Issue: Jul 2010

EcoMotors Truck Engine


by Bob Brooks

EcoMotors, developer of a unique 2-cycle engine with two pistons per cylinder has indicated that it is concentrating its development work on a two module 300 hp, 600 ft lb torque diesel truck engine. EcoMotors had earlier indicated its first customer is an industrial engine firm in China. Priority interest as a truck engine now casts the technology in an entirely different light.

Speaking on a recent Detroit talk show, EcoMotors CEO Prof. Peter Hofbauer, inventor of the OPOC (opposed piston, opposed cylinder) engine, said that at less than half the size and weight vs. conventional diesels, coupled with exceptional fuel efficiency, the system has advantages for use in the large market for light trucks. (Animation of the engine can be seen at

Hofbauer explained that the inherent lower friction and thermal losses in the engine account for 15% fuel efficiency gain vs. conventional diesels, then an additional 35% gain is realized from complete shut down of one of the two engine modules via a clutch system at moderate and low load conditions. By contrast, vehicle piston engines with cylinder deactivation do not escape parasitic friction losses from operation of the “dead” cylinders.

Hofbaurer directed the effort at VW to adapt diesel technology to that firm’s engines and became interested at the time in the VW boxer engine in which he saw an opportunity to direct a significant portion the forces in the combustion chamber to another piston for useful work rather than to the static cylinder head. As a consequence, OPOC engine piston travel is cut in half permitting higher speed with consequent better power density as well as reduced friction and thermal loss. Usual 2-cycle engine emissions and poor fuel efficiency are avoided by the OPOC engine design (the World’s largest reciprocating piston engines, now well over 50,000 hp for marine use, are the 2-cycle type)

Hofbauer declined to name the auto industry firm it is working with on the 300 hp OPOC diesel truck engine project, but did say the engine will be available for inspection by the media next year. It has been learned independently, that EcoMotors is in contact with over a dozen potential automotive customers which can be expected to step up evaluation of the technology if testing of the initial 300 HP engine progresses favorably.

In fact, since EcoMotors has already successfully demonstrated the durability of one of its engine modules in 500 hour testing, this aspect adds to the incentive of interested parties to go forward. The 300 hp truck target is another indicator of the potential as it can lead to all manner of vehicle, stationary, marine, aircraft and other uses with single and multiple engine systems.

Adding dimension to the OPOC engine program is its development entirely with private funding including a recent infusion of $23.5 million from Bill Gates. EcoMotors primary financial support is provided by the highly successful Khosla Ventures firm which is also supporting advanced critical fuel combustion technology at Transonic Combustion. TSC has demonstrated the ability of gasoline fueled engines to duplicate diesel efficiency levels with insignificant emissions control needs. TSC system engines can also use virtually any mixture of gasoline, diesel fuel and alcohols due to its broad multi fuel capability.

Asked if EcoMotors is planning an IPO (initial public offering), Prof. Hofbauer said “we have no plans for an IPO... perhaps in the future”.

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