Ferrari Power Unit Hardware & Software

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
bergie88
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hemichromis wrote:I have heard of this technology before. It was expected to improve fuel consumption by 'up to 50%' in road cars.
I'd be surprised if Ferrari took the risk of a very new way of doing it - and the potential reliability problems - when they are so close to Mercedes in terms of power
I think you are talking about HCCI, a very promising technology combining the advantages of gasoline and diesel engines. More information about it can be found on wikipedia for instance.

300 bar is certainly not bmep, but since the M in bmep stands for mean, it might be peak pressure during the combustion cycle.

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pgfpro
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gruntguru wrote:300 bar peak-cylinder-pressure is certainly pushing the boundary. I have never heard of such a high pressure in an SI engine. Even diesels don't normally go that high.
I have heard that some of the big $$$ nitrous engines make around 300bar combustion pressure, but most only live around 6 seconds or less ;)
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dmjunqueira
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gruntguru wrote:300 bar peak-cylinder-pressure is certainly pushing the boundary. I have never heard of such a high pressure in an SI engine. Even diesels don't normally go that high.
Old mechanic injection diesels maybe don't...Modern common rail diesels reach injection pressures in excess of 2000 bar!
See for yourself:
http://de.bosch-automotive.com/pt_BR/pa ... rsys_parts

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FW17
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dmjunqueira wrote:
gruntguru wrote:300 bar peak-cylinder-pressure is certainly pushing the boundary. I have never heard of such a high pressure in an SI engine. Even diesels don't normally go that high.
Old mechanic injection diesels maybe don't...Modern common rail diesels reach injection pressures in excess of 2000 bar!
See for yourself:
http://de.bosch-automotive.com/pt_BR/pa ... rsys_parts
It is not the injector fuel delivery pressure that they are talking of, it is the peak pressure of the gasses in the combustion chamber.

For a comparison Mahle who makes pistons for the audi TDI lemans engines mentions the peak pressure as far more than 200 bar (so I assume it was not more than 250 bar), so the current 220 bar that is stated itself may be quiet high.

Brian Coat
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pgfpro wrote:
gruntguru wrote:300 bar peak-cylinder-pressure is certainly pushing the boundary. I have never heard of such a high pressure in an SI engine. Even diesels don't normally go that high.
I have heard that some of the big $$$ nitrous engines make around 300bar combustion pressure, but most only live around 6 seconds or less ;)
I think a nitrous engine lasts more than one run!

If we are talking ALL SI engines, including mad ones, I believe using CH3NO2 fuel can get you very much higher than that.

In the gasoline-fuelled arena there are other engines in/approaching this 300 Bar region.

I guess we'd expect overall pressure ratio (CR+boost) to be the big driver?

jure
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Can someone knowledgeable estimate how much power this could bring? Maybe piston speed times max pressure? But in this case, this would be huge increase, so it doesn't work like that. So let's assume peak pressure increases by 20% and average pressure increases just by 10% - is it too much? Then power should also increase by 10% which is about 60hp.
It was said that Mercedes Monza upgrade should deliver up to 30-40 more hp (when they unleash all potential), although this is a large number and is quite hard to believe. If all numbers are correct Ferrari and Mercedes should both have about same power from their new ice.

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ringo
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For my engine calculations i see about 255 bar combustion pressure.
300 is not particularly outrageous. If the A:F is leaned out a bit and the boost and compression ratio are increased 300 is very much attainable. The trick is controlling the ignition of the fuel mix, but i guess this is easier with direct injection.
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godlameroso
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I guess if you've reached what's possible through combusting gasoline, you can get that extra little umph on the combustion stroke by maximizing cylinder pressure. Another unintended consequence of having a completely unlimited MGU-H, honestly the fact that it's such a black box means that it's power is really the biggest differentiator. Not only does it create free electric energy to drive the wheels, but it also increases power to the combustion engine through the compressor. The biggest engineering challenge is to make a very powerful MGU-H that is very efficient as a generator without causing a lot of back pressure, maybe by increasing the cylinder pressure the exhaust pulses have more energy, indirectly creating more power by more generator action from the MGU-H.
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Per
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jure wrote:Can someone knowledgeable estimate how much power this could bring? Maybe piston speed times max pressure? But in this case, this would be huge increase, so it doesn't work like that. So let's assume peak pressure increases by 20% and average pressure increases just by 10% - is it too much? Then power should also increase by 10% which is about 60hp.
It doesn't work like that. The higher pressure also has to be generated, i.e. more work has to go in during the compression stroke (and/or the compressor has to deliver a higher pressure, at the expense of higher back pressure from the turbo).

More work in, more work out, no net power increase in the way you describe. BUT, at higher pressure the thermal efficiency goes up, as pointed out by Tommy Cookers on the previous page. So there is an increase in power, but you cannot say "10% higher pressure means 10% more power".

gruntguru
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bergie88 wrote:
hemichromis wrote:I have heard of this technology before. It was expected to improve fuel consumption by 'up to 50%' in road cars.
I'd be surprised if Ferrari took the risk of a very new way of doing it - and the potential reliability problems - when they are so close to Mercedes in terms of power
I think you are talking about HCCI, a very promising technology combining the advantages of gasoline and diesel engines.
According to the article, when running these pressures, ignition occurs prior to the spark which is indeed a situation similar to HCCI. The H in HCCI stands for homogeneous ie well-mixed charge with constant AFR throughout. We can be sure that this is not the case in the current F1 engine which almost certainly has a stratified charge - lean at the boundaries. It is possible however, that the richer parcel of mix in the centre of the chamber is igniting simultaneously at many sites - same as HCCI.

There is no consistent relationship between Peak Cylinder Pressure (PCP) and BMEP or efficiency. In the Ferrari case, the increase in PCP is gained mostly by faster combustion. If you look at the diagram below you can see that the area inside the red loop is hardly any larger than the blue loop. BMEP, torque and power are essentially proportional to this area so it is obvious that PCP can be increased significantly with little effect on power.

Image

A word on detonation. Detonation is much more than just very rapid combustion. Normal combustion sees a flame front (roughly spherical) starting at the spark plug and moving outwards. The propagation of this flame front relies on heating the unburned molecules just ahead of the flame to their "ignition temperature". This is similar to what happens when a trail of fuel poured onto the ground is lit at one end. In the hot, turbulent combustion chamber, a normal flame front travels quite fast but it needs to, to get the charge burned and the cylinder pressure up, before the piston travels too far down the bore.

During knocking combustion or "detonation", the unburned charge ahead of the flame front, is so hot and compressed that a small pressure shock is sufficient to ignite it. Under these conditions the flame will travel as fast as the pressure wave from preceding combustion can move across the chamber. The flame front is now travelling at the speed of sound and the pressure wave travelling with it is amplified by the combustion occurring within it. If a large fraction of the charge is burned at this speed, the pressure wave will be very steep and tall by the time it gets to the chamber wall. When it hits, it has the force (and sound) of a hammer blow, creating the distinctive "rattle" or "ping".
Last edited by gruntguru on Sat Jan 23, 2016 4:20 am, edited 1 time in total.
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Per
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Great stuff, thanks for sharing. In my previous post, I didn't even think of faster combustion leading to higher peak pressure. #-o I have a lot to learn. But as you point out and as the plot shows, if the higher pressure comes purely from faster combustion, the effect is short-lived and the total power benefit is marginal. Marginal benefits are important, but I doubt that this is the step change that the Motorsport.com article makes of it.

Tommy Cookers
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given that F1 can't DiesOtto itself because it can't directly vary the CR or achieve an equivalent effect by using VVT .....

HCCI is obtainable by modulating the turbine load to underscavenge substantially, the raised charge temperature triggering CI

this has been done in 2 strokes in public demonstration eg Honda by controlling the exhaust port to restrict scavenge
it seems such CI is stable and reliable

(I asked years ago about controlled underscavenge, some seem adamant that positive scavenge is vital to the exhaust valves)

Per
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Would it be feasible to modulate intake air temperature by modulating intercooler behaviour? For example by having two independent intercooler circuits (air-air and water-air, or simply a large one and a small one) and carefully mixing air from both circuits by means of a pressure regulating valve. If well implemented, this would give you active control of plenum air temperature and therefore more control of in-cilinder conditions required for auto-ignition.

It's just an idea, probably the temp control would be far too slow for this application but it might still be helpful to keep the boundary conditions more or less constant.

jure
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I'm not familiar with regulations, but would it be allowed, possible and efficient to use "5-stroke" concept? Link: http://www.ilmor.co.uk/capabilities/5-stroke-engine It seems suitable for v6 engine.

gruntguru
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Per wrote:Would it be feasible to modulate intake air temperature by modulating intercooler behaviour? For example by having two independent intercooler circuits (air-air and water-air, or simply a large one and a small one) and carefully mixing air from both circuits by means of a pressure regulating valve. If well implemented, this would give you active control of plenum air temperature and therefore more control of in-cilinder conditions required for auto-ignition.
It is likely one or more teams are doing this. Honda did it on the RA168e simply by regulating a quantity of charge air to bypass the intercooler.

http://www.k20a.org/upload/HondaRA168EEngine.pdf
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