, many truck drivers feel that they simply aren’t the answer, and here’s why.
The obvious first problem is range; trucks are expected to travel hundreds of miles every day. Thanks to the large fuel tanks, they can do this without stopping and wasting time on a regular basis, but this would not be possible now, as the range is reduced to only hundreds of miles when relying on electric power. This brings us to the second major issue, which is the infrastructure needed to support a nation of electric truck drivers.
Have you ever seen an emergency truck stop? Imagine the chaos of trucks queuing for hours to “fill up” and we doubt the huge long-haul batteries will charge too quickly either. Finally, the number of diesel trucks on the road is staggering, so the cost of replacing them within a reasonable timeframe is completely uneconomical. However, Achates Power’s engine would require much less work to retrofit existing trucks, thus negating the environmental and financial costs of building new trucks. This is a win-win option.
That is why opposed-piston engines are rarely used
Although the design is over a century old, there are several main reasons why opposed piston engines are not widely used. Here’s a quick breakdown of those reasons and whether or not they apply to Achates Power Design.
- The first issue is simple, space. Naturally, opposed-piston engines are quite high, which limits the possibilities of their application. While this poses a problem for cars, Achates Power is not worried about Class 8 trucks.
- Two-stroke designs like this are usually terrible for oil consumption, but then again, modern technology means Achates Power has the confidence to say their design has no worse oil consumption than a typical four-stroke internal combustion engine.
- The required gear can be quite heavy and complex as it has to be connected to two pistons in each cylinder. While this may seem overly complicated compared to a more traditional design, savings are made elsewhere, such as the lack of cylinder head requirements.