Engine wobbling sound

[spacer]

Amazing stuff, reca!

[mzivtins]

An F1 engine is limited the same as any other, by spark cut.

You can hear when the car is on the limiter from on board cameras. As well as the shift lights, the driver can hear it. Nowadays, the cars are geared to be close to the limiter in 7th, with DRS activated. The Red Bulls, and Mc Larens in particular, can be heard banging the limiter on straights. Re watch on board with Hamilton trying to pass Schumi at Monza last year....

Brian, I watched the video, and the revs to rise after the chatter, albeit the point between chatter and the shift point is close when revs rise that quickly! Remember the shift light activates 1500-2000 rpm lower than the limiter in 1st and 2nd gear to allow driver reaction time. The shift light stays the same if he revs the engine higher. At the first point of chatter you will see only the left part of the lights illuminate. Remember that we don't know what the lights are set to show in the starting phase, and the cars have multiple modes on the steering wheels.

Re watch it, but don't be fixated on the shift lights, and listen carefully. You have to 'feel' it....

Odd that... i'll just add another 500rpm to my redline tonight by adjusting the fuel cut in ECU

Not every engine works like that. Most i've known use a combination of fuel cut followed by ignition cut... soft limit to hard limit, some one or the other

But f1 cars im sure use some awesom tricks so their rev limit isn't as harsh as my firespitting overbored 1080cc v-twin motorbike that sounds like its shitting out valves when you bounce it on the limiter like a loon

[bill shoe]

Reca, thanks much. I did my own noise analysis and have a bit of info to complement your previous post.

The odd fluctuating sound on the Toro Roso is a 16 hz wobble. However, I was not able to clearly determine which of the following was going on--

1. Engine cutting in and out at a 16 hz cycle frequency (such as a spark cut-out), but maintaining essentially the same constant rpm.

2. Engine going up and down by a small rpm in a 16 hz cycle while continuously firing.

My noise software is allowing me to get good frequency resolution or good time resolution, but not both. The software is pretty good, I think it's just a limitation of the underlying sound file I'm analyzing.

The Renault file of Petrov's start was odd. I was expecting it to be easier to analyze since it was recorded on-board the car rather than from a stationary position. However, I was not able to make any determination about the wobble frequency, much less any idea if it was cut-out or rpm-fluctuation.

My intuitive impression for both files is that the engine is actually fluctuating rpm while continuously firing, but I have plenty of personal experience where the intuitive impression is wrong.

As a side note, in the Toro Roso accel run, I can see the exhaust tuning is very strong. When the engine is near redline the exhaust frequency is very strong. When the engine is not close to redline the main noise still occurs at the higher exhaust frequency due to 2nd-order noise hitting the exhaust tuned frequency. Basically, the exhaust likes to resonate at close to redline frequency whether the rpm is there or not.

[Red Schneider]

The Renault file of Petrov's start was odd. I was expecting it to be easier to analyze since it was recorded on-board the car rather than from a stationary position. However, I was not able to make any determination about the wobble frequency, much less any idea if it was cut-out or rpm-fluctuation.

I'm guessing the onboard microphone is crap compared to the one Brundle was holding.

[autogyro]

Few vocal mikes go anywhere near as low as 16hz, non I know of.
Most start from around 50hz.
Studio mikes, at least the ones I use start at 20hz.
So I dont see how you can conclude much.
Perhaps a few Months listening to live bands instead of rubbish MP3 files might help.

[rjsa]

Ok, now this is weird:

[Dragonfly]

Why?

[rjsa]

Can't you hear the really weird resounding by mid/end 2 seconds?

[Dragonfly]

It does not sound weird to me. Some change in engine mode with driver manipulating the throttle.
Does it prove anything?

[Saribro]

Anything will prove anything for people desperate to find something.

[rjsa]

Oh don't get me wrong, I'm the one who said the RBR was redlining 2 pages back. But I do hear a very odd sound in the last moments of overran engine into the turn. Like one of those fake exhausts kids put on bicycles.