Some V-12 and V-16 engines were historically considered and in some cases even produced by American car companies. Cadillac tested an 8.2 liter
V-12 engine in the mid-1960s for the
Eldorado, but canceled it because the company was still deciding between a longitudinal and transverse layout for the vehicle, and the V-12 would not have fit in longitudinally. In the end the car came equipped with a
500 cubic inch (8.2 liter) V-8 engine, so massive that a single piston had almost as much displacement as all four cylinders of a
Fiat 128. A
V-16 engine built from two V-8 engines was also considered by Cadillac one point during the mid-1960s, but was also canceled. However, a
702 cubic inch (11.5 liter) "Twin Six" V-12 was produced for GMC trucks in the 1960s, being cast as a single unit but featuring significant commonality with GMC V-6 engines.
While perhaps not to the extent of Cadillac, the V-8 engines on some muscle cars had massive displacements, with 427 cubic inches being close to 7.0 liters, still giving a massive piston size. Although the mentioned engines were considered or produced for luxury cars and trucks, I'm wondering how a V-12 or V-16 engine might have fared in a muscle car. To simplify logistics and reduce costs, the V-12 engines could have been based on V-6 or even straight six engines. A flat six engine such as the one used on the
Chevrolet Corvair could have been an option too. A V-16 could only use V-8 engine blocks for commonality (inline eight engines having fallen out of favor), and would likely be unwieldy for many roles, but it could be used by a company wanting to make a luxury vehicle.
How feasible would this have been? How would a V-12 or V-16 compare to a similar large displacement V-8 engine?