Inside the JCB Hydromax

The JCB Hydromax will use two revolutionary production-based hydrogen internal combustion engines, each tuned to an astonishing 800hp. The crankshaft is the same one JCB uses in its 448 hydrogen and diesel engines – highlighting how the land speed car is built on production hardware.

One engine is mounted behind the driver and the other is mounted in front. These engines are based on JCB’s existing 4.8L inline four-cylinder spark ignition with port injection hydrogen engine. The JCB Hydromax also has a sophisticated induction system, with a single-stage motorsport turbocharger to help deal with the high altitude of the Bonneville Salt Flats.

During the development of the production engine, JCB turned to the motorsport industry for inspiration. The initial 448 prototype hydrogen engine was fitted with spark plugs designed for a Le Mans 24 hour engine. Even though the engine is built on production hardware, the JCB Hydromax engines were extensively rebuilt to suit the demands of breaking the speed record. The figures at the exhaust are striking. On the full record run, JCB Hydromax will consume just over 2kg of hydrogen – and produce 18L of water.

The foundational load bearing frame of the JCB Hydromax has a 350mm extension of the rear bodywork compared to the JCB Dieselmax, which will increase the aerodynamics and reduce drag. Under the main tail fin, there is also a subtle ventral strake offering a notable aerodynamic gain. Overall, the aerodynamic drag is about 10% lower than it was for the Dieselmax.

The car features a slightly raised nose tip that is sharp and square. Under the nose tip, the sculpted channels are designed to extract salt from underneath the bodywork of the car. This is because the salt from Bonneville Flats creates substantial aerodynamic drag underneath the bodywork. The salt spray extractors, which fire salt out along the sides of the car, are a major advantage to the JCB Hydromax design.

Underneath the bodywork, there is a steel frame chassis. The heavy-duty steel lattice is 10% lighter than the Dieselmax and is similar to that of a conventional racing car with minimal use of strong tubing. The driver, Andy Green, will sit in a composite monocoque sub chassis with a drag-racing style steel roll cage over his head. The cockpit itself sits 450mm further forward than the Dieselmax, in a more central location. The windscreen is sculpted to minimise drag and the hydrogen tank sits just behind the carbon fibre sub chassis.

Keeping the hardware alive is the key engineering challenge. The pistons alone require one litre of cooling oil every second – as much oil flow as the rest of the engine combined – to stop them overheating.

Instead of cooling inlets on the car, the JCB Hydromax uses tanks full of ice to cool the engine and other underbody components. One tank is located inside the nose structure, while the other is located in the hump of the bodywork behind the driver. 250kg of ice is needed for each run – with the tanks being drained and refilled each time.

A specially developed exhaust valve technology handles the temperatures generated by the 800hp/engine of hydrogen combustion. Each titanium turbo compressor spins at more than 150,000 rpm at close to 300°C, pumping the equivalent of a standard bathtub of air every half-second.