5. Hemi 426
From 1966 to 1971, the Chrysler Corporation produced the infamous Hemi 426 engine, the definitive muscle car engine of all time. It was the top-of-the-line engine option for select Dodge and Plymouth muscle cars. It was the most expensive and also the most powerful. The name, “Hemi,” comes from hemispherical combustion chambers inside the heads of the engine and “426” is its displacement measured in cubic inches. This engine was officially rated at 425 hp throughout its lifespan, but everybody knew this number was a joke. The Hemi technology allowed this engine to achieve a much higher rpm range than the standard big-block V8 engine of the day, and that meant more horsepower and torque.
Big valves allowed much better airflow, which also helped the power. Straight from the box, the Hemi 426 could produce around 500 hp without any problem. Most owners decided to do some modifications like new carburetor jets to easily get 550 hp without much work. That’s more than 100 hp above the factory specifications. Horsepower has always been a way to distinguish fast cars from slow ones, but the statistics have not always been real. Although the car makers have their reasons, it’s easy to test them to find out the actual horsepower. Thankfully, today’s carmakers are more truthful about horsepower.