Why were V engines 12 cylinders?

Shortround6 said:

The car engines could also afford to be heavy and low stress. From Wiki so usual disclaimer.

"The original Cadillac V16 could be said to be two straight-8 engines on a common crankshaft and crankcase, because each bank operated entirely independently of the other with no other shared components. It sported a narrow 45° bank angle for use in the new Cadillac chassis (which became the Fleetwood).[4] The engine was well engineered, with a counterweighted crankshaft (quite a mathematical challenge at the time), overhead valves,[5] and hydraulic tappets.[5] It also had only two single barrel carburetors,[1][5] one for each bank "
"The 452 V16 had a 3 in (76 mm) bore and a 4 in (100 mm) stroke, giving an engine displacement of 452 cubic inches (7.4 L). It was therefore known as the Series 452. Cadillac initially rated the engine at 165 bhp (123 kW).[1] It was capable of powering the heavier models to speeds in excess of 80 mph (130 km/h), and 100 mph (160 km/h) for some of the lighter examples. "

another article says the engine, with accessories weighed around 1300lbs or about as much as as an aircraft engine of much greater size and power ( even a Kestrel is much more powerful and lighter .
This a problem trying to compare automobile and aircraft engines. Different goals meant different choices were made.

Click to expand...