How F1 V6 Hybrid Engines Sound when Turbo Wastegates Open!

I know it's hard to remember but in my previous Italian F1 GP 2016 and 2017 videos from Friday' free practice sessions I was intrigued by a quite weird sound change I noticed just a couple of times and characteristic of just a few teams/cars (Red Bull and McLaren in 2016. Red Bull, Toro Rosso and McLaren in 2017).
I asked you in the comments section and someone suggested it was caused by the opening of the two external turbo wastegates. I'm not an expert on the subject but it seems correct to me.

Why can you hear it only a few times and not always? Because of the MGU-H (also called e-turbo in production cars). It's the unit that is connected to the turbocharger and it's designed to spin the turbocharger at lower revs in order to reduce/cancel turbo-lag. It works in the same way of the MGU-K (Kers) so it can recover energy from the turbo, store it, and then use it to spin the compressor. When the hot gases spin the turbine, it also produces electricity that is stored in the battery and when the car accelerates, the electricity is used to spin the compressor, providing immediate power. It also works to adjust correctly turbo pressure in case the ECU detect an excess, reducing the compressor's rotation speed and harvest that excess in the form of electricity.
Due to the MGU-H, in modern F1 wastegates are probabily there more for a security reason than for a continuous and "traditional" use: since they're hydraulically actuated they open in case of problem at the MGU-H (which couldn't adjust turbo pressure) and maybe even when the batteries, to which the MGU-H is connected, are fully charged (even if this probabily couldn't happen).

If you remember, another reason why there are external wastegates is because FIA forced the teams to use them in order to increase and improve sound. But since MGU-H is controlled perfectly by most of the teams, wastegates are never used/opened...

So in this video I put together all the scenes I have from 2016 and 2017 where you can appreciate it and enjoy how much louder the V6 Hybrid engines could sound. I must admit I'm in love with that acceleration at 0:20, a lot better than the old V8s in my opinion (I said better, not louder...don't kill me XD). What do you think??

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- Event: Formula 1 Italian GP 2016 / 2017
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