“What is the most common bank angle in degrees for a V8 engine?” — The most common V8 bank angle is 90 degrees.
The bank angle is the angle between the two cylinder banks. A 90-degree layout works especially well for a V8 because it supports good primary engine balance and relatively low vibration. It has therefore become the conventional arrangement for many V8 passenger-car, truck, and racing engines.
Ninety degrees is common, not universal. Some V8s use narrower angles to fit transverse front-wheel-drive engine bays. Ford and Volvo, for example, produced 60-degree V8 applications, while other specialized engines have used different angles for packaging or design reasons.
The crankshaft design also matters. A cross-plane crankshaft is common in road-going 90-degree V8s and helps achieve smooth operation, though it can produce uneven exhaust pulses without carefully designed exhaust systems. Flat-plane crankshafts can make a V8 rev more quickly and produce evenly spaced exhaust pulses, but often bring more vibration.