Power Per Litre!

This is along the lines of the maximum power topic, but it is a bit different. The goal is to get the engine with the highest power per litre. The engine cannot fail. For example, an engine can have a 0 MTBF without failing, but this is only due to a bug that dramatically reduces the MTBF after 200hp per litre.
Here is my best: 446.9hp per litre.
Here is my best: 446.9hp per litre.