Hemi 426 Engine - This intricately detailed replica is Hand Assembled. When the 426 Hemi was introduced in 1964 it was strictly a racing engine. The street version differed from its racing cousin by virtue of a lower compression ration (10.25:1), milder valve timing, and different intake and exhaust manifolds. For reliability, cast iron heads were used instead of aluminum. Very little changed inside the 426 Hemi throughout its eight year production life. Chrysler never changed the engine's advertised horsepower and torque ratings, which stood at 425 hp at 5,000 rpm and 490 foot-pounds of torque at 4,000 rpm.