F1 Engine Noise?

[manchild]

Noise level = difference between pressure in cylinder when ehxhaust valves open vs athmospheric pressure. That includes speed of opening of valves and diameter and lenght of exhaust as well as frequency/rpm.

I do not believe that's true...where have you heard that???

In second year at "engines and motor vehicles" class.

Every noise in the nature comes from pressure difference. For example; weapon silencers silence the sound of explosion by reducing the pressure and speed of gasses/pressure change. Same thing is with engine exhaust - aim is to reduce the pressure and to slow down the gasses before they reach the end of pipe (get in contact with atmosphere that will cause noise due to difference in pressure if one exists).

Noise from clapping doesn't comes because palms hit each other but because shape and speed of palms creates higher pressure zone between palms and once they hit each other noise appears as trapped air under pressure exits fast. Try hitting top of your palms to each other and there'll be no such noise because their shape traps almost no air.

[jgredline]

Noise level = difference between pressure in cylinder when ehxhaust valves open vs athmospheric pressure. That includes speed of opening of valves and diameter and lenght of exhaust as well as frequency/rpm.

I do not believe that's true...where have you heard that???

In second year at "engines and motor vehicles" class.

Every noise in the nature comes from pressure difference. For example; weapon silencers silence the sound of explosion by reducing the pressure and speed of gasses/pressure change. Same thing is with engine exhaust - aim is to reduce the pressure and to slow down the gasses before they reach the end of pipe (get in contact with atmosphere that will cause noise due to difference in pressure if one exists).

Noise from clapping doesn't comes because palms hit each other but because shape and speed of palms creates higher pressure zone between palms and once they hit each other noise appears as trapped air under pressure exits fast. Try hitting top of your palms to each other and there'll be no such noise because their shape traps almost no air.

Manchild
Yes to add a little bit more and I agree with you 100%, One of the most over looked part of engine building from a tunners point of view is measuring pressure in the tail pipe or in an F1 case end of the header.
While most of us have seen in pics of these F1 machines, o2 sensors and egt sensors or sensor, they usually will have a third fitting that will be connected to a tube and that measures pressure in PSI, much like boost.
To much pressure say 15lbs would mean there is much hp to be gained in getting it down to say 2-3 lbs. This could be done a few differant ways. Exhaust cam, header length, pipe diameter, valve diameter, overlap settings. By the other extreme if it has 0 psi, then there is no back pressure and you will have an engine that is down on power because it can't use the exhaust pressure to draw through the intake tract. This engine will be down on torque. In most cases this is caused by an exhaust system is plain to large and flows too much. This is why you just don't stick the largest headers on an engine.
What does all this have to do with noise?
An engine with zero back pressure will have a flat sound to it. Kind of like an old muffler. An engine with too much back pressure will sound very good at low speeds (out of corners) but as the revs go up it will go from sounding like a mad bee to a bee that has lost a wing. It will begin to flutter and sound as if it were floating valves. An engine that is just right say 2-3 psi of back pressure will have the highest level of ear peircing nosie of the three. In other words, when you see other teams measuring competitors ''noise'' they are measuring DBA. Decibles. Yes more noise generally means more Hp. This is how many teams know who has what under the hood. I don't know if this makes sense or not, but if not I will try and explain better.

[mep]

One of the things to consider is the sound frequency the engine is making.

I think the main sound is around 800-1000Hz(?) and there are harmonics above that, the human ear is most sensitive to sound at about 2800-3500Hz because of the length of the ear canal and the shape of the ear.

So its not that the F1 engines are making more sound than any other engine, its that they are making sound that is more easily heard, so it sounds louder

I think that makes sense.

I just found on a side that hte human ear hears sound of
a frequency of f= 4 000 Hz at the highest level.
It sounds louder than it's.

After hearing the first time the new V8 engines a few
weeks ago I was wondering why they sound much more louder than
the V10 engines I was used to hear.

So how is the effect of,
how much cylinders you have and at
what rounds per minutes/seconds your engine is running.

My experience from hearing says that the new V8s are louder.

[DaveKillens]

If you stood behind a Formula One engine of V-10 configuration running at 17,000 revolutions you would experience 1,417 pulses a second. With a V-8 at 20,000 RPM it drops to 1,333. The difference may seem slight, but the pulses would be spaced further apart, giving the impression of a stronger noise.
As well, with the newer V-8's, they spend a lot more time at full throttle and higher RPM. The V-10's spent a lot more time at lower RPM, with their greater torque.
Lastly, technology marches forward inexorably, each year brings exhaust systems capable of higher efficiencies, thus most likely louder. And a V-8 requires a different exhaust than a V-10, the pipes are of different length and diameter in the collector and final exhaust.

[mep]

I stoped writting my last post because I was out of time.
Now I'm going on.

My thought is

If you have a engine with one cylinder than you
have ever 2 tourns a bang.
So Frequency f= rounds per second/ 2

A 4 cylinder engine has every tourn two bangs.

A 8 cylinder engine has every tourn 4 bangs.
(Or maybe due to a special bank angle and timing 2 big bangs.)

A 10 cylinder engine should therefore have 5 bangs at one tourn.


20 000 rounds/minute = 333,33 rounds/second
17 000 rounds/minute = 283,33 rounds/second



V8 at 20 000 1/s

frequency f=333,33 * 4
f=1 333,32Hz


V10 at 17 000 1/s

frequency f=283.33 * 5
f= 1 416,65Hz

As you said a little drop in frequency.
But anyway far away of the 4 000Hz.
And there is a high frequency where the human ear stops to
hear. This frequency is to high for an engine but it's
a nice idear to produce one which is tourning so fast that
you couln't hear it.

I edited the numbers and get now the same numbers like you
dave but times the factor 1000.



The volume of the bang itself should be nearly the same because
it comes from the same amount of cubic volume of one cylinder.
3 Liter / 10 = 0.3
2,4 Liter/8 =0.3

[zac510]

If you have a engine with one cylinder than you
have ever 4 tourns a bang.

A 4 stroke has a 720 degree cycle, that is 2 'turns'.

[mep]

A 4 stroke has a 720 degree cycle, that is 2 'turns'


A little mistake I'll corect this.

[Ciro Pabón]

mep, pretty interesting post. But you could disagree on the conclusions about rpms related directly to the sound of the engine. The frequency you arrive to is the modulation of the "basic" bang, not the frequencies of the bang itself.

For example, if the bang were a pure sound at, I don't know, 5.000 hertzs, you will hear this same sound no matter how many times per second it happened.

The engine should behave like a speaker at 5.000 hertzs, only that it will "turn on" and "turn off" 1.433 times per second.

The final result should be a pure note at 5.000 hertzs, but with an staccatto sumperimposed (like an engine). The frequency of the stacatto (pop-pop-pop) would be that what you say, but the basic sound (pop) should remain unchanged. I do not know how to make it clearer. Am I wrong?

[mep]

You are right Ciro Pabón.

I try to say what you mean in a more simple way.

Imagine you have a piper with a flute.
If he is blowing in it you get a tone of one special
frequency.

Now he is blowing in it 1 333 times a second but you still
have the same tone and moreover more cleaner because more constand.
Like the pictures on TV.
So yes maybe the post I have written is totally superfluous, but I wrotte it to discuss about and I wasn't even the only one who was thinking
in such a way.

On the other side is the question if the fast opening of a room
which is under a high pressure will generate a sound which
has a (sinus kind) frequency?
Maybe it will be only one big pressure wave moving with the
speed of sound.
If we now add this to our basic frequency, than we will maybe
still have the basic frequency.
It may depend on the velocity of the pulses.

What I did could be a kind of approximation.
It works at high revs but not at low revs or the other
way round.

Does somebody know what kind of graph the opening
of a valve (burning of gas or a explosion) has?

[DaveKillens]

Let's also make the safe assumption that each cylnder, V-8 or V-10 moves the same volume of air each cycle. But the V-8's are definitely tuned for higher RPM. And just like the intake trumpet lengths, you shorten the exhaust pipes in the V-8 to optimize the exhaust pulses. So compared to a V-10, the individual exhaust tubes on each cylinder are shorter before they arrive at the collector. Then it would be safe to assume that because of shorter pipes, the sound is a bit louder compared to V-10's.

[Saribro]

the sound is a bit louder compared to V-10's.

Well, there's loudness, and there's percieved loudness. The 3 defining factors are volume, frequency and character. The first 2 are obvious, the last is somewhat more obscure and hard to define.
In the PC world, fan noise is an important factor to a lot of people. Now, you can have 2 totally different fans that register at the same volume, but the one with the higher frequency will usually be perceived as louder, because the higher pitch (commonly called 'whine', mostly on smaller fans) is a more noticable and annoying. For sound character, try to imagine for example one fan with a smoother, more continuous sound and another where a turbulent airflow creates somewhat of a 'growl'. Most people will consider the smoothsounding fan as less loud, because it is less noticable, although it would register the same amount of decibels.
I'd say the V8s have a slightly rougher, more agressive sound character than the V10s, but the biggest factor in perception is probably still personal preference. I can't comment on volume as I only watch F1 on TV, and they normalize.

[taleed]

I listened to the different engine sounds of Ferrari, Mercedes and other F1 cars and all of them sounded the same except for Renault. Check out this link and let me know if you hear a difference in the sound from near the beggining to the middle of the sound clip. Please also add why you think there was this sort of stuttering sound coming from the engine.

http://www.f1total.com/audio/audio.html?i=21

[manchild]

I listened to the different engine sounds of Ferrari, Mercedes and other F1 cars and all of them sounded the same except for Renault.

That's because Renault is exceptional

[taleed]

...I see that you like renault. I'm guessing cause they won last years championship and maybe this year too.
I was confused for a second when i heard the wierd noise coming from an F1 car because it sounded strange and thought that Kimi was driving.

But seriously. Maybe it's just me hearing stuff so could anyone explain why the wierd noise when their swaping gears...
Thanks.

0(^_^)0

[taleed]

...I see that you like renault. I'm guessing their exceptional because they won last years championship and maybe this year too.
I was confused for a second when i heard the wierd noise coming from an F1 car because it sounded strange and thought that Kimi was driving.

But seriously. Maybe it's just me hearing stuff so could anyone explain why the wierd noise when their swaping gears...
Thanks.

0(^_^)0