This was one of the most unusual performance Mustangs ever made. Ford was in fierce competition with Chrysler in NASCAR racing. The Hemi-powered Mopars had a slight advantage on the speedways due to the better flow of the hemi-heads on the 426 engines. So Ford decided to build their own hemi engine and came out with the Boss 429 engine in ‘69.

It was hard to tell how much the new engine helped because at the same time, Dodge racers were running the Charger Daytona that used a huge rear wing and big shovel nose clip. Meanwhile, back in Product Development, planners decided to make the new 429 engine part of the Boss Mustang option even though the Mustang didn’t race in NASCAR.

Like the Chrysler Hemi, the Boss 429 was HUGE! It was amazing that Ford was able to stuff the engine in the Mustang engine compartment. The car was actually somewhat of an odd-ball combination. Because the engine made the car very front-heavy, it didn’t handle as well as the Boss 302 and it wasn’t as quick as the Mach 1 or Cobra Jet Mustang. Dollar-for-dollar, the Boss 429 wasn’t the best performance Mustang to buy.

Back at the race track, NASCAR felt that things were getting out of hand with the Dodge and Plymouth winged cars and the slant-nose Torino Fords, so restrictions were placed on the big Hemi-powered cars, thus ending the monster powered NASCAR racers. Ford’s Boss 429 hemi effort was about 3 years too late.