Why do engines sound different ( read before writing me off as a retard)

Thread in 'Technical Questions' started by nissanr34cal, Jan 9, 2012.

  1. docwra

    docwra Active Member

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    Dont agree with a lot of what youve said mate, but that last one is ridiculous. You know those cars that Audi keep winning Le Mans with? You cant hear them. At all.
    And dont try and tell me its due to the exhausts, because if thats all it was then no-one would ever fail a noise test.

    I much prefer this explanation:

     
  2. silvertop

    silvertop der drifte schlag

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    i fitted a decat now my rb sounds like a wet fart =(
     
  3. m.d.

    m.d. Active Member

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    Erm. The reason you can't hear them is because of silencers and air boxes reducing the sound. Do you honestly think those engines would be as quiet as they are if you fitted a K+N to the inlet and a chav spec exhaust???
    I'm not trying to say a tuned engine sounds louder. Just better.

    I'm just trying to use my knowledge as a musician to try and explain why one noise sounds different to another and seeing as though the port of an engine acts very similar to an air instrument. I found it to be very relevant.

    Your air pump explanation although true doesn't really explain anything.
    If I take the air filter off my compressor and allow it to spin flat out how come it doesn't sound like a two cylinder motorcycle then???
    It's because it's the noise of the explosion inside the cylinder that has been altered by the shapes and lengths of the inlet and exhaust tracts to make the awesome or terrible sound you hear from an engine.
     
    #23 m.d., Jan 10, 2012
    Last edited: Jan 10, 2012
  4. 59bhp

    59bhp Member

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    As sound is just air vibration, whatever makes the air vibrate will affect the sound :)

    So as said pretty much everything lol
     
  5. 4_Stroke

    4_Stroke Member

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    LeMans Audis sound the way the do because they are diesels!
     
  6. Polo

    Polo Sr20 parts man!

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    Main contributions are, firing order, cam profile/valve timing, stroke, exhaust port size effecting gas speed. But yes just the simple things like valves, springs, manifolds etc can also make alot of differance..
     
  7. m.d.

    m.d. Active Member

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    Perfect example of how can profile effects noise is vTec. Nothing other than the cam shape changes yet the engine sounds completely different.
     
  8. Sam H

    Sam H Troll Dispatch

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    I was going to reply, but my vtec kicked in yo
     
  9. dale_b

    dale_b #DriftFactory

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    Agreed!



    Cock. THE perfect example of why a little bit of knowledge is a dangerous thing.
     
  10. chrisb

    chrisb Member

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    theres always one in the every class that enjoys a spirited conversation with the lecturer....

    ....the rest of us were happy doing the bare minimum to just about pass
     
  11. docwra

    docwra Active Member

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    Riiiiight, so every other racing car in the history of the world has been loud as fuck, but these ones have airboxes and silencers fitted. :rolleyes:
     
  12. m.d.

    m.d. Active Member

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    And as said. They are diesel too. Which makes them sound totally different to petrol race cars. they also need to run a cat and have turbos both of which deaden the sound a lot.

    If you seem to think you know so much about them then why don't you tell me in your own words why they are quiet and why engines make the sounds they do.
    Or is it that you actually know fuck all about the subject other than a quote you took from someone else. And are just trying to be clever and argue a point you actually know sweet FA about. :rolleyes:

    My daily drive civic type R has more power than some classic race cars.
    I'll use a ford pinto mk2 escort rs2000 as a good example as back in the day you could squeeze 200bhp from the pig iron lump in full race trim.
    So how come my civic makes almost no noise yet they are extremely loud.
    The answer is that the exhaust and inlet including the airbox on my civic are modern designs that allow flow but using harmonics and sound deadening techniques they can still achieve the BHP required but with no noise at all.
    Yet as soon as you lob on an aftermarket filter and de-cat strait through exhaust my civic is almost as loud as the escort.

    But going back to what stav said about the exhaust etc. the noise you are hearing is essentially the same but much quieter (muffled hence the name) as what the engine makes. Which is why an RB on a 3" single box stainless exhaust sounds totally different to a JZ on the same exhaust.
     
  13. Stavros

    Stavros Active Member

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    Is the Audi LeMans thing on about diesels? If so, of fucking course they are quieter, lol.

    They are revving to less than half as high and have turbos, which hugely silence the noise. Not to mention airboxes and silencers on top of that. They are quiet as fuck, using them as examples is ridiculous.

    Inlet and exhaust VOLUME is NOTHING to do with power levels FFS! You can have a 2500bhp 1ltr that is quieter than a standard car if you had the money and space!

    This is on about SOUND not VOLUME for fucks sake. People are slating MD but they the ones being stupid.

    F1 cars are crazy LOUD because they are unsilenced. They have that SOUND because of the total engine spec.
     
  14. nissanr34cal

    nissanr34cal Well-Known Member

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    i do the bare minimum to pass haha, the only reason i was talking to the lecturer was because i didnt wanna go to a maths lecture hahaha
     
  15. docwra

    docwra Active Member

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    But the Peugeots sound like racing cars, you can hear the ENGINES, not the exahuasts. With damn near the the same spec engines, airboxes, silencers, whatever. Regardless ........

    What I was actually disagreeing with was m.d.'s claim that tuned engines sound better. They dont, the LM cars prove that, if you want to extend the comparison the LMP2, GT1 and GT3 cars all sound different from each other, and none in my opinion sound as good as a standard Ferrari 458.

    Im no engineer, Im not making any bold claims about anything else but Im pretty fucking sure that the state of tune cant be used as a blanket explanation for how "good" an engine sounds.

    So to repeat, as its obviously in invisible writing first time round:

    I dont believe that the state of tune affects how good an engine sounds, certainly not as a generalisation. I do believe that everything that affects the airflow will though.
     
  16. Mau5

    Mau5 Member

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    Resonance is the main factor to creating a unique engine noise, silencers are just resonators used to create cancelling frequencies to make the noise different. so acoustics would have a fair bit to do with engine and exhaust noise
     
  17. Stavros

    Stavros Active Member

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    The tune and engine thing is deffo bollocks.
    Its all opinion anyhow. Screaming torquless Honda VTECs sound turd to me.
     
  18. Cowpatmatt

    Cowpatmatt Active Member

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    lol, surely thats down to the owner of the ears listening. I prefer the sound of pure performance rather then a £200,000 highway trumpet.

    So IMO a race spec engines sounds a shed load better then the road going version. So this means in my mind better state of tune = better engine sound. This better sound comes from cams, valves, heads, intake, exhaust ect.. all combined which all affect the airflow to make awesome ringing in my ear drums.
     
  19. docwra

    docwra Active Member

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    You would think so but Ive quite disappointed with GT Fezzas, at Le Mans and in Cup races - they sound quite flat and predictable rather than the noise you get outside Maranello every 4 minutes that makes your heart jump :nod:

    That said, GT spec Corvettes, Ford GT's and Lambo's more than make up for it. :D
     
  20. Dori-points

    Dori-points Member

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    Will this thread not die??? What are they teaching in college these days?? Engines all sound different because... Who give a flying f***
     

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