2014 Engines: Do they sound right?

[WhiteBlue]

Pretty cool:

But unrealistic. It disregards that you hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using its own respective exhaust. The V6 will run with the full frequency because both banks run into the one turbo. Even the turbo V6 of the past had two separate banks with one turbo each. Their sound is also of lower frequency.

[Blackout]

http://www.formula1guitar.blogspot.de/2 ... ngine.html

[WhiteBlue]

http://www.formula1guitar.blogspot.de/2 ... ngine.html

The commentary on the web page confirms that they have the wrong methodology.

[Pierce89]

Pretty cool:

http://www.youtube.com/watch?feature=pl ... kGdU#at=97

Extremely cool idea.

[piast9]

That is not entirely correct. The sound does depend on firing order, V angles etc. But in a flat 4 engine 2 cylinders doesn't fire at the same time. In a flat 4 engine one cylinder fires every 180°. Just as an inline 4.

You're right. I was misled by nice Subaru rumble but it appears it's just due to the firing order - here's an explanation: http://www.rahul.net/ddoudna/Subaru/

[xxChrisxx]

That is not entirely correct. The sound does depend on firing order, V angles etc. But in a flat 4 engine 2 cylinders doesn't fire at the same time. In a flat 4 engine one cylinder fires every 180°. Just as an inline 4.

You're right. I was misled by nice Subaru rumble but it appears it's just due to the firing order - here's an explanation: http://www.rahul.net/ddoudna/Subaru/

The rumble of the Subaru is because of unequal length headers introducing half order content.


An order is how frequently something occurs per revolution. So for example with an engine and a crank shaft. The crankshaft obviously rotates once per revolution.

So at 600rpm it has a frequency of (600/60) = 10Hz.
At 1200rpm it has a frequency = 20Hz.

2nd order is something that happens twice per revolution, in the case of a 4 cylinder engine this is the cylinders firing.
Firing order is usually by far the most dominant harmonic. 4th order is the 1st harmonic of 2nd, and so on.

2nd order would have a frequency of
600rpm = 600*2/60 = 20Hz
1200rpm = 1200*2/60 = 40Hz.

Half order is something that happens every 2 rotations, which corresponds to a specific cylinder. Cylinder to cylinder variation would give half order content in the sounds you hear.

http://www.vibratesoftware.com/html_hel ... htm#Normal Engine Vibrations Chart



Inlet and exhaust headers (exhaust are more important for noise), are just like a musical instrument. It plays a certain note depending on it's length. With equal length headers, every pulse from firing will 'play' the same note. So you get a very tonal sound, as the combustion events are equally spaced.

Unequal length headers introduce cylinder to cylinder variation in the note played. You will still get the tone from the engine firing (2nd order), but you also get frequencies introduces of orders 0.5, 1, 1.5, 2, 2.5 etc. This gives a characteristic burble.


The thing is it can get very tricky, very quickly and you can engineer noise in and out using the exhaust. Playing with phase, resonators etc. And indeed having two separate exhausts, meaning you treat each bank separately.


EDIT: Further to this, for an engine you don't hear the 1st order. 1st order noise/vibration is only heard when there is an imbalance in the crankshaft. Which would mean it would grenade itself before you could hear it.

First of all, note how the low frequency I talked about is the same for both sounds, as the revolutions regime for both engines is essentially the same.

[bhall]

Very funny that the noise lovers down vote people telling the truth on a technical forum. Actually it is a shame.

I did that, because this...

Pretty cool:

But unrealistic. It disregards that you hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using its own respective exhaust. The V6 will run with the full frequency because both banks run into the one turbo. Even the turbo V6 of the past had two separate banks with one turbo each. Their sound is also of lower frequency.

...is utterly absurd, but I didn't feel like starting an argument with you last night.

One does not "hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using [their] own respective exhaust," because - and this is vital - one hears the sound emitted from both exhausts!

I guess Popular Mechanics hasn't had any articles about sound propagation for you to binge upon and regurgitate back to the forum as gospel.

[xxChrisxx]

Very funny that the noise lovers down vote people telling the truth on a technical forum. Actually it is a shame.

I did that, because this...

Pretty cool:

But unrealistic. It disregards that you hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using its own respective exhaust. The V6 will run with the full frequency because both banks run into the one turbo. Even the turbo V6 of the past had two separate banks with one turbo each. Their sound is also of lower frequency.

...is utterly absurd, but I didn't feel like starting an argument with you last night.

One does not "hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using [their] own respective exhaust," because - and this is vital - one hears the sound emitted from both exhausts!

I guess Popular Mechanics hasn't had any articles about sound propagation for you to binge upon and regurgitate back to the forum as gospel.

You may be hearing both exhausts, but both are producing a tone of half the frequency. And two sources of a frequency does not give the same sound as one source of double the frequency.

The musical instrument analogy works here as well.

[rjsa]

You may be hearing both exhausts, but both are producing a tone of half the frequency. And two sources of a frequency does not give the same sound as one source of double the frequency.

The musical instrument analogy works here as well.

That's not exactly true. If both sources are perfectly locked in phase - what can happen on two cylynder banks within one engine but can't happen on two engines or distinct musical instruments - you will have one perceived highier pich sound signature.

[xxChrisxx]

You may be hearing both exhausts, but both are producing a tone of half the frequency. And two sources of a frequency does not give the same sound as one source of double the frequency.

The musical instrument analogy works here as well.

That's not exactly true. If both sources are perfectly locked in phase - what can happen on two cylynder banks within one engine but can't happen on two engines or distinct musical instruments - you will have one perceived highier pich sound signature.

Care to elaborate why you believe this to be the case? Rather than making a woolly statement that allows wiggle room. Lets agree a clear premise/scenario to explore.

[WhiteBlue]

Very funny that the noise lovers down vote people telling the truth on a technical forum. Actually it is a shame.

I did that, because this...

Pretty cool:

But unrealistic. It disregards that you hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using its own respective exhaust. The V6 will run with the full frequency because both banks run into the one turbo. Even the turbo V6 of the past had two separate banks with one turbo each. Their sound is also of lower frequency.

...is utterly absurd, but I didn't feel like starting an argument with you last night.

This is not only my point. It was made in 2011 by Rob White of Renault engine factory in a technical article I read. Perhaps I can find it for you. IMO it is a valid point that motivated the engine working group to specify a single turbo charger for both banks of the engine.
OK, I found a reference to the same interview, but it leaves out the technical explanation Rob White provided.
http://blogs.bettor.com/Rob-White-claim ... ews-a81096

White also claims that since the engines will use a single turbocharger and a single exhaust outlet, the sound of the engines is not going to change much and in fact, they are going to sound even better.

Here is another quote of the same interview. link here!

A single turbo will join together the six exhaust outlets and have a single tailpipe from the back, so that would tend to make the frequency of the engine note much higher than the frequency note from .. a V6 with separate exhausts.

I hope you recognize the expertise of the fellow. He certainly knows more about engine frequencies than your guitar player. And that was the gist of my post.

[Jersey Tom]

I think it'll be just fine.

If they end up sounding anything like the turbo V6's of the late 80's I'm sold. By far the best era as far as motor sound goes, IMO.

[rjsa]

OK, I found a reference to the same interview, but it leaves out the technical explanation Rob White provided.
http://blogs.bettor.com/Rob-White-claim ... ews-a81096

White also claims that since the engines will use a single turbocharger and a single exhaust outlet, the sound of the engines is not going to change much and in fact, they are going to sound even better.

Here is another quote of the same interview. link here!

A single turbo will join together the six exhaust outlets and have a single tailpipe from the back, so that would tend to make the frequency of the engine note much higher than the frequency note from .. a V6 with separate exhausts.

I hope you recognize the expertise of the fellow. He certainly knows more about engine frequencies than your guitar player. And that was the gist of my post.

All I could find was: "White also claims that since the engines will use a single turbocharger and a single exhaust outlet, the sound of the engines is not going to change much and in fact, they are going to sound even better."

And that's pretty far from a V6 with two pipes giving half the frequency.

[rjsa]

You may be hearing both exhausts, but both are producing a tone of half the frequency. And two sources of a frequency does not give the same sound as one source of double the frequency.

The musical instrument analogy works here as well.

That's not exactly true. If both sources are perfectly locked in phase - what can happen on two cylinder banks within one engine but can't happen on two engines or distinct musical instruments - you will have one perceived higher pitch sound signature.

Care to elaborate why you believe this to be the case? Rather than making a woolly statement that allows wiggle room. Lets agree a clear premise/scenario to explore.

Know the concept of linearity?

In mathematics, a linear map or linear function f(x) is a function which satisfies the following two properties:
-Additivity (also called the superposition property): f(x + y) = f(x) + f(y).
-Homogeneity of degree 1: f(αx) = αf(x) for all α.

Well, it applies to sound waves.

I wont ague that having one or two tail pipes will change the character of the sound. Also the presence of the turbo. But the half frequency assumption does not float.

[WhiteBlue]

I wont ague that having one or two tail pipes will change the character of the sound. Also the presence of the turbo. But the half frequency assumption does not float.

With other words the frequency is different (higher) for the 2014 turbo V6 than assumed by the guitar player. That was my main point when I said it was unrealistic. I don't really care enough for this issue to go into mathematics and figure it out. If you think you have the right frequency computed you can tell us the result. But I bet it will not be the one in the video.