Initially, the P-51B and C had the Packard V-1560-3 engine rated at 1400 hp for takeoff and 1450 hp at 19,800 feet. There were 400 P-51B-1-NAs and 250 P-51C-1-NTs built.
total of 1990 P-51Bs
total of 1750 P-51Cs
V1650-3 production was ~17% of all P-51B/C production.
At 61" of Hg
V-1650-3
critical altitude, low blower - 13,750'
critical altitude, high blower - 25,800'
V-1650-7
critical altitude, low blower - 8,500''
critical altitude, high blower - 21,400'