Mercedes Power Unit Hardware & Software

[Hoffman900]

Pretty sure two phase cooling is not allowed.

Sub-cooling of the charge could be done using the Porsche method which is essentially a vapour compression technique - boost higher than you need - intercool to near ambient temp - expand to the desired boost pressure and enjoy the associated temperature reduction. Similar to air cycle refrigeration used in some aircraft - with the exception that the expansion is done in a turbine for even lower temperatures and some energy recovery.

I would be surprised if they all aren’t doing that to some degree. It’s not exactly a secret or new.

And might be why the FIA specify that the temperature must be (ambient + 10deg C) in order to limit / prevent it.

The irony is that it isn’t secret, new, and it’s already used on street cars, and despite F1 parading itself as being super advanced. Sour grapes, sure.

This is also why it has to be taken as an average, and is not an instantaneous reading.

I believe Mercedes large plenum (inside geometry is ?) has given them more freedom to control this expansion phase. I bet the internal geometry doesn’t mirror the outside. NHRA Pro Stock guys do stuff like that to hide internal plenum designs, especially in the carburetor wet plenum days.

[PlatinumZealot]

Are heat pipes allowed?? Whis is basically two phase cooling. Low boiling point water in the plenum walls, gets heated by intake, the vapour moves to a heat sink where it is condensed and water returns to the chamber walls again.

Pretty sure two phase cooling is not allowed.

You are aright. The use of latent heat is banned, even if vapour compression is not used.

7.5 Cooling systems
The cooling systems of the power unit, including that of the air destined for combustion,
must not intentionally make use of the latent heat of vaporisation of any fluid with the
exception of fuel for the normal purpose of combustion in the engine as described in Article
5.10.3.

The Adiabatic expansion you mention seems to be allowed. Since it doesn't use any significant latent heat.

Sub-cooling of the charge could be done using the Porsche method which is essentially a vapour compression technique - boost higher than you need - intercool to near ambient temp - expand to the desired boost pressure and enjoy the associated temperature reduction. Similar to air cycle refrigeration used in some aircraft - with the exception that the expansion is done in a turbine for even lower temperatures and some energy recovery.

Yes, that method is a good one also agree that all the teams are probably doing it. I suppose a large throttle could also be used to expand the air if they don't want to fiddle around with acoustics too much like Porsche (imagine the maps for the VLIM - could crazy), I think some balance must be struck between the compressor work, and inter-cooler size (water cooling really helps here in qualifying) etc.

[Hoffman900]

I suppose a large throttle could also be used to expand the air if they don't want to fiddle around with acoustics too much like Porsche (imagine the maps for the VLIM - could crazy), I think some balance must be struck between the compressor work, and inter-cooler size (water cooling really helps here in qualifying) etc.

The problem with a large throttle is that the larger the throttle, the larger the percent open. It makes it really hard to tune, as most of the BIG horsepower / turbo US V8 guys have found.

There are ways around it with electronic throttle bodies and running the engine with fuel injection. This is actually how you dial in or take away engine braking (negative torque). It's a game of of leaving the throttle cracked open various amounts and tuning negative torque with the fuel injection / ignition timing maps. Also, as Kurt Trieb (KTM MGP engine designer / former BMW F1 engineer) lean burn characteristics will have an influence, and you want things to be super efficient at part throttle openings.

[PlatinumZealot]

I suppose a large throttle could also be used to expand the air if they don't want to fiddle around with acoustics too much like Porsche (imagine the maps for the VLIM - could crazy), I think some balance must be struck between the compressor work, and inter-cooler size (water cooling really helps here in qualifying) etc.

The problem with a large throttle is that the larger the throttle, the larger the percent open. It makes it really hard to tune, as most of the BIG horsepower / turbo US V8 guys have found.

There are ways around it with electronic throttle bodies and running the engine with fuel injection. This is actually how you dial in or take away engine braking (negative torque). It's a game of of leaving the throttle cracked open various amounts and tuning negative torque with the fuel injection / ignition timing maps. Also, as Kurt Trieb (KTM MGP engine designer / former BMW F1 engineer) lean burn characteristics will have an influence, and you want things to be super efficient at part throttle openings.

I meant throttle in the sense of a thermodynamic throttle, sort of an expansion valve.

[_cerber1]

The Italian version of Motorsport writes that MB can increase power in Sochi through different settings for the hybrid system. But, if that is not enough, they will take everything from the motor, sacrificing its reliability. All this is done in order to compensate for the shortcomings of the chassis, in the fight against RB.

[SiLo]

The Italian version of Motorsport writes that MB can increase power in Sochi through different settings for the hybrid system. But, if that is not enough, they will take everything from the motor, sacrificing its reliability. All this is done in order to compensate for the shortcomings of the chassis, in the fight against RB.

Are they insinuating that they will just take a power unit change at some point to run the engine harder to make up the gap to RB?

[_cerber1]

Are they insinuating that they will just take a power unit change at some point to run the engine harder to make up the gap to RB?

As far as I understand, there will be two stages of increasing power, the first should be in Sochi, this is an increase in productivity due to a hybrid system, which should not affect reliability. If this turns out to be not enough, they will take new motors, operating them in maximum modes, without regard to reliability.

[El Scorchio]

At some point in the season, it makes sense to do this as a final throw of the dice if necessary. It'll be interesting to see what they could actually do if they ran it at or slightly beyond their predefined tolerances and what difference it would make. I do wonder how close to that they are running now.

[SiLo]

I think RB having to take engine penalties at some point actually gives them this leeway to run the engines harder than they normally would. Maybe they see it as a better points haul to simply beat them on track in more races rather than try and big points gain in one race where RB take an engine penalty.

[Big Tea]

The Italian version of Motorsport writes that MB can increase power in Sochi through different settings for the hybrid system. But, if that is not enough, they will take everything from the motor, sacrificing its reliability. All this is done in order to compensate for the shortcomings of the chassis, in the fight against RB.

Are they insinuating that they will just take a power unit change at some point to run the engine harder to make up the gap to RB?

I was thinking about this, and I know I have used the term myself, but how would they run it 'harder'?
They cannot exceed the rev limit, or fuel flow limit or change gearing. Timing maybe? or would that be at the most efficient anyway regardless?

There are many ways to do it, but are there any without 'hitting' the rule.
Only thing that comes to mind is running a slightly more aggressive 'mode', which they would have to do for the whole weekend, but using what variables?

[hurril]

The Italian version of Motorsport writes that MB can increase power in Sochi through different settings for the hybrid system. But, if that is not enough, they will take everything from the motor, sacrificing its reliability. All this is done in order to compensate for the shortcomings of the chassis, in the fight against RB.

Are they insinuating that they will just take a power unit change at some point to run the engine harder to make up the gap to RB?

I was thinking about this, and I know I have used the term myself, but how would they run it 'harder'?
They cannot exceed the rev limit, or fuel flow limit or change gearing. Timing maybe? or would that be at the most efficient anyway regardless?

There are many ways to do it, but are there any without 'hitting' the rule.
Only thing that comes to mind is running a slightly more aggressive 'mode', which they would have to do for the whole weekend, but using what variables?

You can run more aggressive ignition timing which in and of itself leads to greater peek pressures (and faster pressure rises!) as well as an increased prevalence of knocking, all of which will put a greater wear on the engine.

[Big Tea]

Are they insinuating that they will just take a power unit change at some point to run the engine harder to make up the gap to RB?

I was thinking about this, and I know I have used the term myself, but how would they run it 'harder'?
They cannot exceed the rev limit, or fuel flow limit or change gearing. Timing maybe? or would that be at the most efficient anyway regardless?

There are many ways to do it, but are there any without 'hitting' the rule.
Only thing that comes to mind is running a slightly more aggressive 'mode', which they would have to do for the whole weekend, but using what variables?

You can run more aggressive ignition timing which in and of itself leads to greater peek pressures (and faster pressure rises!) as well as an increased prevalence of knocking, all of which will put a greater wear on the engine.

Thanks. But would that alone be worth the trade off? It would need to be balanced out and made available etc, so without being able to adjust any of the limiting parameters would it be 'usable'? (can not increase RPM, fuel flow etc? possibly useful via the electric machine?)

[hurril]

I was thinking about this, and I know I have used the term myself, but how would they run it 'harder'?
They cannot exceed the rev limit, or fuel flow limit or change gearing. Timing maybe? or would that be at the most efficient anyway regardless?

There are many ways to do it, but are there any without 'hitting' the rule.
Only thing that comes to mind is running a slightly more aggressive 'mode', which they would have to do for the whole weekend, but using what variables?

You can run more aggressive ignition timing which in and of itself leads to greater peek pressures (and faster pressure rises!) as well as an increased prevalence of knocking, all of which will put a greater wear on the engine.

Thanks. But would that alone be worth the trade off? It would need to be balanced out and made available etc, so without being able to adjust any of the limiting parameters would it be 'usable'? (can not increase RPM, fuel flow etc? possibly useful via the electric machine?)

I guess you could make a constraints equation with the gain of power multiplied by the length of time that is useful over the loss of durability multiplied by the remainder of usage time.

That ought to give an optimum points given the set of tracks to run together with some sort of measure of material in the relevant areas of the engine.

So made with even fewer parameters: how is the specific time performance affected by making the engine lighter.

An example: a stronger engine would very much improve the performance since that probably improves acceleration forces; the added weight would probably not hamper the acceleration. It will, however, affect the braking and the cornering performance to some degree.

So weight (of the engine) will affect close to the entire track but a faster acceleration only parts of it.

[Big Tea]

You can run more aggressive ignition timing which in and of itself leads to greater peek pressures (and faster pressure rises!) as well as an increased prevalence of knocking, all of which will put a greater wear on the engine.

Thanks. But would that alone be worth the trade off? It would need to be balanced out and made available etc, so without being able to adjust any of the limiting parameters would it be 'usable'? (can not increase RPM, fuel flow etc? possibly useful via the electric machine?)

I guess you could make a constraints equation with the gain of power multiplied by the length of time that is useful over the loss of durability multiplied by the remainder of usage time.

That ought to give an optimum points given the set of tracks to run together with some sort of measure of material in the relevant areas of the engine.

So made with even fewer parameters: how is the specific time performance affected by making the engine lighter.

An example: a stronger engine would very much improve the performance since that probably improves acceleration forces; the added weight would probably not hamper the acceleration. It will, however, affect the braking and the cornering performance to some degree.

So weight (of the engine) will affect close to the entire track but a faster acceleration only parts of it.

Thanks. I will have to spend some time pondering this as I am not the sharpest too in the box

[gruntguru]

The Italian version of Motorsport writes that MB can increase power in Sochi through different settings for the hybrid system. But, if that is not enough, they will take everything from the motor, sacrificing its reliability. All this is done in order to compensate for the shortcomings of the chassis, in the fight against RB.

Are they insinuating that they will just take a power unit change at some point to run the engine harder to make up the gap to RB?

I was thinking about this, and I know I have used the term myself, but how would they run it 'harder'?
They cannot exceed the rev limit, or fuel flow limit or change gearing. Timing maybe? or would that be at the most efficient anyway regardless?

There are several variables beyond ignition timing in play although it is difficult to predict the performance outcomes for each eg:
- Boost pressure. Changing this will change mass airflow through the engine, AFR, cycle temperatures, turbine/MGUH power requirements etc. It is likely that a small reduction in boost pressure will result in faster combustion (and knock risk) plus make more power available to the MGUH.
- Injection timing. Injection is broken down into multiple events during the intake and compression strokes. Varying the duration and timing of these events will change the shape of the stratified fuel cloud in the CC and also the AFR in the pre-chamber. This allows control of the rate of combustion and the relative temperatures of critical components, heat loss to CC and exhaust etc.