Mercedes noise

[Nelso90]

I agree with modbaraban, even if the engine is totally faired in, 3mm of carbon-fiber isn't going to have a huge effect on the sound. Besides, noise from the actual engine (ie, sound coming through the engine case) is all high frequency, The noise you'd hear from that is like piston-slap, the ticking of lifters and cams, and gear noise.
Speaking of gear noise, I noticed a whole lot in that video where Hakkinen passes Schumacher near the busstop chicane at Spa. Anyone else notice this?
I've never heard it in any subsequent iteration of FO110 though, and to my knowledge, that engine sounded quite different as well.

[NickT]

I was reading the latest issue of Race Engine Technology and there is a big article about Renault's engine development using alternative firing orders to not only improve top end power but mainly to increase torque and drivability. This could be the cause of the different engine notes as the firing order has quite an effect on engine harmonics, particularly in the inlet and exhaust tracts.

As far as Big Bang motors go they have a very real place in Moto GP where they effectively run as V Twins and certainly have an advantage giving the tyre a chance to regain grip. However in F1 there are twice the number of cylinders to the effect is negated and then there are the associated problems DaveKillens outlined so clearly in his post.

[HKS]

If you look at the exhaust of a Ferrari




And the exhaust of a Mercedes engine



You might realise the difference in noise is because of the exhaust systems.

Or maybe Mercedes uses crush bend

[Conceptual]

Sounds like harmonic cancellation due to the "tuning" of the exhaust. The airbox may have some kind of resonance, but I dont think that it is making the sound in the first link.

I think exhaust construction is the pulprit here. Now the true question is that is it possible to use that system on a different engine and make any gains on HP output!

[HKS]

What I believe is Mclaren could have shorter length exhaust pipes, which might be causing the noise.

[Conceptual]

I havent read the exhaust regs in F1, but is it realistic to believe that the addition of SOUND, like a piezio "speaker", could influence the performance of an engine?

I find the mating of mechanics and harmonics to be VERY facinating. It only stands to reason that ALL movement creates vibration (harmonics) in some manner, so proper tuning of the primes would increase the efficiency of movement.

Reminds me an aweful lot of the work done by Edward Leedskalnin. He claimed to have the secret of how the blocks of the pyramids were put in place, and it all relied on harmonics and vibration.

Where is the link to F1 engines?

Chris

[gcdugas]

If you look at the exhaust of a Ferrari




And the exhaust of a Mercedes engine



You might realise the difference in noise is because of the exhaust systems.

Or maybe Mercedes uses crush bend

It looks like the Mac philosophy is to get the exhaust more "under" the rear wing before it exits the pipe for reasons of rear wing efficiency. Remember, Mac was the last team to go to top exhausts. I think they like their rear wing in cleaner air. Also guiding the hot exhaust further back has benefits for rear suspension components. It is accepted fact that tuned exhaust makes more power than "blewy pipes"; so all Mac has done is tune it a bit different. Perhaps you could go just one wave-length longer and maintain everything almost identically. (I have no idea how long the wave is so this may not be an option.)

[Ciro Pabón]

Wow, Conceptual, GREAT idea (I mean, speakers in the exhaust). I wonder how it would affect the flow. Perhaps you could pump the air while it's being sucked "backwards". Would it affect the intake as well as the exhaust? I can't google for it right now, but I will.

About the pyramids (sorry, total OOT) I've been intrigued for many decades by Herodoto's description of the "machines made of short wood beams", that the old guy described were used to lift the stones into place. I always thought the solution was in Herodoto's phrase, because I've found that EVERY description he made of things he had seen turned out to be true, even the "ships" interred with the pyramid.

A few months ago I bumped into the solution:

Small wooden objects found in New Kingdom deposits:


These objects coincide with the description of "wooden rockers" that Petrie (the original researcher of the Great Pyramid) found. Petrie was stumped (and many after him) because, how could you "rock" a stone efficiently and move it upwards with that things? Many people tried with bars and those rockers to "roll" the stone from side to side, using smaller stones to held the rock in place after every lateral "move" to no avail.

Now, how do you use them to move a 2 tons stone with "short wood beams"?

Easy, you tie four of them around a stone with a rope, like this:



Beautifully simple! That's engineering at its best, if you ask me. Way to go, Imhotep!

If you "roll" the rope around the "rollers" you even have a mechanical advantage! The larger the rollers, the larger the advantage. Besides, you can use two teams, one on each "wheel" to pull the stone. It works upwards and downwards. Notice the efficiency of the design: you could hardly use less wood.

Notice it works even for highly irregular blocks, like obelisks, just by adjusting the shape of the "rocker", which should be called a "roller". Rock and roll...

I proposed to use these things to move some slabs for a bridge recently, but the builder finally used a crane.

So, IMHO, no need for esoteric solutions. So sad that stone technology has been lost for centuries... The most wonderful things are right in front of our eyes, it's just that sometimes it takes time to be able to see them.

[NickT]

Ciro are you ok? Interesting post, a little off topic, but very interesting.

[Jersey Tom]

Well let's think here. Engine "tone" is going to be dominated by the firing of the cylinders. If you had a 4cyl engine firing 1-2-4-3 in a serial configuration, at 8000 crank revs per minute that's what, 16000 unique explosions minute, or 266.67 Hz.. which is what, a little over a concert C? Maybe close to a Db.

If you had the cylinders firing in parallel, like (1&3)-(2&4) you effectively cut the number of unique explosions by a factor of 2, and the engine tone would be one octave lower.

It's entirely possible McLaren is group firing cylinders which would make for a much lower tone (though I haven't listened close enough to onboards).

You can get "ringing" tones from the intake.. I've noticed that putting a big bell-mouthed velocity stack on a single intake for example made for a cool ringing tone with the engine sucking air through. It's possible there's also some of that, though I'd think the unmuffled sound of a V8 at 18000rpm would just deafen that out.

With regard to harmonic tuning.. there's some theory in exhaust design to that end. The simplest and probably most often talked about is "Helmholtz resonator" tuning of intake and exhaust systems. I say its mostly BS, particularly at the frequencies a GP car engine would operate at. Along similar lines is an impedance method.. where exhaust and intake runner geometry is likened to an electrical circuit of complex impedances and in theory you can tune intake and exhaust to have the same resonant and anti-resonant frequencies in order to really place your powerband. There may be something to that though I haven't seen enough tested proof.

My prefered method for exhaust tuning is wave reflection, as was taught to me by a well-known and very successful race engine builder of 35+ years experience. This is why you see stepped exhausts. I've found it works quite well, and that exhaust tuning has a much larger impact on powerband and engine VE than intake tuning.

But thats just my 2 cents.

[Ciro Pabón]

Ciro are you ok? Interesting post, a little off topic, but very interesting.

Well, first, I was trying to comment on Conceptual's phrase:

Reminds me an aweful lot of the work done by Edward Leedskalnin. He claimed to have the secret of how the blocks of the pyramids were put in place, and it all relied on harmonics and vibration.

I assume you worry about me because you think that the "roller concept" is my original idea and I'm a nut that claims to have cracked the secret to build the pyramids. I'd wish...

However, thanks anyway for your concern, you're a friend. I would do the same if I thought you put forward such preposterous claims without any backing, research or archeology training.

It's the idea of Dr. R. H. G. Parry, published in the Australian Academy of Technological Sciences and Engineering journal. Here is the link:

Rolling Stones

Mr. Parry's conclusion:

If µ = 0.25, the force required to roll a cylinder up a slope is 1 of 4 is only one-quarter that required to slide a block of the same weight. It is of interest to note in Figure 1 that in contrast to the sled the frictional force on the rolling cylinder acts up the slope and assists in raising it.

Here you have the full scale tests carried by Dr. Parry:

Rolling 2.5 tonne block up ramp with slope of 1 in 4.


Now, that it's a theory, but I think is more solid than the one of using sound waves to make the stones to float, the alternative proposed by Conceptual, don't you agree? I really think the guy hit the nail in the head.

Besides, the article is old (1997), I don't know why is not more popular, but, hey, this is a try.

I wonder how old is this technology: it could have been used in other megalithic constructions, some of them incomprehensible to modern engineers:



After all, humankind developed stone technology for, I don't know 1 million years, since the Stone Age. Most of the methods are lost, perhaps forever.

So, courtesy of F1Technical, next time somebody claims the pyramids were built by aliens, some kind of magic or the work of hundred of thousands of persons, you have a reasonable, perfectly logical engineering explanation.

I would like to mention that it's a feasible alternative in the third world (or anywhere) to the methodical use of hydraulic machinery, the only alternative we, engineers, offer today.

Allright, apologies for going OOT again. Last post on the issue, I'll now look for sound waves in exhausts and I'll be back, I swear. We have posted a lot about that here.

[Ciro Pabón]

Allr right, I have some time now. Some links:

MITRE vehicle-identification-by-sound system posted in the thread F1 engine noise?

Relevant quote: "Each cylinder in a vehicle engine is connected to the muffler housing through a pipe that can be thought of as an open-ended tube with a particular set of natural frequencies (like an organ pipe). The muffler is an acoustic bandpass-filter that amplifies some frequencies while suppressing others. This creates the characteristic pipe note valued by car aficionados."

Also from the same link: "Except at low frequencies, sound waves do not diffract well around corners. This means that if part of the vehicle frame blocks a line-of-sight path from a noise source (like the engine) to the observer, then that component is not heard. In order to account for small diffraction effects at lower frequencies, an empirical model was developed to account for sounds that would otherwise not be heard because of vehicle frame occlusions."

Conclusions: even if two engines are identical, the sound would vary if the exhaust pipe varies or the camera is mounted in different locations.

Second link: http://www.tunelab-world.com/rpmsound.html taken from the thread F1 engine output approximation by sound?

It's a simple software that "deduces" the rpm from the sound, developed for aircraft engines. The output I get is something like this:



In the same thread I mentione YMEC. The link: http://www.ymec.com/

Which gives you this output:



Third link: Pleae explain the variety of F1 engine noises? where there was an explanation about misfiring and valve overlap.

Fourth link: Car speed from engine sound

Here Reca showed us how to get the speed from the engine sound. Here is one of his results for a run by Fisichella (I think), RPM vs time:



From which he extracted the speed, assuming the gear ratios:



I don't know what software Reca uses, but the fact that the software is able to extract the basic frequency, tells me that the difference in sounds depends of the harmonics superimposed on the basic "piston firing". We'll have to ask him.

Finally, Reca posted recently a more sophisticated graph with the same work for an entire lap. I have no time to look for it, back to work.

[flynfrog]

There is a pretty good excerpt about the maca exhaust in "The Chariot Makers" by Steve Machett. It doesn't explain anything but talks about the speculation down pit road about there exhaust



Also Smokey Yunicks outlawed chevelle had a pretty trick set of pipes with holes drilled in them to get a secondary combustion in the headers

[flynfrog]

I forgot about this

tuning two stroke expansion chambers using water injection onto the pipes

http://www.factorypipe.com/t_pipetuning.php

[mep]

The link from flynfrog shows a quite good idear.
They don't whant to varie the pipes lenght, so they cool the gas
and get a changed sonic wave speed.
They say this would have the same affect as changing the length of the pipe.

But I think there could also be another effect conected with this.
The hot gas comes into the pipe. Now the temperature doesn't drop emidiatelly,
it goes constantly down and with the temperature the speed.
So the wave should get compressed because the beginning is slower than the end.
The effect is similar like the sonic wall in front of a fast moving airplane.
Whe now have a compressed pressure wave reflecting back to the engine and can
get a gain there.