09/04/2026
Southwest Research Institute (SwRI) is pushing hydrogen internal-combustion engine technology toward real-world applications with a 5.0-liter medium-duty engine designed to deliver diesel-like performance — without fuel-derived CO₂ at the tailpipe.
But converting an engine to hydrogen isn't as simple as swapping the fuel.
SwRI redesigned the cylinder head, piston, and combustion chamber, developed hydrogen-specific fuel injection strategies, added a variable-geometry turbocharger, and engineered the engine to move enormous amounts of air. The experimental engine can run at more than 2.5 times stoichiometric airflow and has seen boost levels as high as 3.5 bar.
And hydrogen brings some unique challenges, including pre-ignition, NOx formation, the lack of charge cooling, and even an unusual ignition-system issue known as “ghost spark.”
The result? A hydrogen-fueled ICE that matched the project’s target of approximately 215 horsepower and 450 lb-ft of torque, while producing dramatically lower engine-out NOx than the diesel baseline.
Hydrogen may not be the one-size-fits-all answer to decarbonization, but SwRI's work demonstrates something important: the internal-combustion engine still has plenty of potential.
