Honda has confirmed that on July 25 at Japan’s Okayama circuit it gave its 2024 Super GT challenger its first shakedown run. Honda is one of three manufacturers supporting the GT500 class of this Japanese series and for 2024 it has a brand new car with an evolution of its existing engine.
Currently Honda campaigns a mid-engined rear wheel drive car fashioned after the NSX road car. That GT500 contender was restyled for 2022 along the lines of the NSX Type-S, the final iteration of the road car, which is now out of production. As such Honda is for 2024 switching to the Civic Type-R, which follows Nissan and Toyota’s rival machines in having a front engine location albeit rear wheel drive.
All of these GT500 contenders have an engine to regulations that impose a 2.0 litre I4 turbo with direct injection. Maximum rpm is 9500, maximum plenum pressure is 3.5 bar and maximum fuel pressure is 350 bar. On top of that there is a maximum fuel flow of 95 kg/h imposed by a mechanical restrictor. The engine has to weigh at least 85 kg and to run for over 5000 km between rebuilds.
The Honda engine designed and developed by HRC for GT500 is the HR-420E, blown by a single Garrett turbo. Run by a Bosch Motronic engine management system it is an all-alloy dry sump unit with double overhead camshafts operating four valves per cylinder. It is also employed in Super Formula, which is the top single seater series in Japan.
The HR-420E has a 15:1 compression ratio and was developed using Honda’s knowledge of lean burn engines for Formula One. Honda claimed that it was hardest hit by the introduction of a ‘carbon neutral’ control fuel for 2022 but one can expect the 2024 derivative to be fully competitive in Super GT.