3. Pontiac 400 Ram Air IV
Back in the late ’60s, Pontiac’s Ram Air engines were one of the hottest mills in the muscle car class. This engine featured a four-barrel carburetor with the famous Ram Air induction system. The ratings were 360 HP in its RA III form. They installed those engines in GTOs, making them the perfect street racers of the era. However, in 1969, Pontiac presented the Ram Air IV version of the same engine with the same advertised horsepower rating of 360 HP. The two engines looked the same, but the RA IV had much different internals underneath.
It had different engine heads, camshafts, and valves. It also had more compression and a higher rev limit. The Ram Air IV was capable of much more than 400 HP. However, the factory decided to rate it at 360 HP for insurance reasons. Unfortunately, the Ram Air IV was an expensive option so Pontiac didn’t make many of them.