hey dogdays; my dad bought a late 40s early 50s wooden speed boat that had a 4cyc (cast in block Chrysler gray marine) motor with a 2 spd fwd and rev. it looked like a continental. Chrysler built marine engines for the navy, pt boats. these engines could run on low octane gas, rather than av gas that the Allison and rolls Royce aircraft engines needed. never thought about hopping one up. mikeh