German Engines.

Ive got a question about german engines.the king tiger was underpowerd because of a 700hp engine i think, why wouldnt germany stick in a Charomsky ACh-30B 1200hp or even more powerful airplane engines and just modify it for a normal manual transmission? it could be possible wouldnt it, most of the late german tanks were all underpowered and the tiger, kingtiger and jagdtiger all used the same engine.