2014-2020 Formula One 1.6l V6 turbo engine formula

[TinoBoost]

Max Power comes at max efficiency when Fuel Flow limited.

Running at WOT vs running at part throttle means nothing to the engine, other than specifying the air flow. Which is meaningless for this engine formula.

Max power in "normal" engines comes at stoich to rich because they are air flow limited.

In addition, since this is a turbocompounded formula, max efficiency does not depend only on the ICE, but the turbine/MGU-K as well.

And turbines power output is directly related to mass flow & pressure ratio. Most of this output however is used at the compressor.

The fact that fuel plays such an important role in these engines, shows the importance of combustion. An given the fact the engines are direct injection, i dont think it is because of knock, especially at those high RPMs. It seems more likely that it improves stratified charge.

One other interesting aspect of those engines is also passive EGR, by maintaining high-ish backpressure and minimal valve overlap. Again, this would not be a direct negative, as air flow is not the limiting factor, fuel is. It may help keep combustion temperatures in check when running lean, or make it worse if running too lean. It does slow combustion as well.

Again, WOT=Air flow limited thus go rich. F1= fuel flow limited thus go lean.

[Pierce89]

Agreed there are other benefits to GDI especially in-cylinder evaporation and its effect on charge temperature. "Very late injection" is only possible at part load and has limited relevance to F1. Hopefully technology will reach the point where this changes.

Fully stratified charge "making them smaller" will not reduce power in these F1 engines. As shown earlier in this thread these engines are capable of breathing far more air than is needed to burn the fuel allocation.

The "extra boost requirement" will increase mass flow and pressure ratio through the turbine and more than compensate for the additional compressor work required. Efficiency of a gas turbine (Brayton cycle) with a fixed fuel (heat) input increases with pressure ratio.

If the extra boost requirement was "more than compensated" then this becomes a perpetual motion machine and more boost always equals extra turbine power which can be recovered.. I don't see that as the case.

As an aside, while the Brayton is I guess partially comparable because of the mgu-h, I don't feel it makes a good comparison because of the fact that we have to get most of the power from the ICE, still.

[langwadt]

Agreed there are other benefits to GDI especially in-cylinder evaporation and its effect on charge temperature. "Very late injection" is only possible at part load and has limited relevance to F1. Hopefully technology will reach the point where this changes.

Fully stratified charge "making them smaller" will not reduce power in these F1 engines. As shown earlier in this thread these engines are capable of breathing far more air than is needed to burn the fuel allocation.

The "extra boost requirement" will increase mass flow and pressure ratio through the turbine and more than compensate for the additional compressor work required. Efficiency of a gas turbine (Brayton cycle) with a fixed fuel (heat) input increases with pressure ratio.

If the extra boost requirement was "more than compensated" then this becomes a perpetual motion machine and more boost always equals extra turbine power which can be recovered.. I don't see that as the case.

as you get nearer the theoretical limit the gains would be smaller and smaller, and eventually the max. temperature of materials, compressor efficiency etc. will stop the gains

As an aside, while the Brayton is I guess partially comparable because of the mgu-h, I don't feel it makes a good comparison because of the fact that we have to get most of the power from the ICE, still.

agreed, if it was really just Brayton cycle, you would want maximum boost and no intercooling, maybe even heating

[gruntguru]

Did you really write that last question? Do you not understand the compression/temperature benefits of high pressure GDI with a very late injection? Surely, if you're talking stratified charges you should already understand these benefits.

Besides, you don't have to have "significant" stratification to run slightly richer around the plug tip. The "fully stratified" systems with no fuel at all close to the cylinder walls effectively reduce your volumetric efficiency in exchange for the increase in thermal efficiency. In other words, you've got a smaller less powerful but very efficient engine. That's why its not done in WOT situations. It reduces overall power and the extra boost requirement would reduce rcoverable power at the turbine too.

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.

[gruntguru]

Agreed there are other benefits to GDI especially in-cylinder evaporation and its effect on charge temperature. "Very late injection" is only possible at part load and has limited relevance to F1. Hopefully technology will reach the point where this changes.

Fully stratified charge "making them smaller" will not reduce power in these F1 engines. As shown earlier in this thread these engines are capable of breathing far more air than is needed to burn the fuel allocation.

The "extra boost requirement" will increase mass flow and pressure ratio through the turbine and more than compensate for the additional compressor work required. Efficiency of a gas turbine (Brayton cycle) with a fixed fuel (heat) input increases with pressure ratio.

If the extra boost requirement was "more than compensated" then this becomes a perpetual motion machine and more boost always equals extra turbine power which can be recovered.. I don't see that as the case.

As an aside, while the Brayton is I guess partially comparable because of the mgu-h, I don't feel it makes a good comparison because of the fact that we have to get most of the power from the ICE, still.

Correct, the Brayton does not make a good comparison. I only raised it to counter statements like your first sentence. Brayton cycle efficiency increases with PR but converges to a limit - so not perpetual motion.

[Wayne DR]

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

Thanks for the explanation, I think I finally get it now. I had always considered the "fresh air" surrounding the air-fuel mixture in a Stratified charge as a potential energy loss, soaking up heat. I had never considered the thermal insulation properties, and that it will actually soak up less heat/energy than the cylinder wall, increasing efficiency.

The real challenge (in my mind anyway) is to stop separating the ICE from the compressor, turbine and MGU-H/K. As the rules don't limit the direct energy transfer between the MGU-H and MGU-K, these power units are not simply turbocharged internal combustion engines, but complex "combined" thermodynamic engines.

I am interested in the technology, and have been searching the internet for research papers on this, but everything I have found so far is written for airflow restricted scenarios (I don't believe Ferrari, Renault or Mercedes will be publishing anything soon...)

[gruntguru]

I had always considered the "fresh air" surrounding the air-fuel mixture in a Stratified charge as a potential energy loss, soaking up heat. I had never considered the thermal insulation properties, and that it will actually soak up less heat/energy than the cylinder wall, increasing efficiency.

In fact the sole purpose of combustion is to heat-up and raise the pressure of the working fluid (air) so heating pure air is just as useful as heating a mix of air, fuel and combustion products.

[Brian Coat]

(Very) Lean at 10,000 rpm at WOT ... I've been thinking about it ... Or trying to ...

Do we all agree that the homogeneous charge version of this high airflow concept would not work?

Re stratified: I think it may be very tricky to obtain usable stratified charge combustion at 10,000 WOT.

I could be wrong ... With the right injection strategy (Multiple late injections?) and you might get the stratification BUT charge preparation, combustion timing and duration also have to be right. And this is no Diesel - this all has to work efficiently at 10,000 rpm. And you are only allowed 500 Bar fuel pressure?

How would you achieve this?

[Brian Coat]

Leaving aside all this fancy ultra-lean stuff for a sec ...

... it's clear that increasing the pressure ratio of a heat engine is going increase efficiency, but for an SI engine there will be a knock limit involved whether your are increasing boost, CR or both.

... and pretty soon you'll be on the phone to your friendly fuel supplier to brew up something which meets the spec but extends knock limit.

See other thread ...

[ringo]

This discussion about direct injection is futile until we get information from the engine makers about what they are doing with it.

[gruntguru]

(Very) Lean at 10,000 rpm at WOT ... I've been thinking about it ... Or trying to ...
Do we all agree that the homogeneous charge version of this high airflow concept would not work?

I think that 1.1 - 1.15 is the right mixture for the homogeneous version of a restricted fuel flow formula. Leaner numbers would require stratification.

Re stratified: I think it may be very tricky to obtain usable stratified charge combustion at 10,000 WOT.

I could be wrong ... With the right injection strategy (Multiple late injections?) and you might get the stratification BUT charge preparation, combustion timing and duration also have to be right. And this is no Diesel - this all has to work efficiently at 10,000 rpm. And you are only allowed 500 Bar fuel pressure?

How would you achieve this?

I agree totally and this is where F1 is probably pushing the boundaries of DI technology.
Not sure if multiple injections would be needed but you probably only have 180 degrees of crank rotation or less to inject the fuel charge if you want it to stay in the right place. That amounts to a duty cycle of 25% or less for the injectors at max power. That requires a pretty hefty injector flow capacity which makes precise metering at lower outputs quite tricky. Perhaps they are able to reduce the fuel pressure at lower outputs? 1/4 pressure (125bar) for example would halve the fuel flow.

[gruntguru]

Leaving aside all this fancy ultra-lean stuff for a sec ...

... it's clear that increasing the pressure ratio of a heat engine is going increase efficiency, but for an SI engine there will be a knock limit involved whether your are increasing boost, CR or both.

For one thing, trading boost for CR will not upset the efficiency as much as a non-compound turbo engine.

The other advantage is DI and stratification. The extra air just outside the end gas will be absorbing a lot of the heat - cooler end gas = reduced detonation.

[gruntguru]

This discussion about direct injection is futile until we get information from the engine makers about what they are doing with it.

Yeah lets just shut down the forum and wait for Honda to publish in 5 - 10 years.

[alemos24]

So , in the end how much HP have these cars ?

Someone says that the ice could produces 690 Hp + 160 Ers .

[Cold Fussion]

So , in the end how much HP have these cars ?

Someone says that the ice could produces 690 Hp + 160 Ers .

Close to 600 Hp.