WARRENVILLE, Ill. — Navistar International has partnered with EcoMotors International to further develop a new engine design that the companies claim will revolutionize the diesel engine landscape.

Dubbed opoc (Opposed Piston-Opposed Cylinder), the engine is comprised of two opposing cylinders per module, with a crankshaft between them. Each cylinder has two pistons moving in opposite directions. The design eliminates the need for a cylinder head and valvetrain components found on conventional engines, saving weight and improving efficiency, according to the companies.

The key to the opoc design is its improved power density, company officials explained in a Feb. 22 conference call with media. The power density, they claim, is two to three times greater than that of conventional diesel engine designs, allowing for: lower weight; smaller size; lower material costs; improved fuel economy; and lower emissions.

Also key to the opoc is an electrically-controlled turbo, which: improves combustion efficiency to lower emissions; improves fuel economy; eliminates turbo lag; and improves drivability by producing more low-end torque.

An electrically controlled clutch is housed between two engine modules. When the second engine module’s power is not required, the clutch is disengaged, allowing the second engine to stop completely, leading to improved fuel economy and better performance from the primary module, the company claims. The perfectly balanced modules can be stacked to meet the power needs of the vehicle.

During a conference call, EcoMotors and Navistar officials said the new design is half the size and weight of a conventional turbo diesel engine, while boasting improved efficiency and best yet, will cost less than today’s commercial diesel engines.

The opoc, EcoMotors claims, has a very high power density of one horsepower per pound. Its simple design, the companies say, allows for 50% fewer parts than conventional diesel engines and it can be configured to run on all types of fuels, including diesel, natural gas, gasoline or even hydrogen. The concept has received financial backing from the likes of Bill Gates and Vinod Khosla, founder of Khosla Ventures.

“EcoMotors is proud to partner with Navistar to commercialize the revolutionary opoc engine,” announced Don Runkle, CEO of EcoMotors International. “For customers such as Navistar, this remarkable engine technology represents a competitive advantage that enables not only enhanced environmental sustainability, but also greater profitability. Our engineers are working to effectively rejuvenate the internal combustion engine for the 21^st century.”

“Our company has a long history of pushing the envelope to deliver state-of-the-art, customer-focused solutions and we see great promise in EcoMotors’ breakthrough engine design,” said Dan Ustian, chairman, president and CEO of Navistar.

Ultimately, opoc engines have the potential to reduce fuel consumption by 15%, officials explained. As far as applications are concerned, Eric Tech, president of the Navistar Engine Group, said “I think this is applicable in virtually anything you can conceive of.”

Prototypes are already being used today, officials said, with Navistar planning to roll the technology out in its smaller commercial vehicles within two to three years. In terms of displacement, a 250-hp prototype today has just 2.5 litres of displacement. Officials said the opoc is measured more in terms of horsepower per pound. But for sake of comparison, Ustian said a 13-litre engine would be comparable to a 5.2-litre opoc.

Because the opoc comes in a smaller package, it has the potential to radically change the way truck chassis are built and configured, officials said.

“One of the things we’re looking at is what modifications have to be made to the conventional mounting to take full advantage of this?” said Tech. The opoc, he pointed out, can ride lower in the chassis, affording manufacturers the luxury of improving visibility and aerodynamics while adding cargo space.

Navistar officials also said the opoc engine design also gives them the opportunity to continue to comply with emissions requirements without using selective catalytic reduction (SCR).

As far as the partnership goes, Navistar will be contributing its combustion technology expertise as well as its emissions know-how to take the concept to the next level of development. The two partners were evidently excited about the potential of the opoc. EcoMotors CEO Runkle noted the global engine market represents about 100 million engines per year, worth about $350 billion, “and in our humble opinion, we don’t see why they shouldn’t all be opocs.”

For more on how the technology works, check out the video here.