P-51B MustangP 51B Mustang airplane model. In September 1940, the Packard Motor Company of the U. S. began license production of the Merlin V 1650 1 engine in Detroit, Michigan. With a new supercharger drive, a new V 1650 3 was mated to the first P 51B. Both the U. S. and England started the Merlin engine modification idea almost simultaneously. 10 airframes were modified in the U. S. with the Merlin and these became the basis for the most successful fighter