There is no free hydrogen inside the chamber of a gas powered vehicle.
(actually, a slightly technically incorrect statement because there is an incredibly small, almost immeasurable amount of free hydrogen it the air around us. Mostly resulting from the breakdown of water molecules by ultraviolet light. This happens in the far upper atmosphere far more than down here.)
Not anymore anyway. When compression ratios were up to 13:1, some plasma was created, but not at 8.5:1.