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what exactly accounts for that sonorous ferrari wail?

Discussion in 'Ferrari Discussion (not model specific)' started by ewright, Feb 14, 2004.

  1. ewright

    ewright Formula Junior

    Nov 17, 2003
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    Ernest
    hi,

    i absolutely love the way italian machinery sounds at WOT. i was wondering what factors into making this mechanical scream that gives me the shivers? cam timing, exhaust tuning? thanks very much!

    ernie:)
     
  2. F40

    F40 F1 Rookie

    Apr 16, 2003
    3,227
    Small displacement engines that are very high reving... Along with cam timing and what not.
     
  3. Corsa

    Corsa Karting

    Nov 1, 2003
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    Peter
    The flat-crank in V8-engines do a lot for the sound.

    Ciao
    Peter
     
  4. ewright

    ewright Formula Junior

    Nov 17, 2003
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    Ernest
    thanks very much for the help! are flat-crank v8 engines specific only to ferraris or do some other manufacturers use this type of crank design as well?

    ernie:)
     
  5. JaguarXJ6

    JaguarXJ6 F1 Veteran

    Feb 12, 2003
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    I know one of the new VW engines does from reading a snippet a few weeks ago.

    Sunny
     
  6. 96impalaSS

    96impalaSS F1 Rookie

    Dec 8, 2003
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    Exactly what he said. Low displacement.
     
  7. Victory

    Victory Formula Junior

    Jan 28, 2004
    410
    The flat-plane crankshaft is the reason for the "wailing " sound. That's what most motor magazines explain the unique sound. That's the difference between Ferrari and the others. It's not the displacement.
     
  8. Peter

    Peter F1 Veteran
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    Dec 21, 2000
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    Its not a common use as it isn't very smooth running at idle, only in high-performance applications. Good for equal exhaust flow (separate headers - no need for cross-over or "H" pipes). The Cosworth DFV F1 engine used a flat crank. Domestic racing/hot-rod engines have also used it too.
     
  9. ewright

    ewright Formula Junior

    Nov 17, 2003
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    Ernest
    can you explain this further? i thought most of the ferrari engines are relatively large in terms of displacement (ex: 4-6 liters).

    ernie
     
  10. ChrisfromRI

    ChrisfromRI Karting

    Jan 28, 2003
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    I'm not sure that I understand what a flat plane crankshaft is, nor what other planes there are. I sure wish someone could explain this to me.

    As far as displacement goes, mine is a 3.0 liter 8 cylinder, thus the model number 308. It happens to be a Quattrovalvole, or 4 valves per cylinder, a head advancement over earlier 2 valves per cylinder 308 models. I think it sounds great at high RPMs with the stock exhaust. The 328, and 348 use the same model numbering concept, and thus have more displacement, and are also 4 valves for each of their 8 cylinders.

    I have always noticed that the 355 and 360 models have an even nicer crisper sound as you blip the throttle off idle though, and they are 5 valves for each of their 8 cylinders. Is there any explanation of the reason for that low RPM crispness? I always figured it was the profile of the camshafts.

    Kind Regards, Chris
     
  11. PSk

    PSk F1 World Champ

    Nov 20, 2002
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    A flat plane crank means that the crank is flat in one plane and is like a straight 4 cylinder engine. Thus Ferrari v8 engines are really 'just' 2 4 cylinder engines bolted together.

    Other v8's like GM and Ford, etc. have a much more complicated crank that has a different firing order ... hence the v8 burble or rumble from those engines.

    Another reason that flat plance cranks are used for more performance orientated engines is that exhaust scavenging is better as again you can build 2 4 cyl. exhaust extractor systems with no cross over pipes (have a look at a genuine Ford GT40 exhaust and the cross over comment will make sense).

    I have heard racing Rover v8's with a flat plane crank installed and it sounded beautiful ;), and wailed just lovely.

    As for Ferrari engines being low displacement ... well historically they used to be but I no longer agree with this comment. The Enzo is a huge motor at 6 litres and the F550 and F575 are not that much smaller, and the v8 Ferraris are slowly growing in size. We are up to 3.6 litres now thus 4 litres will come soon ... not small motors IMO.

    Anyway high revving motors scream as the cylinder pulses merge together. Listen to any Japanese motor cycle for example, and Ferrari motors do rev higher than the average engine.

    Thus we have the flat plane crank that creates the wail and the high revs means the wail turns to a scream at high rpm :D :D :D :D

    Pete
    EDIT: Okay I have tried to sketch a flat plane crank ;) :
     
  12. Auraraptor

    Auraraptor F1 World Champ
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    Sep 25, 2002
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    MO
    Ouch.

    F40 doesnt even have 3 liters....and just about the ENTIRE modern "Dino" line from the 308 GT4 to the 360 is sub 4L...
     
  13. Peter

    Peter F1 Veteran
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    Dec 21, 2000
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    A flat plane crank has the crank throws (the throws being the parts that the connecting rods attach to) at 180 degrees from each other. Thus, when viewing towards the nose of the crankshaft, the throws would only be on the left and right sides of the crank center. Typical American V-8's feature crank throws at 90 degrees from each other (this would mean when viewing towards the nose of the crank, you'd have one throw at the left, top, right and bottom sides of the crank center). V-6's and V-12's have the throws 60 degrees apart from each other.
     
  14. ChrisfromRI

    ChrisfromRI Karting

    Jan 28, 2003
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    Pete,

    Your sketch really helped me!

    Of course with my 90 degree V8 308 QV there is only one crankshaft for all of the 8 cylinders, so there are 8 connecting rod points all continuing in the same flat plane as the 4 you fit into your sketch.

    Any idea why the 355 and 360 have such a nicer crisper roar off idle as you blip the throttle, compared to the 308? I can only think it's the cam profiles, since everything else is so similar.

    Kind Regards, Chris
     
  15. ewright

    ewright Formula Junior

    Nov 17, 2003
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    thanks for all the information everyone!

    pete,

    do you know if it is possible to install a flat plane crank in a modern v8? (ex: bmw m5)

    ernie:)
     
  16. PSk

    PSk F1 World Champ

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    Glad it helped ... very crude but pictures do help ;)

    Er, not exactly as with (most) v8's 2 cylinders share a single crank big end journal, thus the crank looks very similar to a straight 4 cylinder. That is the beauty of v shaped engines, shorter and importantly so is the crankshaft and thus stronger ...

    I would have to agree that it probably is cam profiles, and maybe lighter flywheels, etc.

    If the BMW m5 v8 engine is a 90 degree v8 and you do not mind creating your own camshafts (remember the firing order will change) then the answers is yes. Does the BMW v8 already have a flat plane crank??? ... I do not know? I would have thought that BMW would already use the lightest and strongest possible crank design ... ;)

    Pete
     
  17. tvrfreak

    tvrfreak F1 Rookie
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    Besides the engine, there are a number of accessories which produce noise in the engine compartment--such as the alternator, AC compressor, engine cooling fan, etc. These soundwave components which vary with the engine combustion noise since they are driven by belts connected to pulleys which are being rotated by the engine crankshaft. Depending on the pulley ratios, these they may or may not produce a noise that is a harmonic of the engine. There's a few other components of noise as well, ie. the noise of the rubber tires rolling over asphalt, the air being disturbed as the car moves forward (or backward), and the gears in the transmission meshing and unmeshing. If the gears are straight-cut, as in reverse, you get the very noticeable whine. In addition to these major components of engine noise, some noise results from the turbulent air flow over accessories such as the radiator, radiator fans, and alternator. Finally, you can get lots of variation from the same noise source if the noise(s) reach you after being reflected off walls or other surfaces.

    Focusing on the engine note, the combustion of fuel in the engine cylinders is the major source of this noise. This combustion is an explosion like a gunshot, basically a sharp, flat sound or report. The exact nature of this report (how it sounds) is determined by the frequency, separation, and intensity of the explosions. These are determined by the cam profile, the size of the cylinder, the shape of the top of the piston, the compression ratio, the compression rate, the shape and location and position of the intake and exhaust valves, and the engine materials and their thicknesses. Additionally, how the explosion soundwaves reverberate through all the other structures in the engine bay, and the paths they follow before reaching your ears also influence the sound you hear or bass notes that you feel.

    Because there's multiple explosions happening each second, the noise pulses combine into a continuous burble or rumble or drone. The combustion(s) produces pressure pulses at a rate proportional to engine speed (the "revs"). In a four stroke engine, combustion in each cylinder occurs once every two engine revolutions, i.e. there are four pressure pulses per crankshaft revolution in an eight cylinder engine. As the revolutions increase, the frequency increases (more explosions per second) and you get the higher pitch sound or waaaaah, ie. the characteristic Ferrari wail.

    Additionally, noise is generated by the turbulent air flow from the air intake and exhaust systems. Engineers vary the diameter and length of the intake and exhaust systems so that standing wavesforms are created--this helps move the air through quickly, resulting in more air intake or better exhaust scavenging--this is how you get the term "tuned intake" and "tuned exhaust." These standing waves, or constant pulses, also contribute sound energy and form part of the engine's characteristic noise.
     
  18. ewright

    ewright Formula Junior

    Nov 17, 2003
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    Ernest
    i have to say thanks again (especially to TVR freak and pete!) for all the excellent explanations and drawings. I now have a far better idea of why ferraris sings at high revs

    ernie:)
     
  19. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    6,987
    The flat plane crank shaft is the key component. This allows for each bank to A) be in perfect ballance (primary) which allows B) each bank to have equal intervals of breathing which allows C) using harmonics in the pulse streams (intake and exhaust) to create more power.

    But Ferrari does not stop there:

    The intakes are short, straight, and direct, but the key component here is the throttles sitting in the exact center of the intake (plus velocity stack). This point has what is knonw as a pole in harmonic analysis terms. And having the throttle is the exact center of the intake allows the throttle to modulate the airflow without disrupting the harmonics. The single/dual throttle bodies of typical carrs cannot do this.

    To make use of the harmonic energy in the intake tracks, each bank is isolated in a helmholtz resonator that preserves the waves of the intake systems so that when a valve is ready to open, a high pressure wave is arriving at the back side of the valve just when the valve is set to open.

    Then on the exhaust side, each header is perfectly tuned to the RPM band where the engine make best power. In the power band, the header is tuned to have a negative wave arrive at the back side of the exhaust valve while it is still open. This negative pressure wave crosses the cylinder and arrives at the front side of the intake valves just as they open. The combined effects of the intake and exhaust resonance pulls fresh mixture into the cylinder even before the cylinder begins its downward journey.

    Finally, the cam is selected to work with the header and increase the wave effects in the intake system.

    In effect, its the whole package!

    But without the flat plane crank, about 50% of this harmonic energy could not be utilized because the pusle intervals would not line up in a harmonic way.
     
  20. ewright

    ewright Formula Junior

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    mitch,

    thanks for the extremely informative post!

    ernie:)
     
  21. 365boy

    365boy Formula Junior

    Nov 5, 2003
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    Don't forget the V12s.

    There has been a TV programme in the UK recently about a young chap learning to fly a WW2 Spitfire (V12 Rolls-Royce Merlin engine) - and inside the cockpit it sounds a lot like my Daytona.

    Which I thought was really cool...!

    John
     
  22. sjmst

    sjmst F1 Veteran
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    Damn, I was just about to say the same thing; beat me to it!
     
  23. 007

    007 Guest

    Feb 18, 2003
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    "What exactly accounts for that sonorous Ferrari wail?"

    The wail comes from the Ferrari owner as he hears the price of his/her 30K service, Then the note increases to a delightful shreik while carving up a twisty road in thier freshly serviced car, when he/she realizes it's the best money they have ever spent! :)
     
  24. Hubert

    Hubert F1 Rookie

    Jan 3, 2002
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    Wrong. Displacement has nothing to do with it; firing order, intake design, intake ports, intake manifold variations (ie., single stage v. butterflied intake design, etc) crank layout, exhaust system design, rigidity of the motor mounts, etc etc all add to the overall sound produced. (See Mitchs post.)
     
  25. PSk

    PSk F1 World Champ

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    Hmmm, Hubert I think he was refering to the fact that small displacement engines usually rev higher than larger engines ... definitely affecting the volume of sound produced, ie. working rev range makes a huge difference to the sound.

    Pete
     

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