2014-2020 Formula One 1.6l V6 turbo engine formula

[ringo]

The thermal efficiency of the otto cycle is very much temperature limited.
If it can be shown with using what we know are our intake temps, the exhaust temperature and combustion temperatures that must be below the thresholds of the materials being used in the engines, even using ideal cycles, then I would agree with 40% or whatever calculation is shown.
I'm not doubting gruntguru, but I wont buy it till it's demonstrated. I'm still of the opinion that the total efficiency is with the ERS.

40% of 46 kJ/g x 27.8g/s x 1.3hp/kW is roughly 650hp. So in some way the efficiency is there or there abouts, but we need proper numbers to accept this. As no team has come forward with a power figure.

Going by my power number, it seems to be 611/ (46x 27.8 x 1.3) = 36.7% , still quite high anyway.

For 588hp, 588/(46x 27.8 x 1.3) = 35.3% so you get the idea.

Looking at this alone, then I guess why it will be reasoned that these ICE are 40% efficient. but i'm not quite sure, as my calculations of 611hp are a theoretical cycle, with none of the empirical inefficiencies that exist in real life.

[wuzak]

I'm not doubting gruntguru, but I wont buy it till it's demonstrated. I'm still of the opinion that the total efficiency is with the ERS.

I think grunt is also including the ERS - but not the ES - in the efficiency equation.

That is, peak efficiency is when the ICE is operating with the MGUH/MGUK as a turbo-compound - self sustaining mode, as described by Cosworth.

There is no additional input from the ES - whose stored energy can be from recovered braking energy, the MGUH, the MGUK (dragging the ICE under acceleration) or the power station down the road.

It is hard to put a number on the amount of power the MGUH can deliver back to the MGUK. Cosworth's graphs from some time back suggested about 100hp - 75kW.

[gruntguru]

My understanding is the same, a Stratified Charge can only be used under light and moderate loading and not at high RPMs. A Homogeneous Charge (either stoichiometric or slightly rich) is needed at WOT for maximum power generation.

You can run lean (or even super lean), but you will not generate the same level of power as a homogeneous charge. There are no free lunches!

I keep being surprised by the number of posters who do not "get" how the curent F1 formula works.

What you are saying about a homogeneous charge being required for max power applies to an "airflow restricted engine" - where you are given an engine with a given size and breathing ability. (This is the traditional performance engine challenge.) When max power is required, you must add the quantity of fuel that makes the most power from the airflow you have been given to work with. This usually turns out to be a lambda ratio of about 0.9. If you attempt to do this with a stratified charge, the rich section of the charge will be richer than 0.9, the lean section will be leaner than 0.9 and combustion will not be ideal for max power. The answer is a homogeneous charge when running rich for max power on this category of engine.

The current F1 engines are "fuel flow limited". When max power is required the engine is operated somewhere above 10,500 rpm and 100 kg/hr of fuel is injected. Since the engines are capable of flowing far mor than the stoichiometric quantity of air, the engine developer now has a wide choice of how much air to add to this 100 kg/hr of fuel to extract the maximum power. With a traditional fuelling system capable of producing a homogeneous charge only, the best efficiency and therefore the best power will be obtained when about 10% - 15% excess air (lambda = 1.1 - 1.15) is added.

For a "fuel flow restricted engine with the possibility of a stratified charge", it will probably be more efficient to produce a mixture of 1.1 - 1.15 in the central burn zone and encapsulate that in some extra "fresh air" to eliminate wall quench and heat loss effects. This would result in a mixture which is still leaner.

You don't "get" f1. Its the same engineers as road cars but with less resources. They are not likely running fully sratified charges at 12000 rpm WOT. They're just not quite there yet.

You have misquoted me. I said " . . do not get how the current F1 formula works". The current formula is very different to any previous formula and a number of posters are still thinking in terms of Max Power AFR's around 0.9 (13:1). We no longer have a situation where the engine tuner varies the fuel flow to make maximum power from the air the engine is capable of breathing. Under the current rules the max power fuel flow is fixed at 100 kg/hr and the tuner varies the airflow through the engine until maximum power is obtained. Past experience shows that this will occur at an AFR of 1.1 - 1.15. IMO this is the richest mixture these engines will see on the racetrack. If the engineers are achieving any charge stratification at 10,500 the mixture will be leaner still.

Are they achieving stratified charge at 10,500?
Quite possibly. It hasn't been done on road cars yet because they don't need to. Road car fuel economy has very little to do with WOT efficiency (unless its a Prius or other hybrid where WOT operation is preferred and frequent). If a maker builds a performance road car or super-car they would be mad to ignore the full performance potential of the engine by running lean at WOT. All they have to do is add about 20 - 25% more fuel and the power will increase by 10 - 15%.

[Tommy Cookers]

...... Under the current rules the max power fuel flow is fixed at 100 kg/hr and the tuner varies the airflow through the engine until maximum power is obtained. Past experience shows that this will occur at an AFR of 1.1 - 1.15. IMO this is the richest mixture these engines will see on the racetrack ......

again ......
past experience means nothing here
with DI at 500 bar we do not need 10-15% surplus air for complete combustion of the fast-combusting race fuel
maybe 2% surplus air is sufficient

these engines need no more than 1 bar of compressor-added pressure to be filled with sufficient air to match the fuel rate limit
a 15% air surplus needs 15% more abs induction pressure (ie 1.3 bar added pressure) working on a 15% greater mass
ie about 30% more compressor work, costing gu-h recovery, more mu-h spoolup work, more friction and demanding more intercooling
ok, some of this extra compressor work is recoverable (we knew that)

but 10-15% surplus air is not needed for full combustion in 2014 F1
IMO

[gruntguru]

...... Under the current rules the max power fuel flow is fixed at 100 kg/hr and the tuner varies the airflow through the engine until maximum power is obtained. Past experience shows that this will occur at an AFR of 1.1 - 1.15. IMO this is the richest mixture these engines will see on the racetrack ......

again ......
past experience means nothing here
with DI at 500 bar we do not need 10-15% surplus air for complete combustion of the fast-combusting race fuel
maybe 2% surplus air is sufficient

Past experience is all we have. Your hypothesis that 500 bar DI changes the long established yardstick for best economy AFR is pure conjecture. You may be right but I would rather stick with established knowledge until your hypothesis is confirmed.

these engines need no more than 1 bar of compressor-added pressure to be filled with sufficient air to match the fuel rate limit. a 15% air surplus needs 15% more abs induction pressure (ie 1.3 bar added pressure) working on a 15% greater mass ie about 45% more compressor work, costing gu-h recovery, more mu-h spoolup work, more friction and demanding more inter cooling ok, some of this extra compressor work is recoverable (we knew that) but 10-15% surplus air is not needed for full combustion in 2014 F1 IMO

Why is your reasoning not applicable to gas turbines or even diesels? In both cases TE does not suffer as PR is increased well beyond that needed for stoichiometric combustion?

[gruntguru]

past experience means nothing here. with DI at 500 bar we do not need 10-15% surplus air for complete combustion of the fast-combusting race fuel maybe 2% surplus air is sufficient . . . . . but 10-15% surplus air is not needed for full combustion in 2014 F1 IMO

I have thought further about this and the reasons that 10-15% surplus air has always produced best BTE. I had always thought (perhaps like yourself) that it was all about mixing and that a stoichiometric mixture would produce best BTE if 100% mixed.

1. Even if that was the case, it is very unlikely that a DI system could achieve 100% mixing, in cylinder, at 10,500 rpm.

2. On reflection, a stoichiometric mixture would never achieve best BTE. Significant excess air is probably still needed to drive the combustion reactions predominantly in the direction of CO2 and H2O - early in the power stroke. During the combustion phase reactions are constantly occuring in both directions and excess O2 helps to favour those headed in the forward direction (the exothermic ones) again - early in the power stroke - heat produced later is less efficiently converted to work.

3. Likewise during combustion, some of the O2 is tied up in NOx production (more in fact than tailpipe emissions would suggest since some of these NOx species may dissociate later in the power stroke as the combustion products cool). Excess air is needed to make up the shortfall.

[ringo]

I'm not doubting gruntguru, but I wont buy it till it's demonstrated. I'm still of the opinion that the total efficiency is with the ERS.

I think grunt is also including the ERS - but not the ES - in the efficiency equation.

That is, peak efficiency is when the ICE is operating with the MGUH/MGUK as a turbo-compound - self sustaining mode, as described by Cosworth.

There is no additional input from the ES - whose stored energy can be from recovered braking energy, the MGUH, the MGUK (dragging the ICE under acceleration) or the power station down the road.

It is hard to put a number on the amount of power the MGUH can deliver back to the MGUK. Cosworth's graphs from some time back suggested about 100hp - 75kW.

I have calculated the self sustaining energy.. give me a few hours to find out what i had done in the past year regarding that...

[ringo]

Yes, this is what i had. This is brake thermal efficiency, meaning the mechanical efficiency plays a role (friction losses)
Now for self sustaining, you can see why renault is saying it's a bit more than 40%.
Hence why i'm doubtful about the ICE by itself being 40%.
If i ignore mechanical friction losses, the efficiency would be commendable 36% at some point. but in reality it's about 32% if i say the losses are roughly 15%.

Anyhow heres the graph, could be wrong and could be right:


you will find most of my graphs having that bump. This is realy just the poor transisition from the fuel flow equation stipulated by the FIA.

This was done by looking at the available heat energy from the turbine after the compressor has taken it's share. It however ignores electrical conversion inefficiencies.

[chip engineer]

Yes, this is what i had. This is brake thermal efficiency, meaning the mechanical efficiency plays a role (friction losses)
Now for self sustaining, you can see why renault is saying it's a bit more than 40%.
Hence why i'm doubtful about the ICE by itself being 40%.
If i ignore mechanical friction losses, the efficiency would be commendable 36% at some point. but in reality it's about 32% if i say the losses are roughly 15%.

Anyhow heres the graph, could be wrong and could be right:
http://s1010.photobucket.com/user/ducka ... 5.png.html

you will find most of my graphs having that bump. This is realy just the poor transisition from the fuel flow equation stipulated by the FIA.

This was done by looking at the available heat energy from the turbine after the compressor has taken it's share. It however ignores electrical conversion inefficiencies.

I think your self-sustaining numbers agree reasonably well with the Cosworth simulations.
But your ICE is much lower and MGU-H much higher than Cosworth reported (about 20% additional power from the MGU-H at 12000 rpm: 605hp ICE, 725 self-sustaining).
It looks like you have about 40% additional power from the MGU-H.

[ringo]

It's difficult to determine how much available energy can be harvested without any turbine characteristics.
But who knows, maybe Mercedes data has even more MGUH power than Cosworth.

grunt Guro has to show something to support 40% ICE alone. If that were the case, we'd have this technology on the streets as we speak. That's some amazing numbers from an engine alone, muchless a race engine that revs as high as sport street engine.

[gruntguru]

I think 40+% claimed by MB is ICE (crankshaft) + turbine excess power (MGUH). I agree with chip engineer, the turbine recovery portion of your simulation is too high and the crankshaft brake efficiency too low. Without doing the maths, the turbine portion you show may even be greater than 120kW. That would be significant because only 120kW can be sent to the MGUK for immediate use - the remainder going to the ES and unable to be added to the brake power of the PU.

[Tommy Cookers]

past experience means nothing here. with DI at 500 bar we do not need 10-15% surplus air for complete combustion of the fast-combusting race fuel maybe 2% surplus air is sufficient . . . . . but 10-15% surplus air is not needed for full combustion in 2014 F1 IMO

I have thought further about this and the reasons that 10-15% surplus air has always produced best BTE. I had always thought (perhaps like yourself) that it was all about mixing and that a stoichiometric mixture would produce best BTE if 100% mixed.
1. Even if that was the case, it is very unlikely that a DI system could achieve 100% mixing, in cylinder, at 10,500 rpm.
2. On reflection, a stoichiometric mixture would never achieve best BTE. Significant excess air is probably still needed to drive the combustion reactions predominantly in the direction of CO2 and H2O - early in the power stroke. During the combustion phase reactions are constantly occuring in both directions and excess O2 helps to favour those headed in the forward direction (the exothermic ones) again - early in the power stroke - heat produced later is less efficiently converted to work.
3. Likewise during combustion, some of the O2 is tied up in NOx production (more in fact than tailpipe emissions would suggest since some of these NOx species may dissociate later in the power stroke as the combustion products cool). Excess air is needed to make up the shortfall.

IIRC if you are now defending 10-15% lean rather than 30% lean, agreed that's easier

regarding your claim for the benefits to BTE of (10-15%) lean ......
textbooks present fuel:air cycle predicted benefits as rather optimistic compared to benefits measured in actual test engines
(in plots apparently derived from work in the 1960s by Edson or Edson & Taylor on old, carburetor-fueled engines)
these plots (eg in recent Ganesan and 60s Taylor books) present such benefits as measured to TE (not BTE)
with leaning the power at the piston falls but the friction does not ie there is little or less benefit to BTE
and restoring power while remaining lean requires a 'larger' engine ie increased massflow giving further disbenefit to BTE

having posted several times mentioning dissociation without any response .......
I cannot agree with your view that lean mixture is helpful in this regard, 80 years experience has shown otherwise
rising CO levels with stoichiometric (or richer) mixture strongly deter dissociation of CO2 back to CO eg according to Ganesan
aviation texts concur, also furnace design seems to agree and does not claim surplus air as you suggest to help over dissociation
Taylor discounts Nox as trivial and Ganesan ignores it
dissociation is primarily driven by a temperature threshold
though I speculated that fuel/additive etc chemistry can help , and suggested there is anyway a tradeoff of dissociation and HUCR
the Wright Turbo-Compound showed substantial dissociation at the port (even to CH4) in lean mixture cruise (F:A .057)
so presumably burning near the turbine
tbf even more dissociation at takeoff power, presumably due to the very high temperatures at the very high boost

[godlameroso]

I wonder if any team has used their computer simulation models to come up with a throttle map that varies from corner to corner to give the most effective braking and acceleration for each given corner. It's not impossible to do as all the cars are fitted with gps. Perhaps have a more aggressive anti-lag map at certain slow corners, in others delaying maximum power so the driver can maintain full throttle, and deploying later during the straight. I imagine adapting this with input of the drivers could potentially be worth a decent amount of lap time if the symbiosis was well executed.

[Wayne DR]

but 10-15% surplus air is not needed for full combustion in 2014 F1
IMO

The surplus air is needed, not for full combustion, but to increase the amount of energy recovered from the MGU-H. In a fuel limited system, a lower AFR is needed to run higher airflows, which in turn allows higher boost pressures, giving a larger delta P, which increases MGU-H output.

With partial stratification, the extra air will also provide thermal insulation to the cylinder walls, increasing the ICE's thermal efficiency, increasing the temperature of the exhaust gases, further increasing MGU-H output.

[gruntguru]

past experience means nothing here. with DI at 500 bar we do not need 10-15% surplus air for complete combustion of the fast-combusting race fuel maybe 2% surplus air is sufficient . . . . . but 10-15% surplus air is not needed for full combustion in 2014 F1 IMO

I have thought further about this and the reasons that 10-15% surplus air has always produced best BTE. I had always thought (perhaps like yourself) that it was all about mixing and that a stoichiometric mixture would produce best BTE if 100% mixed.
1. Even if that was the case, it is very unlikely that a DI system could achieve 100% mixing, in cylinder, at 10,500 rpm.
2. On reflection, a stoichiometric mixture would never achieve best BTE. Significant excess air is probably still needed to drive the combustion reactions predominantly in the direction of CO2 and H2O - early in the power stroke. During the combustion phase reactions are constantly occuring in both directions and excess O2 helps to favour those headed in the forward direction (the exothermic ones) again - early in the power stroke - heat produced later is less efficiently converted to work.
3. Likewise during combustion, some of the O2 is tied up in NOx production (more in fact than tailpipe emissions would suggest since some of these NOx species may dissociate later in the power stroke as the combustion products cool). Excess air is needed to make up the shortfall.

IIRC if you are now defending 10-15% lean rather than 30% lean, agreed that's easier

True - but I was responding to your claim "but 10-15% surplus air is not needed for full combustion in 2014 F1"

regarding your claim for the benefits to BTE of (10-15%) lean ......
textbooks present fuel:air cycle predicted benefits as rather optimistic compared to benefits measured in actual test engines
(in plots apparently derived from work in the 1960s by Edson or Edson & Taylor on old, carburetor-fueled engines)
these plots (eg in recent Ganesan and 60s Taylor books) present such benefits as measured to TE (not BTE)
with leaning the power at the piston falls but the friction does not ie there is little or less benefit to BTE
and restoring power while remaining lean requires a 'larger' engine ie increased massflow giving further disbenefit to BTE

At a given rpm, the mixture for best ITE will be the same for best BTE - the friction picture does not change enough to make any difference.

having posted several times mentioning dissociation without any response .......
I cannot agree with your view that lean mixture is helpful in this regard, 80 years experience has shown otherwise rising CO levels with stoichiometric (or richer) mixture strongly deter dissociation of CO2 back to CO eg according to Ganesan aviation texts concur, also furnace design seems to agree and does not claim surplus air as you suggest to help over dissociation Taylor discounts Nox as trivial and Ganesan ignores it dissociation is primarily driven by a temperature threshold though I speculated that fuel/additive etc chemistry can help , and suggested there is anyway a tradeoff of dissociation and HUCR the Wright Turbo-Compound showed substantial dissociation at the port (even to CH4) in lean mixture cruise (F:A .057) so presumably burning near the turbine tbf even more dissociation at takeoff power, presumably due to the very high temperatures at the very high boost

Dissociation in the exhaust system and in furnaces is a very different animal to what happens near TDC at 150+ bar. Lets simplify the picture. Basic chemistry tells us:
1. If you want to favour complete consumption of the available oxygen - add excess fuel.
2. If you want to favour complete consumption of the available fuel - add excess oxygen.

Situation "1." is the one we have been familiar with for producing max power from airflow restricted engines - both race and road. Situation "2." is what we have been familiar with for producing best fuel economy. Now situation "2." also applies for producing max power from the current fuelflow restricted engines.

Interesting to note, the Wright Turbo Compound at cruise power exhausts 4.6% of the fuel energy as unburned products despite operating with 21.5% excess air. It is unlikely that 2014 F1 engines are achieving "full combustion" with substantially less excess air than this.