Renault Power Unit Hardware & Software

[henry]

For torque and power to peak at the same RPM, the power must fall very sharply (faster than rpm falls) below the power peak. A 5% increase in power from 10,600 to 11,200 is consistent with a slight fall in torque so the torque peak is probably somewhere between the two speeds.

Absolutely true.
However, the ICE power is 10% lower at 10600 than at the power peak, not 5%.

I don't doubt your numbers henry (and acknowledge your disclaimers). 10% power decrease with a 5.6% rpm decrease is one very peaky motor. That is very unlikely for the engine configuration we have here:

- 4 stroke
- turbo
- same (regulated) fuel flow at both rpm
- variable length intake

I would be surprised if there is more than 1% or 2% drop.

The numbers I suggest could be wrong in a number of ways. The data could be wrong, not in mudflat’s research but in timing of speed and rpm. I made many assumptions and any of those might be wrong. If I find an idle moment I might try some sensitivity analysis.

It does seem unlikely that these motors would be peaky given the factors you quote.
However they are very different from previous art in terms of AFR and combustion processes. Is it possible that the conditions in the cylinder, swirl etc, would vary enough to vary combustion efficiency by a couple of percentage points. In a conventional engine it is possible to vary fuel quantity and timing pretty much every cycle but I don’t think the same is true of air mass. If they do vary the fuel the only way is down reducing power as a consequence even if they maintain efficiency.

[stevesingo]

regarding the fuel/cycle increasing at low rpm - if it didn't the ICE wouldn't idle
the friction/cycle ie frictional torque is rather constant ie independent of rpm
at idle rpm there's notable frictional torque, notable fuel consumption - and zero torque output

The fuel/cycle is a maximum mass allowed. When idling at 3k rpm the engine will not be using 32.5kg/hr allowed un the regulation 0.009*n+5.5.

[stevesingo]

Thinking again about where PU peak power may sit.

At 10500rpm+ we can release the energy from 100kg of fuel.

The energy is used to turn the ICE crank and excess from this is harvested to drive the MGU-H and stored for use later.

So, the more we burn the more we can use and store, so it seems obvious that for peak performance, 10500+ is where the ICE needs to be.

Above 10500rpm we have increasing friction, so ICE output will fall an this would be detrimental to car performance, to the point where a higher gear and lower rpm (<10500) would produce more power.

Can we not massage MGU-K assist to equal out the friction losses of running over 10500rpm, whist still utilising H harvest when we are using the most fuel?

[Big Tea]

Probably in the realms of fantasy here but, can the electric drive be used to 'overspeed' the compressor side of the turbo here to get the highest charge at the point of highest fuel without RPM relevance?

[PABLOEING]

Albert Fabrega ES
‏

Renault adelantará la evolución del motor para Barcelona. En Baku llegan evoluciones en bargeboards y alas para circuito baja carga.

[Thunder]

Would you mind to post an english translation? I mean i think it is about a Spain Update to the PU but it would be nice of you to post a quick translation for those not speaking spanish.

[baybars]

Abiteboul also has confirmed PU upgrade in Barcelona

Baku will mark the start of the next phase of our season push. We will debut some new chassis upgrades, specifically on the wings and bargeboards, which will be followed on the engine side in Barcelona

https://www.pitpass.com/61563/Renaults- ... an-preview

[Andres125sx]

Albert Fabrega ES
‏

Renault adelantará la evolución del motor para Barcelona. En Baku llegan evoluciones en bargeboards y alas para circuito baja carga.

Renault will speed up the PU upgrade for Barcelona. At Baku there will be bargeboards and wings for low DF track upgrades

[MrPotatoHead]

Renault powered cars have scored more points than either Ferrari or Mercedes up till now in the season... if that isn't interesting I don't know what is.

[NL_Fer]

They power 3 well funded teams, while Williams, FI and Sauber are still integrating the halo.

[AJI]

They power 3 well funded teams, while Williams, FI and Sauber are still integrating the halo.

And the races of 3 points scoring Ferrari powered cars were scuppered by wheel nuts

[gruntguru]

Thinking again about where PU peak power may sit.

At 10500rpm+ we can release the energy from 100kg of fuel.

The energy is used to turn the ICE crank and excess from this is harvested to drive the MGU-H and stored for use later.

Energy harvested from the MGUH is more often sent direct to the MGUK for immediate consumption.

So, the more we burn the more we can use and store, so it seems obvious that for peak performance, 10500+ is where the ICE needs to be.

Above 10500rpm we have increasing friction, so ICE output will fall an this would be detrimental to car performance, to the point where a higher gear and lower rpm (<10500) would produce more power.

Can we not massage MGU-K assist to equal out the friction losses of running over 10500rpm, whist still utilising H harvest when we are using the most fuel?

No more than we can at any other rpm. You only need to consider the total of crankshaft power plus MGUH power (AKA "self sustaining power"). This figure will peak somewhere slightly above 10,500 rpm. No advantage running higher rpm.

There may be a short term advantage running at a different rpm (or different operating point WRT ign timing, AFR, intake geometry, WG position, MGUH load etc) since the maximum that can be sent to the rear wheels is crankshaft power plus 120 kW MGUH. In other words the rpm for peak crankshaft power does not necessarily coincide with that for peak self-sustaining power.

In the long term however (eg not in traffic), you want to operate near peak self-sustaining output because that is where you get the maximum total energy per unit time (peak power) and also per unit fuel (peak efficiency)

[FPV GTHO]

Energy harvested from the MGUH is more often sent direct to the MGUK for immediate consumption

You're suggesting they are harvesting over 6MJ per lap then?

The rules limit 2MJ harvesting from the K to the ES, so the remaining 2MJ allowed in the ES has to come from the H. Full discharge from the ES to the K is more powerful than self sustaining from the H to the K, so if theyre sending more direct from the H to the K than from the H to the ES, it would have to be more than 2MJ being harvested outside of the ES. Minimum.

[stevesingo]

Thinking again about where PU peak power may sit.

At 10500rpm+ we can release the energy from 100kg of fuel.

The energy is used to turn the ICE crank and excess from this is harvested to drive the MGU-H and stored for use later.

Energy harvested from the MGUH is more often sent direct to the MGUK for immediate consumption.

So, the more we burn the more we can use and store, so it seems obvious that for peak performance, 10500+ is where the ICE needs to be.

Above 10500rpm we have increasing friction, so ICE output will fall an this would be detrimental to car performance, to the point where a higher gear and lower rpm (<10500) would produce more power.

Can we not massage MGU-K assist to equal out the friction losses of running over 10500rpm, whist still utilising H harvest when we are using the most fuel?

No more than we can at any other rpm. You only need to consider the total of crankshaft power plus MGUH power (AKA "self sustaining power"). This figure will peak somewhere slightly above 10,500 rpm. No advantage running higher rpm.

There may be a short term advantage running at a different rpm (or different operating point WRT ign timing, AFR, intake geometry, WG position, MGUH load etc) since the maximum that can be sent to the rear wheels is crankshaft power plus 120 kW MGUH. In other words the rpm for peak crankshaft power does not necessarily coincide with that for peak self-sustaining power.

In the long term however (eg not in traffic), you want to operate near peak self-sustaining output because that is where you get the maximum total energy per unit time (peak power) and also per unit fuel (peak efficiency)

My question is, is the added friction from 10500 to 11500rpm greater than the power gained from MGU-H harvest at 100kg/hr as opposed to friction at 9500-10500 but having less fuel to burn and presumably less waste heat to harvest?

Peak self sustaining output is entirely dependant on the relationship between ICE efficiency and MGU-H efficiency. Could there be a set of operating conditions where ICE efficiency could be sacrificed (such as running above 10500rpm) to enable better MGU Harvest?

Err, probably not. A 1% drop in ICE efficiency is 6kW. That would be what, 10% of MGU-H output?

[gruntguru]

Energy harvested from the MGUH is more often sent direct to the MGUK for immediate consumption

You're suggesting they are harvesting over 6MJ per lap then?

The rules limit 2MJ harvesting from the K to the ES, so the remaining 2MJ allowed in the ES has to come from the H. Full discharge from the ES to the K is more powerful than self sustaining from the H to the K, so if theyre sending more direct from the H to the K than from the H to the ES, it would have to be more than 2MJ being harvested outside of the ES. Minimum.

If the driver demands full power, ie the K is motoring at 120 kW, it doesn't make sense to be sending energy from the H to the ES. It is less efficient. It uses up some of the "per lap" ES limit.