2014 Engine yin yang

[Holm86]

[...]And again it doesnt matter if it is fuel or air restricted. Its a ratio between the two. So it would be the same.

It is a ratio, but it does matter.

I'll try to explain with another example what motobaleno tried to explain.

Again, it is an example!

At Lambda = 0.85 = 255 g/kWh (=max. power)
At Lambda = 1.0 = 240 g/kWh
At Lambda = 1.15 = 230 g /kWh (=minimum spec. consumption)

Lambda is, in this case, not regulated with the amount of injected fuel, but with amout of air charged (which means that you have to rise boost pressure, and thus for leaner operation, consumption might not go down as much as in an air restricted engine, due to higher pumping losses).

OK, lets calculate the power the engine theoretically is able to produce if not air restricted:

Rich: 100 kg/h / 0.255 kg/kWh = 392 kW = 533 HP
Stochiometric: 100 kg/h / 0.240 kg/kWh = 417 kW = 567 HP
Lean: 100 kg/h / 0.230 kg/kWh = 435 kW = 591 HP.

Less specific consumption in a fuel restricted engine always leads to higher power output.
Whether these engines will be able running lean, I don't know.

Sorry but I do not understand this as I have no idea what you are measuring in kg/kWh?

[Holm86]

@ Holm
rich mixture's contribution to power is possible faster and more consistent combustion
neither relevant at 10500 rpm in small cylinders, with fuel ideally conditioned for combustion by v high pressure DI
or higher CR or boost using high-aromatic fuels (these won't be used in 2014 as their specific energy is much inferior)

How can a rich mixture in any cases achieve more power if it werent able to burn all the fuel?

in addition to the reasons already given as above
in 99.99999999% of cases the engine is air limited eg in current F1 by having 2400cc @ 18000 rpm
a rich mixture means more fuel than can all be burnt by that limited air
this surplus fuel means that notionally all the air will be used
because all the air ie more air is being used the heat liberated with a rich mixture will be more than with eg a stoichiometric one
with eg a stoichiometric mixture not quite all the air will be used (and not quite all the fuel)
so rich mixture will here give better power (but much worse bsfc, because some fuel is simply being thrown away unused)

current F1 certainly has more consistent combustion enabled by rich mixture use
so uses more/all of its fixed air supply when run rich, so has greater maximum power
the price is disproportionate fuel consumption
but they run some or much of every race in rich mixture

I just don't get why at stoichiometric conditions a air restricted engine wont use all the air. But a fuel restricted engine will use all the air at stoichiometric conditions. This seems contradictory and doesn't make sense to me.

[Tommy Cookers]

that wouldn't make sense to me either

[Holm86]

But that is What you Are saying?

[Abarth]

Kg or g per kWh is the measure of specific consumption of an engine.

[Holm86]

Kg or g per kWh is the measure of specific consumption of an engine.

But where are you getting these numbers from??

At Lambda = 0.85 = 255 g/kWh (=max. power)
At Lambda = 1.0 = 240 g/kWh
At Lambda = 1.15 = 230 g /kWh (=minimum spec. consumption)

[langwadt]

Kg or g per kWh is the measure of specific consumption of an engine.

But where are you getting these numbers from??

At Lambda = 0.85 = 255 g/kWh (=max. power)
At Lambda = 1.0 = 240 g/kWh
At Lambda = 1.15 = 230 g /kWh (=minimum spec. consumption)

even with out number is some how intuitively makes sense that,
hitting exactly stoic everywhere in almost impossible, so:

air limited: add a bit of extra fuel to make sure all available air is used, some fuel is wasted
fuel limited: add a bit of extra air to make sure all the fuel is burned, if hot enough and enough air even metal will burn

[Abarth]

Kg or g per kWh is the measure of specific consumption of an engine.

But where are you getting these numbers from??

At Lambda = 0.85 = 255 g/kWh (=max. power)
At Lambda = 1.0 = 240 g/kWh
At Lambda = 1.15 = 230 g /kWh (=minimum spec. consumption)

As I wrote, it is an example, no exact numbers.

They are qualitatively OK, quantitatively they may not. Although, if we look at what has been discussed about the max. power of the ICE, the specific consumption numbers are not that far from reality, maybe a bit high as we do not talk about regular fuel...

[Abarth]

Here some more bits, already in this forum:
http://www.f1technical.net/forum/viewto ... 86#p345886

[Holm86]

Okay. But if they are going to run these engines lean then they need some serious thermal barrier coatings everywhere inside combustionchamber/cylinder. Because it will get very hot running lean in such an engine at WOT.

[Tommy Cookers]

lean will be cooler than stoichiometric
(though if combustion is slowed by leaness this can raise exhaust temperature via poor expansion of charge eg valve damage)
I am advocating very near stoichiometric
88 Honda used 1.02 rich for best bench bsfc but (their SAE paper says) had to go 1.08 rich in races for response/injection reasons

[Holm86]

lean will be cooler than stoichiometric
(though if combustion is slowed by leaness this can raise exhaust temperature via poor expansion of charge eg valve damage)
I am advocating very near stoichiometric
88 Honda used 1.02 rich for best bench bsfc but (their SAE paper says) had to go 1.08 rich in races for response/injection reasons

I have allways been under the impression that leaner ment hotter. Guess I've just misunderstood something.

And I also believe the engines will run close to stoichiometric. But slightly rich of that. Something like 14-14.5:1. That is what I ment when i said rich. Im not talking about 12:1 or something like that.

[skoop]

according to AMuS the fuel sensors seem to match the requirements:

Sensoren endlich exakt genug

Aufatmen bei der FIA. Gill Sensors hat neue Durchflussmengen-Messgeräte geliefert. Ein erster Test ergab, dass die Messungen jetzt innerhalb der geforderten Genauigkeit liegen. Betrug ist also ausgeschlossen. 2014 dürfen pro Stunde nur 100 Kilogramm Kraftstoff eingespritzt werden.


in english:

according to FIA a test showed that the gill sensors finally meet all the requirements. that's why cheating will be impossible.

ps: i know that the magazines sometimes write nonsense, but since this is a yin yang thread i just post 'em so we have something to discuss

[xpensive]

And what were said requirements xactly?

[hollus]

"Genauigkeit". That's what translates into English as "exactitude" (with an e at the beginning, sorry!). No word on precision nor on the measuring conditions where the exactitude was achieved.
The part about cheating being Ausgeschlossen makes me think of someone being very, very worried exactly with the cheating part, and it also makes me think of "The princess bride". Inconceivable! (liberal translation)