The Frog 80 Mk1 came out in 1957-nominal capacity 0.8cc. It replaced the none too successful 0.5cc Frog 50 which was dropped from the Frog engine line. The 80 had an o-ring sealed contra-a la McCoy and OK Cub diesels, making the feel a bit odd to Brit and downunder modellers, and it was replaced by a conventional lapped contrapiston in the mk2 version which appeared a few years later (1961?)-the latter version remaining in production into the 1970's (made by DC not IMA by then!) until the Frog range faded away ca 1974 or 75. No significant difference in performance between the two Mks of Frog 80.

ChrisM
'ffkiwi'