how does the cylinder architecture of an engine affect its sound?

Question

I find the technical aspects of engines, especially car engines, fascinating, but don’t know much about them. I know the basic principles of an internal combustion engine and that’s about it.

But when I listen to different cars, there seem to be typical sounds for different engines: V8 cars, like the Boss 429 Mustang or Alfa Romeo Montreal, tend to have this deep thundering sound with the cool “stutter” while idling. Cars with V6 engines, like the AMG C43 or Audi S4 (to me) have a more aggressive humming sound, while cars with V10 (e.g. the Huracan) seem to have a more high-pitched screeching sound. Is the cylinder architecture the reason for that or is it something else that affects the sound? Or is my perception just off and the engine type has no correlation to sound?

In: 14

Answer 1

This is a complicated subject but I’ll ELI5 it to keep it short. There’s two main things that affect a car’s sound. The first is the engine arrangement and firing order, that is how many cylinders it has, what arrangement they’re in, and the order in which they fire, and the second is the exhaust system, and to a lesser extent the intake. As far as the engine arrangement and firing order goes there’s a myriad of practical reasons to choose one over the other before you get to sound but that’s not to say it’s not important. A great example is parallel twin engines in motorcycles. Long considered to be dull and boring, they’re experiencing a resurgence in popularity, thanks to no small part to the 270degree firing order, which in layman’s terms means that those parallel twins sound like V-Twins, which are considered characterful and torquy. As far as the exhausts go of course there’s a ton of considerations there too since no production vehicle can have a free flowing straight pipe exhaust but even so they have engineers working specifically on the acoustics of the engine so that they get a specific desirable sound profile as much as they can, considering of course there’s legal limitations to noise and also catalytic converters drown out a lot of the sound.