Allison-Engined P-51 MustangA definitive technical guide to the early Allison engined P 51 Mustang variants. While the introduction of the Merlin engine did improve the Mustangs performance and produce the bubble canopied fighters with which we associate the name, credit must be given to the Allison engined variants that preceded it. From its inception in early 1940, the Mustangs development was extraordinarily rapid such was the need for a fighter at the time, and the