A Question About Engine Noises

"Audi-os, Amigos!" (audi-os-amigos)
06/11/2014 at 15:00 • Filed to: V12, Engine Noise

In my own, flawed observation, I've noticed that V12 engines tend to have a fuzzy, buzzing sound to them. Like a swarm of Africanized killer bees.

I've also noticed that four cylinder engines have a lower, machine-gun kind of noise. Like dragging a cheese grater across cell bars in a big hollow trash can.

My question is this: does this "fuzzy" sound made by V12s (and conversely, the "banging" sound of four-bangers) come from the fact that there are more cylinders, and so combustion (or perhaps thrust) is more continuous, thus creating a fuzzy, harder-to-distinguish-where-one-ends-and-the-other-starts quality?

Thanks for your trouble in educating the unworthy. Here's my own little four-banger for your trouble.

DISCUSSION (31)

tromoly > Audi-os, Amigos!
06/11/2014 at 15:04

Yes. A 12-cylinder has three times as many explosions as a 4-cylinder in the same amount of time, as you said it'll make it harder to distinguish between them.

Demon-Xanth knows how to operate a street. > Audi-os, Amigos!
06/11/2014 at 15:05

Exhaust pulse timing and overlap. That's also why different V8s sound so vastly different. The patterns mix in differing ways.

feather-throttle-not-hair > Audi-os, Amigos!
06/11/2014 at 15:07

confession: I think straight sixes and rotaries sound awful and that v12s sound worse than v8s.

For the record I'd own cars with any of the engine types I just complained about.

Audi-os, Amigos! > Demon-Xanth knows how to operate a street.
06/11/2014 at 15:07

Can you explain? Because I have noticed that, for example, the V8 in the CTS-V sounds different from the V8 in the old RS4 which sounds different than the V8 in a '69 Charger.

crowmolly > Audi-os, Amigos!
06/11/2014 at 15:07

A few things involved IMO.

1.) Number of cylinders

2.) Firing order and cam timing

3.) Engine stroke allowing quicker rotating assembly acceleration

All are factors in the exhaust pulse frequency out the tubes. You can also throw in manifold/header design and thickness, exhaust design, crossover pipes, mufflers, and so forth.

505Turbeaux > Audi-os, Amigos!
06/11/2014 at 15:07

speak up, I cannot hear you V12

Kinja'd!!!

Manuél Ferrari > feather-throttle-not-hair
06/11/2014 at 15:09

Do not let YSI see this comment!

Audi-os, Amigos! > 505Turbeaux
06/11/2014 at 15:10

OI U AVIN A GIGGLE THERE M8??? WOT??

Kinja'd!!!

Jonathan Harper > tromoly
06/11/2014 at 15:11

Plus just generally more working parts to create a mechanical sort of buzzing sound.

505Turbeaux > Audi-os, Amigos!
06/11/2014 at 15:11

lol another over muffled 12 pot m8

feather-throttle-not-hair > Manuél Ferrari
06/11/2014 at 15:12

heh...well to be fair, I've bought a brand new sports car that I thought sounded shitty before, so it's not the most important thing on my shopping list.

Audi-os, Amigos! > 505Turbeaux
06/11/2014 at 15:13

The distributor looks like a Chestbuster from Alien.

Stupidru > Audi-os, Amigos!
06/11/2014 at 15:13

Just like everybody else said it's about the density of the explosions, but let's not forget the exhaust routing and overall geometry of the engine. A short stroke engine will often have a more buzzy sound (because more revs are required to make the same power) than something with a long stroke, ala Ford's PowerStroke V8s. There are valve overlaps and spark timings that also play a large part in the overall sound an engine makes.

Arch Duke Maxyenko, Shit Talk Extraordinaire > Audi-os, Amigos!
06/11/2014 at 15:14

Bore, stroke, firing order, shape of the combustion chamber, exhaust pipes, intakes, etc, etc.. there are so many variables to account for that your question has no answer.

RamblinRover Luxury-Yacht > Audi-os, Amigos!
06/11/2014 at 15:14

Timing order leads to different cylinders exhausting at different times, which then join one another in various ways. Depending on how far the puff of exhaust gas has to travel, it can be delayed compared to other cylinders enough so that it changes the sound of the cylinders *together*, i.e. after they've joined in x number of pipes. You might have "pop-pop, pop-pop, pop-pop" from one engine, and "poppoppop, pop, poppoppop, pop" from another.

Manuél Ferrari > feather-throttle-not-hair
06/11/2014 at 15:14

Haha the sound must be really low on your list then.

One thing I've noticed about I6s and V12s is that how they sound seems more impacted by the exhaust setup than other engines. A V8 with a freer flowing exhaust doesn't tend to sound different, just louder. But some straight sixes and V12s sound "wrong" until they get good exhaust.

505Turbeaux > Audi-os, Amigos!
06/11/2014 at 15:14

I dont know why I am dying laughing here, but you are so goddamn right

Audi-os, Amigos! > Stupidru
06/11/2014 at 15:14

A short stroke engine will often have a more buzzy sound (because more revs are required to make the same power) than something with a long stroke, ala Ford's PowerStroke V8s.

This is a great answer. Thank you.

Audi-os, Amigos! > Arch Duke Maxyenko, Shit Talk Extraordinaire
06/11/2014 at 15:15

Whoa, dude.

Audi-os, Amigos! > 505Turbeaux
06/11/2014 at 15:16

Now it's all I see and it's grossing me out. I regret posting this.

Audi-os, Amigos! > RamblinRover Luxury-Yacht
06/11/2014 at 15:17

Fantastic answer. Thanks.

Saracen > Audi-os, Amigos!
06/11/2014 at 15:18

The rumble you hear from cross-plane crank V8's is a result of exhaust pulses from multiple cylinders overlapping, basically amplifying the noise. This occurs in engines using a vee arrangement, as you always have a cylinder from either bank firing at the same time. Inline engines do not have any exhaust pulse overlap.

Those three V8's you mentioned all sound different because of differences in displacement, firing order, exhaust layout, valvetrain layout, etc...there are a lot of factors that do into engine sounds.

the exception is Flat-plane crank V8's (Ferrari, Maserati, Lotus Esprit V8) which do not have any exhaust overlap, and as such sound like two four bangers screaming away.

A V12 will sound like two straight sixes, with exhaust amplified by the exhaust overlap. You're also hearing a lot of valvetrain sounds.

feather-throttle-not-hair > Manuél Ferrari
06/11/2014 at 15:20

yeah, I'd agree with your exhaust theory, especially with the straight sixes.

One of the worst sounding cars I've ever heard was a super clean modded e46 m3. Holy shit, like bees and nickels in a coffee can.

As for my car, yeah, I like a good noise, but it isn't a deal breaker. Would totally have rocked the buzzy m3.

Demon-Xanth knows how to operate a street. > Audi-os, Amigos!
06/11/2014 at 15:22

Lets take the word "bang", and call that an exhaust pulse...

bang.....bang.....bang.....

Now take a two cylinder side by side:

bang..bang..bang..bang..

Now take a V twin:

bangbang...bangbang...

Now a 4 cylinder:

bang.bang.bang.bang.bang.bang.

Now a 6 cylinder:

banbanbanbanbanbanbanban

V12:

banbanbanbanbanbanbanban

anbanbanbanbanbanbanbanb

flat plane V8:

bang.bang.bang.bang.bang

ng.bang.bang.bang.bang.ba

cross plane V8:

bang..bangbang..bang.bang

ng.bang..bang..bangbang.ba

Manuél Ferrari > feather-throttle-not-hair
06/11/2014 at 15:23

It's crazy how different the E46 M3 can sound!

Stock it sounds ok-ish

With bad exhaust it sounds terrible

The factory-installed on the CSL makes it sound majestic

Yowen - not necessarily not spaghetti and meatballs > Audi-os, Amigos!
06/11/2014 at 15:25

Yes, more explosions in the same amount of time will generate a distinctly different sound. This will also make a car much smoother. Which is also why one, for example, Fords new 3 cylinder they had to add a balancer on the cam to smooth out the engine, since explosions are so much more infrequent, it would make the car a lot rougher if they didn't have an off-center weight carefully implemented to make it smoother.

Demon-Xanth knows how to operate a street. > 505Turbeaux
06/11/2014 at 15:36

I can't hear you over how V12 this is...

CobraJoe > Audi-os, Amigos!
06/11/2014 at 15:36

I can vouch that the engine sound is dependent on the air flow of the engine.

I just finished a head and cam swap on my '88 Thunderbird, so I should be going from roughly 155hp to 225hp (probably more, I have a better intake now too), and the engine sound went from a slightly noisy grumble to a full loud booming rasp without any change to the exhaust at all (It had an off-road H-pipe and glasspacks with no tailpipes when I bought it).

Before that swap, I was considering changing the exhaust to something that sounds better, now I absolutely love the sound but I'll probably have to change it to something quieter. All of that because of some extra air and fuel flow and two spark plugs changing order.

Audi-os, Amigos! > Demon-Xanth knows how to operate a street.
06/11/2014 at 15:43

WOULD THAT I HAD MORE THAN 1 RECOMMEND TO GIVE YOU FOR THIS POST

DipodomysDeserti > Audi-os, Amigos!
06/11/2014 at 20:32

Subaru 4 bangers sound like sewing machines.

blairl > Audi-os, Amigos!
06/12/2014 at 17:27

Kinja'd!!!

gross