Engine's roar

ford
bronco

#1

We all know a four does not sound like an eight, but why doesn’t a four cylinder engine at 4000 rpm sound like a V8 at 2000 rpm. (Both engines should be firing the same number of detonations per minute)


#2

I doubt detonations per minute is the main factor in how an engine sounds. Displacement is probably bigger factor.


#3

Most Harleys have what, 2 cylinders? My Goldwing has 6 cylinders. Sound doesn’t appear to be related to number of cylinders.


#4

Lots of variables affect engine sound – number of cylinders, exhaust system, firing order, cylinder angle, displacement, turbo/super chargers, etc.

Twotone


#5

Displacement, piston travel, valves, and intake/exhaust sound modifiers.

Want your 4-banger to sound more powerful for free? Remove the intake resonator.

Want it to sound like a race car? Remove everything on the exhaust behind the catalytic converter. The V8 guy will be amazed. And then he’ll go deaf.

:wink:


#6

Blip The Throttle On My Old (Former) 4 Cylinder VW Dune Buggy With A Holley Bug-Spray Carb, 1700 CC Jugs, And Tee-Pee Exhaust (With No Muffler) And The Sound Said, " Get Your Kids Off The Street ! "

Maybe horizontally opposed was part of the fomula. Headers, exhaust pipe length or exhaust arrangement could be another.

CSA


#7

Why Did The Old 650 Triumph Bonnevilles (360 ?) Sound Like Music To My Ears (Even Without Muffler) ? Could It Be That Some 2 Cylinder Motorcycles Have 360 Degree Cranks And Some 180 Degree ? I Think So.

When I was a kid my 64 Honda 305 Super-Hawk (180 ?) sounded like all Hell was breaking loose (not very melodic) when I’d remove the mufflers and cruise the neighborhood. A cold day was like adding a super-charger to it.

CSA


#8

#9

American V-8s usually 90 degree crank throws which allows a smoother firing order, but results in the exhaust exiting the manifolds in uneven intervals. Listen to a Ferrari V-8 with a “flat plane” crank shaft. They have a very distinctive howl that is nothing like the rumble that american V-8s produce.


#10

I doubt detonations per minute is the main factor in how an engine sounds

In the 4 banger, it’s the difference between sounding like the PH in “my PHat ride” and an angry insect… :wink:


#11

This is a very good explanation for the syncopated sound of a 90 degree crankshaft V8 that otherwise has an even firing order. When Cadillac released their first V8 in 1915, it had a flat plane crank similar to many WW1 airplane engines. Manufacturing techniques advanced to where Cadillac could release a 90 degree V8 crank in 1923 which then made the rumble sound but reduced vibration. A flat plane crank such as what Ferrari and some other racing cars use does not require counterweights which makes it lighter to enhance acceleration.