Like the J-5, the J-6 Whirlwind was based on the J-4 of 1924, this time with cylinders of increased bore (from 4.5 to 5 inches).
The first J-6 (the Whirlwind 7) flew in 1925. In 1929, the Whirlwind 9 was introduced and in 1930, the Whirlwind 5. All three shared the same cylinder design (5 x 5.5 in); they differed in the number of cylinders.

The Whirlwind 9 (R-975) was also produced by Continental during World War II.

models

• J-6 Whirlwind (R-540): 165-175 hp (123-131 kW)
• J-6 Whirlwind 7 (R-760): 225-320 hp (168-238 kW)
• J-6 Whirlwind 9 (R-975): 300-420 hp (223-313 kW)

specifications

• 9 cylinder, air-cooled, radial
• displacement: 973 cubic inches (15.9 litres)

used by

• Bellanca CH-300 Pacemaker
• Curtiss Robin
• Curtiss-Wright CW-22 Falcon
• Ford C-9 Trimotor
• Lockheed R3O
• Vultee BT-15 Valiant