On my flight sim I have the Realair Griffon powered Spitfire MKXIV and does she ever go. Keep thinking when flying it why didn't North American put a Griffon in the P-51. I think there are some race type Mustangs with it but don't know about military ones.
Bob
Probably becaused there was little need. The P51 performed well enough during the war and for some years after as a frontline aircraft with the Merlin. It would also have involved a fair bit of re-engineering, due to the increase in power and torque (large vertical surfaces at least - which they then did with the H anyway!), and possibly a bit of weight distribution - the Griffon 65 as used in the Mk XIV Spitfire weighed in at about 900kg whereas a mid-late war Merlin 61 (Mk VII, VII, IX and XI, roughly equivalent to P-51) around 750kg, with the Griffon being longer (larger moment) too.
Couple this with the fact that a Griffon Mustang would take time to develop, set up a factory in the states to produce the engines under licence, then convert pilots used to a Merlin engined fighter to a heavier Griffon one, with a prop that rotates in the other direction, and it probably wasn't worth it. Packard's Merlin was a damn good engine and well up to the task.
