Why doesn't India build large marine diesel engines?

As recently as 2024, the Indian Navy upgraded the Brahmaputra-class frigate INS Beas with imported 6 MW Caterpillar engines. That single detail captures the gap: over 90% of engines above 6 MW on Indian vessels are sourced from just five foreign manufacturers — MAN Energy Solutions of Germany, Wärtsilä of Finland, Mitsubishi Heavy Industries of Japan, Volvo Penta of Sweden, and Caterpillar of the United States.

A large marine diesel engine is not a scaled-up truck engine. It demands high-temperature, high-stress alloys for cylinders and crankshafts, precision casting and machining of very large components, tribology fine enough to control wear across a ship's decades-long life, and — increasingly — proprietary electronic control units running closed-source firmware. That last point matters: dependence does not end at purchase. It extends to diagnostics, software updates, and maintenance, all held by the original maker. Marine engines account for 15–20% of a ship's total cost.

India's position is honest to state: emerging, not established. On 2 April 2025, Kirloskar Oil Engines Ltd signed a Project Sanction Order with the Indian Navy under the Make-I initiative — a ₹270 crore programme with 70% government funding — to design and develop a 6 MW medium-speed marine diesel engine. CEO Rahul Sahai has confirmed an April 2028 delivery deadline for the V12 engine, with a dedicated manufacturing facility in Nashik nearly operational. The core design is KOEL's own, with vendor support from Europe's Ricardo plc for simulations, pistons, and fuel injection. The contract also covers scalable designs from 3 to 10 MW, with a 20-cylinder, 10 MW variant targeted for larger vessels. Separately, DRDO is seeking collaborations to develop indigenous diesel engines for Project-76 submarines.

The gap persists because the foundations beneath the engine are themselves still forming. India lacks prior expertise in high-performance marine diesel design — DRDO's submarine work relied on nuclear propulsion, leaving a hole in conventional diesel technology. Limited domestic capacity in high-chromium steels and nickel-based superalloys has already constrained aerospace engine programmes. Combustion simulation software, ECU systems, and the manufacturing process capability for very large components all sit at the emerging stage. The strategic stakes are real: export control regimes in the EU, US, and Japan can impose embargoes under national security pretexts.

What it would take is patient assembly of these layers alongside the prototype. India's shipbuilding industry grew from $90 million in 2022 to $1.12 billion in 2024, yet holds only 0.06% of the global market. The Navy's roadmap targets engine trials by 2028–29 and full propulsion self-reliance by 2040 — a long climb, now begun.