Head design- adding cylinders

[OdinYggd]

A lot of engines right around WWI and WWII were indeed built in a modular fashion. Each head and cylinder was one assembly, and attached to a bottom end that was similarly modular.

Engines were then built up by assembling banks of modules in this way until the required size was reached, and plumbed together using simple manifolds.

It wasn't until monobloc engines became the normal expectation that you had to redesign the engine to change how many cylinders it had. Fairly sure it was around mid-late WWII when aircraft engines started being manufactured with all of the cylinders in a single casting, doing away with the discrete cylinder constructions used up to that point in all except radial type engines.

I have seen a few engines on youtube that were built by joining single cylinder small engines together to create larger engines, but these would offer rather poor performance and be prone to engineering problems not encountered in a mass produced engine design.

[Punch]

Adding more cylinders and a longer crank would lower the critical torsional oscillation frequency of the crankshaft. Thus longer engines need stiffer crankshafts. But the increase is not that big from V8 to V10.