Aramco has unveiled a new hybrid powertrain designed to keep internal combustion engines relevant in a shifting automotive environment. The Dedicated Hybrid Engine (DHE) uses a clean-sheet approach to boost efficiency without abandoning the internal combustion engine entirely. The project aims to make hybrid vehicles more accessible by reducing the cost of the complex hardware that typically accompanies them.
The DHE configuration diverges from the power-split designs common in current hybrids. Instead of a single planetary gearset, the system uses a dual arrangement—one at each end of the crankshaft. This setup means there is no separate differential required, which simplifies the rear axle assembly. The engine itself is a radical departure from modern engineering standards, eschewing overhead cams for a pushrod design that operates a single cylinder head.
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Engineers built a proof-of-concept 1,599cc inline three-cylinder engine to test the principles. To keep costs down, the engine uses a monoblock casting with just two valves per cylinder and no variable valve timing. It lacks journal bearings, relying instead on roller bearings for the crankshaft, connecting rods, and camshaft to cut friction. The design is undersquare, meaning the stroke is longer than the bore, which improves thermal efficiency by reducing heat loss to the cylinder walls.
Comparing this to the GDCI program that Nayan Engineer previously led at Hyundai, the strategy here is notably different. That earlier initiative struggled to balance the conflicting demands of diesel efficiency and gas-engine cost. The DHE avoids those conflicts by sacrificing high-rpm power for extended periods of efficiency, accepting lower peak output in exchange for better economy. It is a more pragmatic approach to hybridization that prioritizes the total cost of ownership over maximum performance numbers.
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The Detroit Research Center in Michigan developed the concept. If his name rings a bell, he helmed a gasoline direct-injection compression-ignition (GDCI) program at Hyundai that we reported extensively on before that company—along with Mercedes-Benz (DiesOtto) and General Motors (HCCI)—all figured out you can’t have your diesel-engine fuel economy and eat gas-engine cost and emissions, and canceled those programs. His small team conceived of the