Mercedes Power Unit Hardware & Software

[zibby43]

I’m honestly interested in how Mercedes is doing this regardless of the legality.

I’m no engineer but for adiabatic cooling by expansion you first need compression of the presumed plenum / pressure vessel right? So would this mean turbo pressure loss while building pressure in the plenum?

It is also rumored that the gains are during early acceleration and not so much at top speed. Could this specific early (temporary) gain explain why the average of the FIA temperature sensor shows normal readings of ambient temp +10?

And finally I also wonder why we have only first come witness these gains since Silverstone. The bulge has been there since reveal so why hold back?

Because it may have been obfuscated by the initial aero package Merc had to run all season prior to then.

They were running with a barn door RW in both Austria races. Since Silverstone, they’ve utilized less RW than RB at both circuits.

Alternatively, optimization/mapping may have been an issue.

[Hoffman900]

I believe Porsche claims to have a system on their turbo motors that drops in cylinder temperatures by 20* C. Their design requires more boost, but it’s offset.

So they might not necessarily be dropping it in the plenum, where the sensor is at, but in the cylinder (where it ultimately matters).

[dans79]

Some interesting bits per the technical regulations.

https://www.fia.com/sites/default/files ... -06-28.pdf

1.40 Engine Plenum

A pressurised vessel upstream of the combustion chamber containing air destined for
combustion. This vessel (or vessels) may be comprised of several components. Pipes, as
generally understood, conveying air from the compressor to the engine are not part of the
engine plenum.

5.6.8

Engine plenum (as defined in line 4 of Appendix 2 to these regulations) air temperature must
be more than ten degrees centigrade above ambient temperature. When assessing
compliance, the temperature of the air will be the lap average recorded by an FIA approved
and sealed sensor located in an FIA approved location situated in the engine plenum, during
every lap of the qualifying practice session, Sprint Qualifying Session, and the race. The first
lap of the race or Sprint Qualifying Session, laps carried out whilst the safety car is deployed,
laps with a time at least 20% greater than the fastest lap of the session, pit in and out laps
and any laps that are obvious anomalies (as judged by the technical delegate) will not be used
to assess the average temperature. The ambient temperature will be that recorded by the FIA
appointed weather service provider. This information will also be displayed on the timing
monitors.

Appendix 2 line 4

PU Engine air inlet system from
Engine plenum entry to cylinder
head (e.g. plenum, trumpets,
throttles)

As I read the above, All air destined for the combustion chamber must pass through the plenum.

The Teams can't put the sensor in some random spot in the plenum, as the FIA is mandating where the sensor has to be placed.

[b2bL44]

Some interesting bits per the technical regulations.

https://www.fia.com/sites/default/files ... -06-28.pdf

1.40 Engine Plenum

A pressurised vessel upstream of the combustion chamber containing air destined for
combustion. This vessel (or vessels) may be comprised of several components. Pipes, as
generally understood, conveying air from the compressor to the engine are not part of the
engine plenum.

5.6.8

Engine plenum (as defined in line 4 of Appendix 2 to these regulations) air temperature must
be more than ten degrees centigrade above ambient temperature. When assessing
compliance, the temperature of the air will be the lap average recorded by an FIA approved
and sealed sensor located in an FIA approved location situated in the engine plenum, during
every lap of the qualifying practice session, Sprint Qualifying Session, and the race. The first
lap of the race or Sprint Qualifying Session, laps carried out whilst the safety car is deployed,
laps with a time at least 20% greater than the fastest lap of the session, pit in and out laps
and any laps that are obvious anomalies (as judged by the technical delegate) will not be used
to assess the average temperature. The ambient temperature will be that recorded by the FIA
appointed weather service provider. This information will also be displayed on the timing
monitors.

Appendix 2 line 4

PU Engine air inlet system from
Engine plenum entry to cylinder
head (e.g. plenum, trumpets,
throttles)

As I read the above, All air destined for the combustion chamber must pass through the plenum.

The Teams can't put the sensor in some random spot in the plenum, as the FIA is mandating where the sensor has to be placed.

Thank you for digging this up. So the engine plenum is defined as a pressure vessel, so Scarb's tweet isn't far off the mark. Either a secondary vessel is contained within the plenum itself, or outside upstream of the plenum and downstream of the intercooler.

A reminder of the size of the plenum for the W12 in comparison to the W11, it's huge:



To quote the theory:

According to the theory of Red Bull and Ferrari, Mercedes manages to separate cool air from warm air for a while by cleverly routing the air between the intercooler and the plenum, thus gaining up to 20 hp in the initial phase of acceleration. Later, the compressor only pushes in warmer air and the advantage fizzles out.

As per the above technical regulations the temperature of the air is measured as an average over the distance of a lap. So, could it be the case that in the initial acceleration out of a corner, where this extra 20hp comes in, is where this "extra cooled" air is being released, followed by hotter air to balance out the average?

[Hoffman900]

Some interesting bits per the technical regulations.

https://www.fia.com/sites/default/files ... -06-28.pdf

1.40 Engine Plenum

A pressurised vessel upstream of the combustion chamber containing air destined for
combustion. This vessel (or vessels) may be comprised of several components. Pipes, as
generally understood, conveying air from the compressor to the engine are not part of the
engine plenum.

5.6.8

Engine plenum (as defined in line 4 of Appendix 2 to these regulations) air temperature must
be more than ten degrees centigrade above ambient temperature. When assessing
compliance, the temperature of the air will be the lap average recorded by an FIA approved
and sealed sensor located in an FIA approved location situated in the engine plenum, during
every lap of the qualifying practice session, Sprint Qualifying Session, and the race. The first
lap of the race or Sprint Qualifying Session, laps carried out whilst the safety car is deployed,
laps with a time at least 20% greater than the fastest lap of the session, pit in and out laps
and any laps that are obvious anomalies (as judged by the technical delegate) will not be used
to assess the average temperature. The ambient temperature will be that recorded by the FIA
appointed weather service provider. This information will also be displayed on the timing
monitors.

Appendix 2 line 4

PU Engine air inlet system from
Engine plenum entry to cylinder
head (e.g. plenum, trumpets,
throttles)

As I read the above, All air destined for the combustion chamber must pass through the plenum.

The Teams can't put the sensor in some random spot in the plenum, as the FIA is mandating where the sensor has to be placed.

Thanks, Dan.

The one thing that sticks out to me is the current PU concept is a mess if it needs rules as conflated as that. Oy.

I wonder where the FIA temperature monitoring takes place. Asphalt temps can approach over 130* F. I race bicycles now for fun, so I know how that feels.... you could be in a situation where the teams can need to cool 20-30* C from where the FIA is monitoring, which I get the average helps balance out.

[djos]

I've always wondered if any of the teams have tried implementing Thermoelectric cooling to boost the capabilities of the intercooler. Yes, you would have the extra heat from the TEC to deal with, but I'd have thought removing it from the compressed air would be beneficial to power and fuel economy.

[dans79]

Thank you for digging this up. So the engine plenum is defined as a pressure vessel, so Scarb's tweet isn't far off the mark. Either a secondary vessel is contained within the plenum itself, or outside upstream of the plenum and downstream of the intercooler.

Because it's part of turbo engine it's required to be a pressure vessel.

What I think Scarabs is trying to say is that at low rpm they are somehow closing it off on the trumpet/runner side so the turbo can temporarily over pressurize it. I have a hard time seeing this being practical, as even low rpm in an f1 engine is still several thousand rpm. Thus you have a very short period of time to over pressure the plenum, and you are doing it thousands of times a second.

I can't see their being a second pressure vessel, as the pressure and volume of air it would need to contain is not trivial. Not to mention you would need a secondary system to control it. I can't see the FIA being happy with that.

As per the above technical regulations the temperature of the air is measured as an average over the distance of a lap. So, could it be the case that in the initial acceleration out of a corner, where this extra 20hp comes in, is where this "extra cooled" air is being released, followed by hotter air to balance out the average?

The amount of air flowing through the plenum at low speed/rpm will be less as the engine needs less. Thus the air should by nature be cooler at low rpms as the cooling system has less air to cool, and will have slightly longer to cool it.

[dans79]

I wonder where the FIA temperature monitoring takes place. Asphalt temps can approach over 130* F. I race bicycles now for fun, so I know how that feels.... you could be in a situation where the teams can need to cool 20-30* C from where the FIA is monitoring, which I get the average helps balance out.

They are vague as hell about that, though this is buried in the technical regs as well.

6.5.2

No fuel intended for immediate use in a car may be more than ten degrees centigrade below
ambient temperature. When assessing compliance, the ambient temperature will be that recorded by the FIA appointed weather service provider one hour before any practice session
or two hours before the race or Sprint Qualifying Session. This information will also be
displayed on the timing monitors.
The temperature of fuel intended for use in a car must be measured via an FIA approved and
sealed sensor.

[Hoffman900]

I wonder where the FIA temperature monitoring takes place. Asphalt temps can approach over 130* F. I race bicycles now for fun, so I know how that feels.... you could be in a situation where the teams can need to cool 20-30* C from where the FIA is monitoring, which I get the average helps balance out.

They are vague as hell about that, though this is buried in the technical regs as well.

6.5.2

No fuel intended for immediate use in a car may be more than ten degrees centigrade below
ambient temperature. When assessing compliance, the ambient temperature will be that recorded by the FIA appointed weather service provider one hour before any practice session
or two hours before the race or Sprint Qualifying Session. This information will also be
displayed on the timing monitors.
The temperature of fuel intended for use in a car must be measured via an FIA approved and
sealed sensor.

Facepalm.

[dans79]

I've always wondered if any of the teams have tried implementing Thermoelectric cooling to boost the capabilities of the intercooler. Yes, you would have the extra heat from the TEC to deal with, but I'd have thought removing it from the compressed air would be beneficial to power and fuel economy.

The Peltier effect is horribly inefficient though, they would need to have a lot of spare electrical power they don't know what to do with.

[djos]

I've always wondered if any of the teams have tried implementing Thermoelectric cooling to boost the capabilities of the intercooler. Yes, you would have the extra heat from the TEC to deal with, but I'd have thought removing it from the compressed air would be beneficial to power and fuel economy.

The Peltier effect is horribly inefficient though, they would need to have a lot of spare electrical power they don't know what to do with.

Good point.

[Craigy]

I've always wondered if any of the teams have tried implementing Thermoelectric cooling to boost the capabilities of the intercooler. Yes, you would have the extra heat from the TEC to deal with, but I'd have thought removing it from the compressed air would be beneficial to power and fuel economy.

The Peltier effect is horribly inefficient though, they would need to have a lot of spare electrical power they don't know what to do with.

Good point.

They could feasibly cool things down in the pits before a quali lap to keep various components as cool as possible during the lap. It's not like they don't cool the fuel down to the regulation 10C below ambient as-is, for example.

I wonder if anyone has employed fuel formula to be dense past the fuel flow sensor and then heat it back up before injection like they did in the 1980s (although they were doing it that way in the 80s because toluene isn't all that great at vaporising unless it's pretty hot)

[Zynerji]

I've always wondered if any of the teams have tried implementing Thermoelectric cooling to boost the capabilities of the intercooler. Yes, you would have the extra heat from the TEC to deal with, but I'd have thought removing it from the compressed air would be beneficial to power and fuel economy.

The Peltier effect is horribly inefficient though, they would need to have a lot of spare electrical power they don't know what to do with.

Good point.

I bet the can produce more electricity under braking than they can store already tho...

So why not bleed to peltiers?

[nokivasara]

https://twitter.com/scarbstech/status/1 ... 72809?s=21

https://twitter.com/scarbstech/status/1 ... 77888?s=21

I'm not seeing how the first tweet calling it a pressure vessel would work. Air has to flow through it, even at low rpm.

Also the intake air temperature goes up if the pressure is increased. I must be reading it wrong...

[dans79]

The Peltier effect is horribly inefficient though, they would need to have a lot of spare electrical power they don't know what to do with.

Good point.

I bet the can produce more electricity under braking than they can store already tho...

So why not bleed to peltiers?

You need to feed them power all the time, and again their lack of efficiency can't be understated.