Mercedes Power Unit Hardware & Software

[godlameroso]

Regarding Mercedes super secret intake plenum rumors for next year. I wonder if it's a two stage/chamber plenum, where one chamber acts as a "boost pressure capacitor" and the second chamber feeds the VLIMs. This setup would create pumping losses for the compressor, but would eliminate the throttling inefficiency of of the compressor bypass. Perhaps ensure more predictable airflow into the ICE? It would also be noticeably bulkier than the standard plenum.

[godlameroso]

http://www.profblairandassociates.com/p ... lmouth.zip

[PlatinumZealot]

http://www.profblairandassociates.com/p ... lmouth.zip

Careful. Pdf can be used as virus containers.

[godlameroso]

http://www.profblairandassociates.com/p ... lmouth.zip

Careful. Pdf can be used as virus containers.

It's just an article detailing the benefits of bell mouth intake runners.

[stevesingo]

Regarding Mercedes super secret intake plenum rumors for next year. I wonder if it's a two stage/chamber plenum, where one chamber acts as a "boost pressure capacitor" and the second chamber feeds the VLIMs. This setup would create pumping losses for the compressor, but would eliminate the throttling inefficiency of of the compressor bypass. Perhaps ensure more predictable airflow into the ICE? It would also be noticeably bulkier than the standard plenum.

The restricted (28mm) Grp A rally cars of the 2000s used this principal. The boost pressures were really high, pushing against a 28mm restrictor where air speed were close to or at supersonic. The air, post restrictor was expanded through a 14deg (I think) taper into a large plenum to reduce temps. The lag associated with a large plenum volume was offset by anti-lag tech.

Musings to follow...

AIUI, the path to the expansion plenum needs to be sized (in terms of flow) to give a pressure drop on entry to the plenum, so the compressor is not compressing the air against the the individual intake tracts, but the restriction to the plenum within which the intake tracts live.

Given air demand from 10500rpm upwards remains the same (given the fuel flow limit) and the operating range of the engines is 9000-12000rpm it would make sense to have a plenum inlet flow capacity scaled for somewhere in that range, balanced against the turbine power required to drive the compressor against the restriction.

I'd be surprised if they hadn't already thought of this though.

[gruntguru]

The restrictor was located upstream of the compressor.

[stevesingo]

Quite correct, my mistake.

But, AIUI the concept was widely used in Grp A Rally.

[PlatinumZealot]

Quite correct, my mistake.

But, AIUI the concept was widely used in Grp A Rally.

Keep in the mind those Porsche plenums are likely for the NA engines. The expansion cooling is proportional to the adiabatic pressure drop as per the gas law. The expansion will only take place if the gas cannot fill the chamber fast enough... sort of unlikely with a highly boosted engine. Otherwise that compressor will cram as much air as it can into the space, and the pressure drop would actually be minimal.

[godlameroso]

Quite correct, my mistake.

But, AIUI the concept was widely used in Grp A Rally.

Keep in the mind those Porsche plenums are likely for the NA engines. The expansion cooling is proportional to the adiabatic pressure drop as per the gas law. The expansion will only take place if the gas cannot fill the chamber fast enough... sort of unlikely with a highly boosted engine. Otherwise that compressor will cram as much air as it can into the space, and the pressure drop would actually be minimal.

GT2 RS is turbocharged. The plenum was designed specifically for this car.

[PlatinumZealot]

Quite correct, my mistake.

But, AIUI the concept was widely used in Grp A Rally.

Keep in the mind those Porsche plenums are likely for the NA engines. The expansion cooling is proportional to the adiabatic pressure drop as per the gas law. The expansion will only take place if the gas cannot fill the chamber fast enough... sort of unlikely with a highly boosted engine. Otherwise that compressor will cram as much air as it can into the space, and the pressure drop would actually be minimal.

GT2 RS is turbocharged.

Yes i know porsche Gt2 is turbocharged. Didnt even read your wall to be honest. Haha.

Ok i have seen this before but forgot about it.

I still know there might be a catch from what I remembered....

OK rewatched it.

I see what you are explaining now. I thought you were saying the bulk volume would be cooled. That would be difficult without a throttling device of some sort.

So just regurgitating here; Porsche is pulse tuning such that the expansion in the wave takes place when the intake valves is open. So that the cooler part of the pulse gets pushed in. This effect they say happens only at high enough rpm. It essenially neutralizes the compressive pulse effect then reverses it.

Normally pulse tuning is done on the compression part of the wave such that the air is pushed in harder.

So porsche is trading some extra mass flow for lower temps. Ok. No magic there.

Alright.. So not a whole sale temprature drop, but localised. Still useful.

Cooler temps resulting in less chance for knock and thus cooler combustion. As seen in the video he showed a lower cylinder head temp by 20 degrees C. Fine.

Sure this "inverse pulse tuning" effect is more useful for hotter temperature charges such as in turbocharging.

I don't think this the same as throttling like in say an expansion valve, but according to them it make a cooler charge. cooler than the compressive pulse tuning.

Yes, prefectly reasonable to think F1 teams could be using this effect since they mostly operate at high rpms and high loads.

[gruntguru]

No need to "trade" any boost. Just turn up the turbo boost - the intercooler works harder - the expansion system brings boost back to the pressure you really want and cools the charge below the intercooler outlet temperature.

There is an even better way to do this using a turbine to expand the charge - cooling it further than just adiabatic expansion as used in the Porsche system. (air cycle refrigeration)

[tangodjango]

Nice article shredding some background on the lead-up to 2014 with direct quotes from Andy Cowell and John Owen

THE INCREDIBLE ORIGIN STORY OF THE MERCEDES F1 ERA

https://the-race.com/formula-1/the-incr ... es-f1-era/

[hurril]

Nice article shredding some background on the lead-up to 2014 with direct quotes from Andy Cowell and John Owen

THE INCREDIBLE ORIGIN STORY OF THE MERCEDES F1 ERA

https://the-race.com/formula-1/the-incr ... es-f1-era/

Imagine getting to read all about it at some point in the future about cylinder pressures, timing, challenges, etc. What they tried and their experiences etc.

[tangodjango]

"Mercedes’ chief designer John Owen tells The Race that not only was Cowell “very brave to indulge in the packaging” of the turbo-hybrid engine, he also had an ingenious but labour-intensive idea for the process.

“What he did is design three engines, effectively,” says Owen. “I think it weighed 250 kilos from memory, the first one. And it was an engine that was almost unbreakable. That was just there to understand performance development.

“He then made another engine that was very fragile, which was going to be the reliability engine, where they didn’t do much performance work.

“And then the third engine was kind of a marriage between the two of them, which is the one we took racing.

“Hats off to Brixworth for a very clever strategy there, I think they found a really, really good way of doing it. We heard other teams sort of tried to build their power unit for both performance and reliability and suffered the problems of lots of time spent with the engine broken and not being able to develop it.

“That was a really good call that they made. That’s why we were good on that side.”

Cowell sidesteps the responsibility for that decision, saying it was “not my plan, that was the plan that 20 to 30 leaders came up with at Brixworth and Brackley”. It was a key manifestation of a very, very well-integrated approach from Mercedes’ chassis and engine departments. But it was also a drain on human resources, requiring longer hours at the factory to make it happen.

The “unbreakable” engine shocked then-Mercedes boss Ross Brawn when he first saw it. Cowell’s priority was to ensure that the engine’s internals – pistons, conrods, bearing shells, etc. – were neatly detailed because they were of a style Mercedes wanted to race with. But everything ‘around’ it didn’t need to be pretty. The front cover, says Cowell, was so heavy it needed “several large men to lift it on”.

“When Ross saw it he was like…how are we going to fit that in the car?! How on this planet are we gonna fit that in the car?” laughs Cowell."

[DarthPlagueisTheVise]

Merc now can start their engine with the mgu-k!!!