what is responsible for Ferrari's unique engine note?

Joe,

Read this thread, it should give you the answers your looking for.

http://www.ferrarichat.com/forum/showthread.php?t=150801&highlight=ferrari+unique+exhaust+sound

Dan

 

No problem. It takes some time to figure out what words to use to get the results you are looking for. I'm glad you got your questions answered.

 

NO.... I am the worst thread searcher.... I put one word in serch and many threads show up that has the word in it but not related to what I am looking for..

 

Flat Crank and tuned exhausts, or so I've heard

 

Check out the animations in this thread (POST 12), shows the animations of a flat crank vs cross crank.
http://www.ferrarichat.com/forum/showthread.php?t=133101&highlight=flat+crank+animation

James in Denver

 

Posted on the old server:



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 can think of only one other object (other than the wail of a Ferrari engine) that would make a (otherwise) rational, intelligent, fully grown man part with >$100k to $$$millions over...

 

For what its worth. My previous employer had me buy him a 550. Seemed like every car on the market had a tubi exhaust. We wanted dead stock and finally got one sans tubi. When it arrived it was horribly evident that there was no exhaust note at any thing other than super high rpms. I think it was about a month before he ended up putting a tubi on it. So I guess that explains the exhaust note. As an aside, there is a collector w/ very significant (understatement of the year) collection of Ferraris in Cincinnati, who has on original Grandsport Vette w/ a traco buily big block, which is to this day the meanest sounding engine iI have ever heard (and I'm taking his GTO both 4 litre and 288 into consideration when I say this. Now that I have commited heresy I'll go do penance

 

The 550 is a touring car, so you're going to get more insulation from the engine sounds.

The 355 is the best sounding modern Ferrari I've heard. While I understand the alternate firing order, and flat plane crankshafts, I can't explain that. (And yes, I like my 328, and I like TRs, but when it comes to sound neither of those holds a candle to a 355 for whatever reason.) As posted in the reference thread, replacing the silencer/muffler isn't going to create a new sound -- just amplify or suppress the existing ones differently.

 

It might just be the 5 valve configuration, Bullfighter. That is unique to the 355, no?

I kind of feel like the multivalve system has almost as much to do with the sound as the flat crank: for sure that is the case with my ZR-1 Corvette (which has a 90 degree crank, but 4 valves per cylinder and separate intake runners and injector for each intake valve.

Makes a very unique "howl" in the WOT 3000-5000 range.

Now of course, for me, the best Ferrari sounds are the 12 cylinder cars - especially the 4 valve ones. And they don't "buzz" at idle.

 

Some really unique takes on 180 deg crankshaft (two 4 cylinder engines hooked together on a common crankshaft for better exhaust extraction) vs 90 degree crankshaft engines. The first has secondary imbalances and the second does not and is theoretically smoother. The first V8s used 180 deg crankshafts, such as the Hispano-Suiza V8s powering SPADS and S.E.5s in WW-I. The ninety degree crankshaft was not invented until a decade or more later, and was much smoother because of the lack of secondary imbalances. 180 degree crankshafts have always been associated with racing engines (or Ferraris) because the exhaust system was much more efficient at extracting exhaust gasses at high rpm. It does make a unique engine note. The secondary imbalances are compensated by careful design.

Ferrari street Boxer engines (BB, TR) were never true boxers where opposing cylinders fired at the same time to offset each other (the definition of a boxer engine) compared to true boxers like the BMW two cylinder motorcycle engines. The Boxers/TRs were 180 deg V12s with each cylinder firing at a 60 degree interval (60X12=720). Early Ferrari V6 and V12 engines had the cylinders at a 60 degree angle (some V6s at 120 degs and some V12 at 180 degs for lower center of gravity) for perfect balance (still secondary imbalances on the V6 engines), but the 1500cc F1 engines and the Dino 246GT deviated from this to allow more room for breathing by opening up the V to 65 degrees. Although this introduced additional imbalances, they were small enough to be engineered out. This 65 degree V was eventually adopted for the V12 engines as well to allow more room for the intake system.

The early 60 deg Ferrari V12s had a glorious exhaust note made up of high RPM, perfect balance and minimal exhaust systems. Late model Ferraris are 180 degree V8s or 65 degree V12s with careful attention paid to exhaust tuning, using high RPMs and multiple valves. They sound glorious because the factory wants them to sound that way and designs the exhaust to make sure it happens. Some are a little over quiet (my stock exhaust 575M, for example) at low revs, but still sound great when the second set of exhaust pipes open and the revs climb.

My C6 Z06s at 7000 rpms sounded great, but the sound was completely different from a Ferrari V8 or V12. Smaller displacement, higher revs, more valves, and the exhaust being tuned like a fine musical instrument make the difference. I love the difference.

Taz
Terry Phillips

 

mostly this
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Just about every new car has tuners for the Audio quality of their product.
This goes for interior noise as well . Or lack thereof. Clunk of doors. Everything. Exhaust included.
Road and Track had a fascinating article about it awhile back.