BMW Sets Speed Records with Hydrogen fuelled V12

This allowed the engineers to set up and tune the engine specifically for hydrogen requirements, for example by using special valve seat rings made of an appropriate material. The reason for this necessity is that hydrogen does not have the lubricating effect of a conventional gasoline/air mixture.

And it is worth noting in this context that this need to cope with a lower level of lubrication already arose in the past when introducing unleaded gasoline, production engines since then being built with even stronger and more resistant materials.

A fundamental consideration is that the combustion properties of hydrogen are quite different from those of gasoline or diesel: While hydrogen burns faster than conventional fuels under normal air pressure, the combustion temperature is slightly lower than in the case of gasoline.

Inside the engine the high combustion speed of the hydrogen/air mixture generates a higher temperature than in an engine running on gasoline. Engine management of the BMW H2R Record Car has been modified accordingly, the hydrogen/air mixture not being ignited until the piston reaches top dead centre, thus ensuring maximum output. With a gasoline/air mixture burning relatively slowly, by comparison, the mixture must be ignited at an increasingly early point as a function of engine speed, the pressure peak thus being reached just as the piston starts to move down.

A significant advantage of the higher combustion pressure of the hydrogen/air mixture is that the generation of more power from the same amount of energy means a higher degree of efficiency.

As desirable as the high standard of ignitability of hydrogen within the engine may be, it naturally requires a great deal of attention outside of the combustion chamber.

To avoid misfiring, for example, BMW's engineers have developed a specific gas cycle and injection strategy, with BMW's VANOS infinite camshaft adjustment masterminding the share of residual gas according to specific, on-demand requirements.

Before the hydrogen/air mixture is able to flow into the cylinders, the combustion chambers are cooled by air to ensure that the fuel/air mixture is not able to ignite in an undesired, uncontrolled process.

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