Now, as far as the Japanese are concerned, they also used many types of radial engines.
First among the list is the Nakajima Sakae radial engines which powered the legendary A6M 'Zero' fighter, the J1N1 'Gecko,' and the Nakajima B5N 'Kate.'
12 series:
http://www.sim-outhouse.com/downloads/download.php?lloc=downloads&FileID=4373
21 series:
http://www.sim-outhouse.com/downloads/download.php?lloc=downloads&FileID=7303
Solobo's version:
http://www.sim-outhouse.com/downloads/download.php?lloc=downloads&FileID=7336
The Nakajima Ha 45 Homare was a powerful radial engine used by the Japanese for two of their very good fighter designs, the Kawaniski N1K 'George' and the Nakajima Ki-84 'Hayate,' along with certain versions of the Yokosuka P1Y1 'Frances.'
http://www.sim-outhouse.com/downloads/download.php?lloc=downloads&FileID=5083 (single)
Solobo's version:
http://www.sim-outhouse.com/downloads/download.php?lloc=downloads&FileID=5223
Update:
http://www.sim-outhouse.com/downloads/download.php?lloc=downloads&FileID=5232
Solobo's version III:
http://www.sim-outhouse.com/downloads/download.php?lloc=downloads&FileID=7444
The Mitsubishi Kensai was another radial design, used to great effect in the Aichi D3A 'Val,' the Aichi E13 'Jake,' and the Mitsubishi G3M 'Nell' level bomber.
http://www.sim-outhouse.com/downloads/download.php?lloc=downloads&FileID=5130 (Single).
There is no twin sound pack for this version.
A four-engined is available for the Kawanishi H6K 'Mavis':
http://www.sim-outhouse.com/downloads/download.php?lloc=downloads&FileID=12004
Adopted by Kawasaki, their Ha-series were essentially licensed-built versions of the Nakajima Sakae radial engine. These engines were used in the Kawasaki Ki-100, the Mitsubishi Ki-21 'Sally,' the Nakajima Ki-44, the Kawasaki Ki-45 'Toryu,' the Kawasaki Ki-46 'Dinah,' the Ki-102 'Randy,' the Ki-67 'Peggy,' the Ki-48 'Lilly,' and the Nakajima Ki-43 'Oscar.'
You can find the sound pack here:
http://www.sim-outhouse.com/downloads/download.php?lloc=downloads&FileID=7240
Ki-100 version (Ha-112):
http://www.sim-outhouse.com/downloads/download.php?lloc=downloads&FileID=7179
Ha-115 version for the Ki-44 'Tojo':
http://www.sim-outhouse.com/downloads/download.php?lloc=downloads&FileID=13780 (inside is a single and a twin version for the Ki-49 'Helen').
The Mitsubishi Kasei was an engine used in the G4M 'Betty' long-range bomber, as well as the J2M 'Raiden' the Nakajima B6N2 'Tenzan,' certain versions of the Yokosuka P1Y1 'Frances,' and the H8K 'Emily' flying boat.
There is a soundpack for multiple engines, found here:
http://www.sim-outhouse.com/downloads/download.php?lloc=downloads&FileID=13438
However, there is not a single-engined version.
There is also no sound pack for the small Mitsubishi 'Zuisei' engine which powered early versions of the A6M Zero, as well as the Ki-30 'Ann.'