Toyota has been competing in the Japanese Super Taikyu series since 2021 with a hydrogen-fuelled Corolla. This Corolla H2 Concept is powered by a 1.6 litre I3 turbo out of the GR Yaris modified to run on hydrogen. Last year and the year before it was fuelled by gaseous hydrogen compressed to 700 bar. Now it is fuelled by cryogenic liquid hydrogen, which greatly increases the range of the car and allows for better packaging.
However, the deployment of hydrogen as a cryogenic liquid brings a new set of challenges. The required temperature is -253 C and having taken hydrogen down to this it has to be stored in an insulated tank to maintain that temperature and minimise evaporation. A setback earlier this year was a fire during testing prior to the first round of the 2023 Super Taikyu series. This was due to a leak from a hydrogen supply pipe within the engine compartment.
Following the fire Toyota has modified the Corolla’s hydrogen liquid supply system and has put the car into competition. The greatest challenge is the liquid hydrogen pump, which cannot use lubricating oil since that contaminates the hydrogen supply. This prompted the team to plan two pump changes during the Fiji 24 Hour race in May. Toyota admits that the first such change took four hours; the second three hours…
Since then the pump has been revised with what Toyota describes as a buffer system reducing demand on its gear drive. It has also been possible to reduce the hydrogen supply pressure allowing use of a smaller pump drive battery. The upshot is a pump that can safely run 30% longer. At the same time the hydrogen piping in the vicinity of the engine has been moved further away from the hottest (exhaust) area and also heat shielded.
Other improvements have reduced car weight from 1950 kg to 1910 kg. Additionally the refuelling equipment has been lightened and put under electronic rather than manual control with the refuelling time reduced from about 100 seconds to about 60 seconds. These improvements were in place for the Autopolis five hour Super Taikyu series race on July 30. Unfortunately the pioneering car retired from that event after completing 91 laps.