GM has developed many powerful engines over the years, with classics like the supercharged 600-plus-hp LS9 and the 400-odd-hp LS3 among the best-known. But the automaker's record is far from perfect, ...

Direct-injection engines were introduced with a promise that sounded ideal: more power, better fuel efficiency, and cleaner emissions, all from a more precise way of delivering fuel. On paper, the ...