I got my 206 endorsement on an "A". According to my ground school manual, the C18A produced a maximum of 317 hp with a 5 minute limit. Maximum continuous power was 270 hp. According to Bell, the transmission ratings for the B3 are identical, which means it has the same transmission although the
C20B gives it a lot more headroom in the temperature department:
http://www.bellhelicopter.com/en/air...06_jan_web.pdf