Why do Italian & American V8s sound different?

Flat crank!

 

More info for those of us not as technically knowledgable as you?

 

There has to be more to it than that, or a Maserati would sound like a Chevy

 

Think of a V8 crankshaft as four bicycle cranksets together on one axis, like eight pedals side by side.

American V8s have a pedal every 90 degrees; Ferrari V8s have pedals every 180 degrees; hence the term "flat". The result is a different rhythm of the firing of the cylinders, and a different rhythm to the exhaust.

Also, the noise from the four overhead cams and two timing belts driving four sprockets vs. single chain driven cam operating pushrods adds to the distinct sound.

 

Plus the exotic car makers are willing to spend more money on the exhaust system; in addition to tuning the sound (as well as the resonances), things like resonator tips at the end -- which cost money that companies like GM don't want to spend -- affect the sound, too.

 

Not just the 180 degree crank ---

It's a combination of the flat crank, pairing of the pistons on the crank, and the firing order. This combined arrangement also allows for exhaust timing which accentuates (allows them into the exhaust manifold) the higher-pitched notes of the combustion event.

Check out the firing order for a Ford or Chevy V-8 --- it's very different from that of a Ferrari V-8...

 

Simple answer: flat crank v8: exhaust alternates between banks.
Yank (cross-crank) v8: you sometimes get two "puffs" in a row into the same exhaust (presuming a dual exhaust on a "muscle car".)

Long answer: Use "search" for "flat crank". This has been covered in excruciating detail in older threads.

 

And the carb cars have that lovely intake sound.
Cheers,
Tom

 

It's all about the mufflers and tailpipes.

 

flat plane crank

 

I don't know if this has much to do with it but in general the American V8s (especially older V8s) are larger displacement and lower rpm engines while European V8s tend to be smaller displacements and higher rpm engines, thus they will sound different.

 

I think exhaust tuning has more to do with it.

This Maserati with a 90 degree crank sounds more like a Ferrari than an American v8

http://www.larinisystems.com/mediaFiles/qp%20take%20off%204%20joined%20the%20one.wmv

 

I say its firing order with exhaust tuning. Flat crank helps.

 

The classic Ferrari 'sound' comes from a number of interacting elements that line up n a synchronized chorous.

First comes the flat plane crankshaft. This gives each cylinder bank an even firing order LRLRLRLR whereas the typical american V8 has an off kilter firing order LRLLRLRR. The even firing order means that the intake and exhaust pulses are also synchronized and evenly spaced.

Next comes the headers. These headers are tuned for the power band of the engine, not too big, not too small, not too long not too short. The headers cause much of the low frequency rumble from these engines by setting up a standing wave pattern of pressure pulses.

Next come the intake system. Here the air path is essentialy straight (e.g. no turns) that enables the air to flow into the cylinders with minimal resistance. The straignt air flow and low resistance enables the velocity stacks to be tuned with the header to broaden the power band.

As the intake valve opens (with the still open exhaust valve) air begine to travel into the cylinder even before the piston starts dwonward from the negative pressure wave from the header. As the intake valve closes, there is considerable momentum in the air flow. When this reaches the closed intake valve, pressure builds until a positive pressure pulse runs up the intake and velocity stack finds air at atmosphereic pressure and sends a negative pressure wave back down. This negative pressure wave runs into the intake valve and sends a negative pressure wave back up the intake and VS, causing a subsequent positive pressure wave. much of the high frequency music of these engines comes directly from this process.

Just under the resonance point of the header there are an even number of intake cycles so that when the intake valve opens there is already positive pressure and momentum to take the fresh charge into the cylinder (also) even before the piston starts downward. Just above the resonance point of the header there is another even cycle count in the intake puls train. There are generally 8 or 10 cycles on the low intake resonance and 8 or 6 on the high RPM intake resonance. These broaden the powerband of the motor.

Finally, the throttle plates are positioined at the center of the intake path and at anything less than WOT damp out even order harmonics in the intake resonance so one hears the primary, 3rd order, 5th order,... of the air movements turned into that sonorous chorous. Even order harmonics end up sounding like an amplifier with cross over distortion, while odd order harmonics sound like an amplifier cliping the peak. Any music buff will tell you that odd is much better than even in sound quality.

The modern V8 engines also employ a 2 stage set of resonators. The air box covering the intake tracks is tuned such that at header resonance a positive pressure wave is above each intake velocity stack just before the intake valve opens. The great rush of air into the cyclinder reinforces this 'standing' wave resonance. These are known as helmholtz resonators.

At the end of this resonator is a smallish tube leading to the largish air filter box. The size and length of this tube damp out the resonator standing wave such that the mass air flow sensor gets a nice smooth flow of air and can thereby be used to give precise control to the FI system.

The difference betewwen Ferrari systems and other manufactures, is that Ferrari works to get the sizes, volumes, and resonance points to actually line up and sing. Whereas others just get them close enough to deliver the power.

 

I found that artice here on Ferrari Chat. I don't know who posted it originally.

 

That's what I've always been told.

Steve

 

If that were the case then you could make almost any car sound like a Ferrari and somebody would be doing it and that somebody would be making real good money.

 

The Maserati is flat plane also.

It is not all about rpms. My RS4 turns to 8000+, and it sounds like a NASCAR motor. Because in exhaust terms it has a lot in common with a NASCAR motor than a Ferrari V8.

V12's have a harmonic that makes them sound more like a chord than a single tone. My 512 sounded like a pipe organ! (so driving it was just like going to church )

I have not yet heard one in person, but a GT40 has a cross-over exhaust where the uneven power pulses are balanced from one side of the 90 degree crank V8 to the other. It is supposed to have it's own unique sound.
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The maserati looks like a 90 degree one to me.

http://eurospares.co.uk/partTable.asp?M=3&Mo=494&A=1&B=28000&S=

I think it is going to be real interesting to see which crank in in the new F149.
Will it be a 90 degree one for smoothness, or a flat plane one.

With the softer focus of a GT car, I would assume the F149 will get a 90 degree crank, like the Maserati and Alfa Romeo cars.

 

I have got to get me a new exhaust!! Our t sounds like a cadillac at idle. Smooth and quiet as kitten. Of course, under a load it comes alive.

 

Even in today's fuel injected world, the intake adds an important layer of sound to the overall experience. Like taking out the cello section in a symphony, what is there sounds good but not complete without all the parts in place. Cliche I know, but still a valid analogy.

I don't think any company puts more work into engineering the sound of their cars more than Ferrari.

 

Yes. Those are referred to as 180 degree headers.

 

Well I'll be a monkey's uncle. I just assumed because of the Ferrari development... but clearly not! You just killed my interest in Maserati by the way

I am such an exhaust note junkie, I would not buy a V8 Ferrari that did not have that flat crank sound. Take the CS: the exhaust note exemplifies the very essence of that car. Without it, it would not be the same.