Why was the Chrysler Hemi used in Nitro racing? I have a couple of "Experts" at work claining it was the superior hemi design. Of course explaining to them there was several version of the Hemi doesn't change their minds. The 331/392 and 426 Hemi are completely different engines. I think it was based on the fact that 392 in the early sixties that could be bored and stroked to easily was a big a factor as any other. BBC, Cleavland Fords, Boss 429 are all Semi-Hemi engines from what I understand.