What makes the Lambo exhaust "sound"....

Here ya go: http://en.wikipedia.org/wiki/Vibration

 

I'm a musician, a Lambo v-12 owner (400GT) and have designed several musical instruments. While I can't answer your question (I'm not an engineer!) I can say that the v-12 is the most perfectly balanced engine because of the explosions every 60 degrees. For example, it is so well balanced that my engine does not have a harmonic balancer...it doesn't need one, and never had one.

The shrill sound you are talking about, it's hard to tell because after 50 years I've concluded that you can't really talk about sound, you have to hear sound. Still, it's the v-12 sound specifically that attracted me to Lamborghini. It's like the opening of "Grand Prix" (the movie) there is only one way to get this specific sound, with a V-12.

So it has to be something different that what you're talking about if you're talking V-10. In general, the V-10 sound is much more "coarse" to my ear, not nearly as pleasing. I especially noticed that in the early Vipers -- just an awful and crass "truck" sound, which makes sense since it's a truck motor. (but wow, what a car!)

The Lamborghini V-12 -- like the Ferrari V-12 -- is a pure symphony of sound, it's absolutely beautiful in its smoothness.

When you get into the pipes and all that, I just don't know, except to say that if you mess around with the "tiny" 4-liter V-12 header pipes much you're basically bringing the system out of tune. They are designed specifically for that motor, which is short stroke, etc. (designed in the days when there were no computers, so obviously it can be improved upon, but not if you don't know what you're doing)

Now, as far as pitch and sound and all that, one of my best friends was an automotive engineer (he's no longer around) and he told me that where he worked (major company) every single piece of the machine -- and these were huge machines with lots and lots of pieces -- is tested to determine its exact sympathetic vibration. Everything has a mass, and everything can be vibrated "sympathetically" at its mass -- even huge bridges which come crashing down because they are vibrated sympathetically at their specific mass, either by soldiers marching or by winds. (this is not a precise definition, just an example)

So when you design any machine, like a Lamborghini engine, THESE DAYS (because they didn't used to do it this way) the engineers will know the mass of each part and its sympathetic vibration. By knowing this, they know all the overtone vibrations, because if something vibrates at 80 cycles, it also has overtones of 160 cycles etc.

All these numbers are fed into a computer so that they will know for a fact that the whole frickin' truck won't be vibrating like crazy at 65mph. A supercomputer can figure that out, I can't. I have to do everything by experimenting, otherwise known as trial and error (which is how these motors were designed in the 60s -- probably all by ear! Or at least initially by ear, then folks learned what worked and what didn't -- which is why Bizzarrini based his lamborghini v-12 design on the existing Ferrari v-12 design -- because he knew it would work. A lot of trial and error went into the original Ferrari V-12s, which were based on the original Packard V-12s....etc)

Trust me, I don't know what i'm talking about in detail, but basically that's the "broad stroke" version of all this. It's very complex, especially when you consider that something minor could be causing the engine to not "sing" but instead just be kind of listless. You want the engine to sing, which it can only do when all the vibrations are all working together.

Now...if a real engineer would show up and explain all this at a higher level, that would be great.

Cheers,

Fred

 

I think its the intake and Exhaust valves along with the Duration of the cams along with length of the exhaust pipes and the bends they have , thats the tune it makes , usally equal length and with a cross over or merg , I built a system for my GT4 it was totally old school Formula 1 sound , About a year ago I went to see a Testarossa that has a Tubi system , The store started her up and really goosed the gas a few times, I was really likeing it , The sound was really good , My Diablo although not on the road yet has a Larini system , 2 cats removed , very large pipes , nice even bends, 1 muffler , its kind of small , The sound is incredible and when I put the tailpipes on it will be sick,The Diablo has a incredible exhaust note , So I say its in the pipes,it starts in the combustion chambers via the valves and blows the music out the pipes like a instrument .

 

Old thread, but still pertinent.

I'm looking at buying a used R8 V10. It's not because I love the R8, but because I can't afford a Lamborghini or a 458. But I do love the V10 sound and from everything I have seen, the 5.2 V10 is an excellent engine.

The problem is that the R8 sounds like a BMW V10, not a Lamborghini V10.
And I've listened to almost every aftermarket exhaust for the R8 and none of them quite make the Lamborghini sound.

After doing some research, the closest I can figure is that inside the muffler section, near the inlet, there is a thin, angled steel plate that resonates around 420 hz and it is attached to another, longer plate that angles back in the opposite direction like an asymmetric V, facing the exit of the muffler can. The short plate sets up the resonant frequency and the longer plate then works like a speaker cone, amplifying the higher harmonics in the 420, 840 and 1680 and 3360 hz frequencies. Why these numbers? At 8,500 rpm, each cylinder is firing 70 times per second, which gives you the bass track of the engine. A bank of 5 cylinder will be 5 times higher frequency, or 420hz. Then the metal long plate will give off higher order harmonics at 840, 1680, etc. with a straight through muffler, you will hear mostly 70 hz and some 420 hz, but the higher harmonics will come from the wall of the muffler. But if the muffler isn't tuned to resonate at 420 hz, it won't amplify the higher harmonics.

For a better illustration, watch this video on how to make v10 sound with a beer can!
https://youtu.be/m40ZAfJb4f8

 

Another analogy of a straight through muffler vs one with a resonator plate is a bass drum vs a snare drum. With a bass drum, you just hear the low frequency pulse and to a lesser degree, the higher harmonics that develop across the drum head. With a snare drum, you hear the low frequency pulse and the higher harmonics, but the higher harmonics then cause the taught steel wires on the bottom of the drum (the snare) to resonate at the higher harmonic frequencies being produced by the head. Those wires then resonate at the higher frequency, amplifying that frequncy and then giving off their own higher harmonics that are 2, 3, 4 and 5 orders higher in frequency. The result is that a 200 hz harmonic in the drum head is able to make frequencies that are over 1000 hz.

So bringing it all together, these aftermarket muffler manufacturers need to cut open a stock Lamborghini muffler and see what is inside. If it has metal plates like what I am speculating, you should be able to measure the thickness and length of the metal plates and build aftermarket mufflers with the same size plates and get the same resonant frequencies and the same sound!

 

Actually, having non-merged exhaust creates more of a high pitched sound. The merged exhaust adds more bass.

 

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