Horsepower of the engines.

[Tommy Cookers]

the first 3 engines in the list were presumably run on fuel limited to the same Octane Number as road fuel
the last is being run on fuel without limit of ON (unlike 1958-2013 F1)
it would be less efficient if limited to road fuel ON (like 1958-2013 F1) as a reduced CR and/or boost would be necessary

and its efficiency can only be correctly represented by disregarding any power drawn from the store ES
stored energy is (mainly) energy that has already been counted as so-called 'sustainable power' output
(ie crankshaft power physically combined with whatever mu-k power is coming directly 'real-time' from gu-h power)
adding to this output power from stored energy is clearly double-counting and so is fraudulent
fraudulent as a statement of engine efficiency anyway

doesn't the Merc 40-43% efficiency mean 40% fairly accounted and 43% accounted by including stored energy ?

[Sixbarboost]

Plus 40% I seriously doubt, how can we know that?

[gruntguru]

Plus 40% I seriously doubt, how can we know that?

Nothing can be "known" with absolute certainty but Toyota openly claim 38.5 for the current Prius and 40% for the next generation. http://www.greencarreports.com/news/109 ... oyota-says

There are some reports (from Toyota) claiming over 40% (something around 42 from memeory) from engines they have developed for the Prius program. The 42% was turbocharged but it looks like they are going for the cheaper NA option.

[gruntguru]

the first 3 engines in the list were presumably run on fuel limited to the same Octane Number as road fuel the last is being run on fuel without limit of ON (unlike 1958-2013 F1) it would be less efficient if limited to road fuel ON (like 1958-2013 F1) as a reduced CR and/or boost would be necessary.

So it would be logical to assume significantly higher TE than the Prius.

and its efficiency can only be correctly represented by disregarding any power drawn from the store ES
stored energy is (mainly) energy that has already been counted as so-called 'sustainable power' output
(ie crankshaft power physically combined with whatever mu-k power is coming directly 'real-time' from gu-h power)
adding to this output power from stored energy is clearly double-counting and so is fraudulent
fraudulent as a statement of engine efficiency anyway

Exactly. Which is another reason that Mercedes claim of 40+% almost certainly does not include stored energy.

doesn't the Merc 40-43% efficiency mean 40% fairly accounted and 43% accounted by including stored energy?

It would be dishonest to include stored energy and use the word "efficiency".

If Toyota can release a road car (next gen Prius) with 40% efficiency on 91 RON, why is it so hard for folks to believe that Mercedes can be significantly higher than that given:
- The lack of financial constraint on engine construction
- The superior fuel available
- Turbocharging (worth 1 or 2% TE on the Prius lab engines)
- Compounding (worth 3 or 4% TE)
- Mercedes (Prof Webber) claim of 40+% was made in 2014. Current engines are clearly better.


There are very few minuses to balance the above list:
- Specific power is much higher
- RPM much higher
- Cylinder dimensions virtually spec.

Mind you, those 3 items didn't stop Honda RA168e achieving 32% TE despite:
- 30 year older technology
- PFI not DI
- No stratified charge
- No compounding
- Boost limit
- No lean burn - lambda was 0.98 (formula was "air flow limited" not "fuel flow limited")

My money says Mercedes are currently at approx 45%

[gruntguru]

This article discusses the engines Toyota were running in the lab a couple of years ago.

http://www.autoblog.com/2011/04/24/toyo ... xt-gen-hy/

One quote from the above link.
So far, Nakata claims that the engine development team has achieved a 42.4 percent thermal efficiency with Concept 1 and 43.7 percent thermal efficiency using the turbocharged, lean-burning Concept 2 design.

[wuzak]

the first 3 engines in the list were presumably run on fuel limited to the same Octane Number as road fuel the last is being run on fuel without limit of ON (unlike 1958-2013 F1) it would be less efficient if limited to road fuel ON (like 1958-2013 F1) as a reduced CR and/or boost would be necessary.

So it would be logical to assume significantly higher TE than the Prius.

and its efficiency can only be correctly represented by disregarding any power drawn from the store ES
stored energy is (mainly) energy that has already been counted as so-called 'sustainable power' output
(ie crankshaft power physically combined with whatever mu-k power is coming directly 'real-time' from gu-h power)
adding to this output power from stored energy is clearly double-counting and so is fraudulent
fraudulent as a statement of engine efficiency anyway

Exactly. Which is another reason that Mercedes claim of 40+% almost certainly does not include stored energy.

doesn't the Merc 40-43% efficiency mean 40% fairly accounted and 43% accounted by including stored energy?

It would be dishonest to include stored energy and use the word "efficiency".

If Toyota can release a road car (next gen Prius) with 40% efficiency on 91 RON, why is it so hard for folks to believe that Mercedes can be significantly higher than that given:
- The lack of financial constraint on engine construction
- The superior fuel available
- Turbocharging (worth 1 or 2% TE on the Prius lab engines)
- Compounding (worth 3 or 4% TE)
- Mercedes (Prof Webber) claim of 40+% was made in 2014. Current engines are clearly better.


There are very few minuses to balance the above list:
- Specific power is much higher
- RPM much higher
- Cylinder dimensions virtually spec.

Mind you, those 3 items didn't stop Honda RA168e achieving 32% TE despite:
- 30 year older technology
- PFI not DI
- No stratified charge
- No compounding
- Boost limit
- No lean burn - lambda was 0.98 (formula was "air flow limited" not "fuel flow limited")

My money says Mercedes are currently at approx 45%

So, you are suggesting 720hp using 43MJ/kg fuel?

In compounding mode only?

[Abarth]

The Cosworth simulation suggested 715 BHP in compounding mode, which translates in 190 g/kWh.

No Idea what fuel energy content they calculated.
43 MJ/kg would result in about 44%
46 MJ/kg in 41%.

46 MJ/kg @ 45% would result in 780 BHP without consuming further external energy (from ES), i.e. self sustained mode.

[bergie88]

Does anybody have an idea about how much power the MGU-H could generate from the turbo at max? So when all the energy in the exhaust gasses, normally lost through the waste gate, are converted to electric energy by the MGU-H? I could be wrong, but I've never seen calculations, or at least reliable numbers, about this.

If we know this we could determine how much power of the 120kW is delivered by the ES when the MGU-H is generating at its max, after which the total maximum power of the drivetrain can be calculated by using the compounding thermal efficiency.

[Gabii]

The calculation wouldn't be that hard to do, if you just want an estimate.

During my studies, we had a project : design a V6 satisfying the new 2014 regulations.

Obviously, as we had only 3 months and were working in duo, we only had to chose the major characteristics of the engine (bore, stroke, compression ration, etc).

We also had to design the turbocharging. The goal was to find the pressure in the exhaust before the turbine, so we could use it in our simulation on GTPower.

I started with a thermodynamics approach/ We knew the fuel limit, and knew approximately the range of AFR we would be using. From there we got the airflow, and then the compression ration needed. Then we could get the power needed by the compressor to give that pressure. From there we had the power the turbine needed to extract from the gases, which finally gave us the pressure ratio around the turbine. This was a nice attempt, but finally we opted for a much more down to earth approach.

We went on garett website, known for giving complete characteristics of their turbochargers, and chose the right turbo for our application. Easy from there to know of much flow we would deviate, and at witch pressure and temperature, making it possible to know how much power is "lost". This lost power is the power that would be harvested by the MGU-H.

Sadly, all the files are on my hardrive, on my other computer that just died, and frankly, i'm too lazy to redo the math. As soon as I find a way to get back my data, i'll come back with figures !

[Tommy Cookers]

by a long way, not all the exhaust energy is recoverable
are you assuming that the mu-k is acting at 120 kW whenever the driver desires ?
and btw .... are people assuming that the max efficiency will coincide with max power ?

2 years ago at Monza MM showed their mgu-h stated to be 70 kW

iirc one member posted Brayton cycle calculations of gu-h power at 46 kW based on 80% efficiencies of turbine and compressor
I recently posted in the TERS thread a source showing that the Brayton cycle under-represents the recoverable power
1940-50s precedent shows compounding power up to 18% of crankshaft power, this obtained without backpressure
and much more than this % with backpressure used by those assuming a Brayton cycle
from such % the compressor power (or some of it) should be deducted, but this was quite low
these precedents had relatively low CR, and so presumably would have higher exhaust energy for a given boost etc than our F1

[bergie88]

are you assuming that the mu-k is acting at 120 kW whenever the driver desires ?
and btw .... are people assuming that the max efficiency will coincide with max power ?

2 years ago at Monza MM showed their mgu-h stated to be 70 kW

iirc one member posted Brayton cycle calculations of gu-h power at 46 kW based on 80% efficiencies of turbine and compressor
I recently posted in the TERS thread a source showing that the Brayton cycle under-represents the recoverable power
1940-50s precedent shows compounding power up to 18% of crankshaft power, this obtained without backpressure
and much more than this % with backpressure used by those assuming a Brayton cycle
these precedents had relatively low CR, and so presumably would have higher exhaust energy for a given boost etc than our F1

1. No, but when we talk about maximum power of the complete powertrain the MGU-K is delivering 120 kW, which is a combination of power from the ES and the MGU-H. Next question is then if maximum powertrain power is reached when 1. the turbo is driven by the MGU-H (reducing ICE backpressure) and the MGU-K completely by the ES or 2. the MGU-H is regenerating at max with the rest of the 120 kW MGU-K power delivered by the ES?

2. I think so, because the ICE is fuel-flow limited, so maximum power (of at least the ICE) is reached at maximum ICE efficiency. If this is also the max efficiency/power of the complete powertrain? I dont know, these things could differ.

[Tommy Cookers]

Item 1
if I correctly understand your (ingenious) point
max power will be 1 but this is by a long way not sustainable, so temporary
2 might be less power than 1 but is still not sustainable, but much more durable than 1
imo
this point is analogous to the 1940s precedent (NACA research) - backpressure moves power from crankshaft to turbine

Item 2
surely not necessarily
do we know eg best efficiency % has not been achieved at 90 kg/hr fuel consumption giving 92% of maximum power ?
ie somewhat like the pattern of more conventional engines

[bergie88]

Item 1:
In the paper/presentation of professor Limebeer (if I am correct?) this point is also mentioned, which mode does deliver the most power? I think this could easily be calculated/simulated by the teams, but in our case (with much less information) it is unclear. Maybe the reducing backpressure mode is the qualifying mode Mercedes is always talking about? Btw, I think we can call mode 2 sustainable, because I cannot find a reason why it could not be used every single lap of the race.

Item 2:
You are correct, all components in the drivetrain have their efficiency map with the sweet spot, like in conventional engines. Therefore an important thing is to match all the components such that they are operated at their max efficiency when full acceleration is requested. In my opinion this is why Ferrari found so much power during the winter, their components (e.g. turbo size) where not perfectly matched.

[Tommy Cookers]

Item 1:
...... Btw, I think we can call mode 2 sustainable, because I cannot find a reason why it could not be used every single lap of the race.

afaik mode 2 you have described as having 120 kW of mu-k power from combining max available gu-h power and ES power
afaik no posters here believe that is sustainable ie continuously useable for the 60-70% of every lap that is 100% accelerator

genuine (and fake) KE recovery will be 2 MJ or less, this would contribute about 30 kW or less for the 60-70%
so your mode 2 demands 90 kW from the gu-h (afaik more than anyone here has suggested is possible)

however, the people who wrote the rules wrote them for a reason !

[gruntguru]

I believe the MGUH power is not far short of the 90 kW mentioned. 46 kW Brayton plus up to 18% of 600hp (up to 81 kW) from blowdown recovery. Current Mercedes reverting to individual runner exhaust is evidence of the value of blowdown energy.

Running at max sustainable evry lay (say 720hp) has at least two drawbacks.

1. 100 kg race fuel limit may be exceeded. (Tommy is the 60% @ WOT genuine? They only have enough fuel for 60 minutes at WOT plus 40 minutes coasting.)

2. Conserving fuel when possible allows reserves of fuel (to charge ES) to permit use of "qualy mode" when attacking or defending.