Mercedes Power Unit Hardware & Software

[Restomaniac]

You do realise that this Thread is about the technical Aspects of the Mercedes PU? Saying the PU looks like a Vacuum Cleaner adds nothing to the discussion. Nothing against a little fun, but 5 Posts about a Teletubbie Vacuum Cleaner in this Thread are just not justifiable regarding the Discussion that was going on.

You may want to modify the thread title then to avoid similar Issues. Nowhere are the words 'technical aspects' visible. Nor is it made clear that the subject matter is that tight in Turbo's origional OP.

[PhillipM]

There's a great big hint right at the top of the page, where it says "F1 Technical"

[PlatinumZealot]

Here are the picture(s) that I remembered seeing of the intake plenums:

http://www.f1i.com/wp-content/uploads/2 ... ine_FR.jpg

http://www.f1i.com/magazine/magazine-te ... a-vjm09/3/

The intake hole looks quite over-sized for the small size of the runners don't you think so as well?

[hurril]

The intake hole looks quite over-sized for the small size of the runners don't you think so as well?

It is rather large, yes. Let's play some measurements, shall we? What do we think the diameters are of a runner and that yellow (and red) cap?

[MrPotatoHead]

I think you'll find that there is a plenum that takes up the front half of the intake as shown there.
The runners go into the back of the plenum section not all the way to the front.

The size of the plenum opening looks about right to me for the runner size.

[hurril]

I think you'll find that there is a plenum that takes up the front half of the intake as shown there.
The runners go into the back of the plenum section not all the way to the front.

The size of the plenum opening looks about right to me for the runner size.

So do you think that the trumpets in there stop a good way before the cap? I always imagined that the space there houses the variable length trumpets.

[PhillipM]

I'd imagine most of it really is just a tuned plenum looking at the intake area and the size of it.

[stevesingo]

I think you'll find that there is a plenum that takes up the front half of the intake as shown there.
The runners go into the back of the plenum section not all the way to the front.

The size of the plenum opening looks about right to me for the runner size.

So do you think that the trumpets in there stop a good way before the cap? I always imagined that the space there houses the variable length trumpets.

There doesn't seem to be any visible mechanism for operating variable length runners.

Also, given the issues Honda had scaling up from single cylinder to full size, perhaps the split plenum is alleviating the the pressure wave cross talk from bank to bank.

[godlameroso]

The variable trumpets are bolted on the head itself, they have to be. I'm inclined to agree with Potato, the airbox bolts on to a flange, and the runners extend inside the airbox or retract as needed, so the actual runner diameter is somewhat smaller than the carbon airbox shows.

Just a thought, maybe the inlet of the airbox has a cable operated "camera shutter" style throttle?

[stevesingo]

The variable trumpets are bolted on the head itself, they have to be. I'm inclined to agree with Potato, the airbox bolts on to a flange, and the runners extend inside the airbox or retract as needed, so the actual runner diameter is somewhat smaller than the carbon airbox shows.

I don't think you would get any helmholtz resonance from a inlet tube within a tube. There will not be enough change in volume at the mouth of the runner.

Just a thought, maybe the inlet of the airbox has a cable operated "camera shutter" style throttle?

For what benefit? I imagine from a response point of view that the closer to the head the better.

[thedutchguy]

Interesting story by Matthew Carter (former team Lotus F1 CEO) on Missed Apex Podcast about Spa 2015, when Mercedes "gave Lotus a different engine mode" in order to have Grosjean finish ahead of Vettel. According the Carter, Grosjean told him after the race that the car had nevert felt like that (good) before. Lotus were neven 'given' that engine mode again.

You can watch the whole clip here: https://youtu.be/xBQA9eABkpc?t=27m10s

What I wonder is how Mercedes can 'give' or unlock an engine mode for the driver to use, when pit-to-car telemetry is forbidden? I understand how Mercedes can keep certain engine modes from their customer teams, but I'm a bit puzzled as to how they can choose to unlock them for a driver to use during a race when the car is on track.

[godlameroso]

The variable trumpets are bolted on the head itself, they have to be. I'm inclined to agree with Potato, the airbox bolts on to a flange, and the runners extend inside the airbox or retract as needed, so the actual runner diameter is somewhat smaller than the carbon airbox shows.

I don't think you would get any helmholtz resonance from a inlet tube within a tube. There will not be enough change in volume at the mouth of the runner.

Just a thought, maybe the inlet of the airbox has a cable operated "camera shutter" style throttle?

For what benefit? I imagine from a response point of view that the closer to the head the better.

Why put butterfly throttles? They're inefficient, better to have a means to regulate pressure in the airbox. The length of the intake trumpets are in relation to the intake ports of the head, or are you suggesting the entire airbox moves up and down?

[PlatinumZealot]

The individual butterfly is better for one main reason... Pressure charging the runners is many many times faster than having one single throttle body for the six cylinders. Think carefully about it and you will see.

As for the variable length runners. They are in the plenum. The openings to the two plenums are unusually large when compared to the 2014 engine. The VLIM are why. there is a little mechanism that the mechanics use to check by pushing their hand into the back of the plenum shroud in (2015 and 2016). That hole in now smaller, but it is still there. In other words the adjustment mechanism is now accessible only using a small tool. You can even see the connection to adjust the VLIM under the plenum. A small black electrical connector.

[gruntguru]

re "hole in plenum entry". The pipe feeding the plenum would be tapered, the idea being to gradually reduce the velocity as the air approaches the plenum. Ideal condition in the plenum itself is zero velocity and the transition from very high velocity at the compressor wheel tips to near-zero in the plenum should be as gradual as possible.

[stevesingo]

The variable trumpets are bolted on the head itself, they have to be. I'm inclined to agree with Potato, the airbox bolts on to a flange, and the runners extend inside the airbox or retract as needed, so the actual runner diameter is somewhat smaller than the carbon airbox shows.

I don't think you would get any helmholtz resonance from a inlet tube within a tube. There will not be enough change in volume at the mouth of the runner.

Just a thought, maybe the inlet of the airbox has a cable operated "camera shutter" style throttle?

For what benefit? I imagine from a response point of view that the closer to the head the better.

Why put butterfly throttles? They're inefficient, better to have a means to regulate pressure in the airbox. The length of the intake trumpets are in relation to the intake ports of the head, or are you suggesting the entire airbox moves up and down?

Doesn't need to be butterflies.

http://i968.photobucket.com/albums/ae16 ... -00175.jpg

If there is VLI, I think they will look similar to the arrangement in roon's sketch, with the length being changed by a telescopic element on the forward facing inlets.

If there is a mechanism in the plenum, it must be pretty neat and tidy.