Mercedes Power Unit Hardware & Software

[dans79]

So how do you DRIVE the ICE harder in a sense and be able to sustain that power as a PU lap after lap? You have to charge the battery at some point right?

The flow between the ES and the MGU-H is unlimited. Thus if the ICE can withstand the extra wear and heat degradation, it can be pushed harder by recovering from and deploying to the MGU-H more aggressively!

[rogazilla]

So how do you DRIVE the ICE harder in a sense and be able to sustain that power as a PU lap after lap? You have to charge the battery at some point right?

The flow between the ES and the MGU-H is unlimited. Thus if the ICE can withstand the extra wear and heat degradation, it can be pushed harder by recovering from and deploying to the MGU-H more aggressively!

That part I get. It is the 'drive harder' part that makes no sense to me. Since the rev range doesn't change, the only difference would be increase compression? If the spec is locked, and I imagine the CR is already very high, how would you achieve that?

What's the consequences of higher CR? does it change the exhaust to that drives the turbo? If the ICE is more efficient then less heat to recover from MGU-H right? Less MGU-H then less flow between ES and MGU-H?

That's the part I am not understanding.

[dans79]

So how do you DRIVE the ICE harder in a sense and be able to sustain that power as a PU lap after lap? You have to charge the battery at some point right?

The flow between the ES and the MGU-H is unlimited. Thus if the ICE can withstand the extra wear and heat degradation, it can be pushed harder by recovering from and deploying to the MGU-H more aggressively!

That part I get. It is the 'drive harder' part that makes no sense to me. Since the rev range doesn't change, the only difference would be increase compression? If the spec is locked, and I imagine the CR is already very high, how would you achieve that?

What's the consequences of higher CR? does it change the exhaust to that drives the turbo? If the ICE is more efficient then less heat to recover from MGU-H right? Less MGU-H then less flow between ES and MGU-H?

That's the part I am not understanding.

It's a little more nuanced than that, they could run leaner, they could run richer, they can alter timing slightly, and they can do it by different amounts throughout the power/rpm curve.

[RZS10]

It probably goes all the way back to "how did quali modes work?" - It's also why i don't really understand how baffled some seem to be by the fact that the PU can be tuned to give a tenth or two in laptime at the cost of engine life when they were gaining at least half a second or sometimes even more than one second in laptime from Q2 to Q3 simply by using the party mode.

[rogazilla]

It probably goes all the way back to "how did quali modes work?" - It's also why i don't really understand how baffled some seem to be by the fact that the PU can be tuned to give a tenth or two in laptime at the cost of engine life when they were gaining at least half a second or sometimes even more than one second in laptime from Q2 to Q3 simply by using the party mode.

That's the thing... I thought I understood quali mode. What we saw at Brazil or in a sense if this rocket engine is as implied, its running in the mode through the race. Obviously could sustain for multiple laps and not just a single Q lap and then its slow/recharge lap. I thought I understood if you run higher power or run harder with ICE, you couldn't charge the ES to a level to last a lap? I just couldn't understand wrap my head around ONLY ICE change to achieve that.

[RZS10]

Wasn't the ICE usually the weak link that suffered the most degradation?

[Big Tea]

Wasn't the ICE usually the weak link that suffered the most degradation?

I have wondered about 'claims' that the Merc loses more power that the Honda with time.
What is the difference between that and the Merc getting a new motor boost and the Honda not?

It is (probably ) all about description.

[basti313]

Wasn't the ICE usually the weak link that suffered the most degradation?

I have wondered about 'claims' that the Merc loses more power that the Honda with time.
What is the difference between that and the Merc getting a new motor boost and the Honda not?

It is (probably ) all about description.

I think it does not loose power, they lose the strength of the piston.
They run it hotter, this is like classical chip tuning a Diesel engine. Or how Merc or BMW today run their Diesel engines...there are multiple power versions with either just software or turbo differences which share the same block and head. The only internal difference is the pistons, which are tuned to cost in terms of how they survive the combustion heat. Now if you go the way and buy a cheap engine and software tune it to the higher version...you will have no issue for quite some time until the heat changes the microstructure to a point where the piston junk breaks.

Same her for the piston:
They can run more heat for a certain time. Once they have used this time they need to reduce the pressure at the turbo charger and/or timing.
I even do not think the time is substantially depending on the mode they run, I think it is really "time".

Once Honda uses different materials or does not have the knowledge to even go into the time where they still have more strength you do not see the effect at all.
I think they tested exactly the time it takes until the piston looses strength with Bottas. Then in Monza they tested what happens if they run it hotter for some time.

[gruntguru]

The idea that any of the engines can be "run harder" and magically make significantly more power is a fallacy. Increasing compression, boost, ignition advance etc can only produce marginal increases at best.

[djones]

The idea that any of the engines can be "run harder" and magically make significantly more power is a fallacy. Increasing compression, boost, ignition advance etc can only produce marginal increases at best.

But even 4% more power is a lot on these engines…. 35bhp or whatever.

[gruntguru]

Agreed - but that 4% (if it is that high) probably comes at a cost of 90%+ reduction in engine life.

[basti313]

Agreed - but that 4% (if it is that high) probably comes at a cost of 90%+ reduction in engine life.

No, I do not think so. As above, they use the time when the microstructure of the piston is still hard to put more temp on it. They will not necessarily run shorter if they reduce the power accordingly to the change in the pistons.
And I do not get your first post. Of course every engine has a natural compromise of timing and lifetime once you start tuning it for performance.

[gruntguru]

And I do not get your first post. Of course every engine has a natural compromise of timing and lifetime once you start tuning it for performance.

You do realise we are not talking about "every engine" here? We are talking about an engine where a 4% power increase requires an increase of 2% in thermal efficiency!!! Bumping up the timing a bit aint gonna do it.

Very different to 99% of turbo race engines where you can increase MAP by 4% or so and "Bingo" there's your power.

[Tommy Cookers]

... Very different to 99% of turbo race engines where you can increase MAP by 4% or so and "Bingo" there's your power.

in F1 (additional to the usual combustion inconsistency giving the aforementioned ambiguity for ignition timing)

won't reducing the MAP at max fuel rate increase the short-term power ?
but reduce the reliability ....

because ....
the crankshaft power will be increased as reduced 'back pressure' outweighs the reduced 'forward pressure'
(remember some boost is available without BP)
the cooling system at design max won't respond (to in-cylinder temperature increase due to the reduced air charge)
starting a worsening undercooling situation - survivable if short-term but not a recipe for long engine life

[PlatinumZealot]

So how do you DRIVE the ICE harder in a sense and be able to sustain that power as a PU lap after lap? You have to charge the battery at some point right?

The flow between the ES and the MGU-H is unlimited. Thus if the ICE can withstand the extra wear and heat degradation, it can be pushed harder by recovering from and deploying to the MGU-H more aggressively!

That part I get. It is the 'drive harder' part that makes no sense to me. Since the rev range doesn't change, the only difference would be increase compression? If the spec is locked, and I imagine the CR is already very high, how would you achieve that?

What's the consequences of higher CR? does it change the exhaust to that drives the turbo? If the ICE is more efficient then less heat to recover from MGU-H right? Less MGU-H then less flow between ES and MGU-H?

That's the part I am not understanding.

The energy to and from the energy store has gone past limit returns. You are literally limited by regulations.

The heat input into the MGUH is unlimited however.

If your ICE can operate in away to make the same power while pumping more air, you will have way more energy to the MGUH. Alternatively if you can squeeze more energy from the fuel into the air you can extract more mechanical power to the pitsons and loose less to the cylinder walls.

This is very achieveable if detonation, and also lean flame stability can be controls because you see these engines are still detonation limited and are on the limit of running lean. New fuel formumations, new injections strategies, new piston and liner materials and shapes.. Lower friction parts.. Etc. All of these give more ICE power and /or you can run the engine harder for longer. It's like a domino effect.