What will come after the 2.4 V8?

[PlatinumZealot]

He said multiple event is required for good stratified charge injection. This is something that gives more power and fuel economy.

[WhiteBlue]

Why restrict to 10 degrees? Or a multiple event for that matter?

I can only tell you what I have read. The book says the spray pattern of a hollow cone is essential to the combustion method. It means that the shape of the cone and the particle size must remain fairly constant to work properly. Late compression injection is necessary for the localized fuel air mix not to lean out and distribute which would occur over a longer compression period. The fuel must also be prevented to penetrate deeper than 15-20 mm in order to not hit the piston. Fuel in wall contact does not evaporate properly and results in insufficient combustion.

I believe the 2013 formula will have some sporting rule changes which will further amplify the advantages of fuel efficiency. As ESPImperium posted there will be total race fuel load restrictions in place that will mean that engines and chassis with better fuel efficiency will be able to run on higher power settings than less efficient cars. We already have this effect today with the under fueling, but I think it will be amplified by new sporting rules. With that rule not the highest power engine will win but the engine which can go to the highest power setting over the longest time. It means the highest competitive advantage come from the highest fuel efficiency. F1 Engineers will have to change their thinking.

[ringo]

I see.

[PlatinumZealot]

The German book that I quoted says that only spray guided combustion with outward opening nozzles will deliver the highest fuel savings.

It also says that all fuel injection for this method must occur between 20-10° crank shaft angle before the upper piston position in the compression phase. It says that only multiple injections allow the use of stratified charges for higher loads.

The best equipment mentioned are directly piezo operated injectors which are said to have only 30-50 micrometer of needle stroke but should theoretically have a stroke of only 7 micrometers for best performance and compact injector design.

It is also mentioned that 50-120 bar injection is typical for older combustion methods with spin nozzles and non spray guided combustion. The higher 200 bar systems are typical for outward opening piezo driven injectors and spray guided combustion.

I have figured that the 10° crank angle window for injection @ 10,000 rpm means that the time for all injection to take place is 0,00017 s. If the piezo injector can deliver 0.0002 s a multiple event is not possible and the potential for faster engine speeds is not there.

It indicates that indeed Ferrari are the leading manufacturer and that they are doing better than Porsche.

So 10/360 revolution / 10000rpm = 0.00017 seconds. I follow that.

So that is the accuracy required. nothing over 0.00017 seconds, and Aiming for 20 degrees before the piston reaches the top of the cylinder.

Good. That is not the time for the injection to take place though. That is the accuracy.

Let me use an analogy. You have a lazer gun. It takes 10 minutes to charge and fire. The laser beam takes 0.01 seconds to hit the target. The laser must hit the target between 1 and 2 seconds after firing.

If You need two laser firing events in this range it is impossible I agree. Since it takes 10 minutes to charge the gun. And the window is 1 second.
(I am interested in the "10 minutes" charging time)

Now, the question is, do 2 events take place in this time? Or just one event. Maybe the second event is before or after this window?

Wikipedia again

It is also possible to inject more than once during a single cycle. After the first fuel charge has been ignited, it is possible to add fuel as the piston descends. The benefits are more power and economy, but certain octane fuels have been seen to cause exhaust valve erosion. For this reason, most companies have ceased to use the Fuel Stratified Injection (FSI) operation during normal running.

So this is the killer. It seems that the second shot is after initial combustion.
So the time for the injector to "charge up" to fire the second shot is extended.

The time between the first and second shot Is what is the next part of the problem. The Injector must be able to repeat fire faster than this time.

So some unknown degrees after TDC minus 20 Degrees before TDC is the maximum required time that the injector should not pass to fire a second time. This is the time is the key factor to see if stratified charge can be used in F1.

[WhiteBlue]

From what I understand the piezo injector is capable of making a full opening stroke, remain open for enough time and close again in 0.0002 s. These injectors also deliver the highest flow rates with the finest particle size. There is no charging time at all. The injector can theoretically do a second event directly behind the first. The ignition is actually some degree after TDC and the 12-15° ignition after injection is required to evaporate the fuel and help it cool the compressed air.

I would love to read more about modern high efficiency combustion. So if anyone here comes across a good book or article please share.

[ringo]

This 10 to 20 degree event, this is for ultra lean burning correct?

But for normal and high load conditions, injection may begin sometime earlier, on the intake stroke maybe, to maximize the amount of fuel you can get in the cylinder in a limited time. Normal and high load running have more time afforded for injection that for lean running.
Especially for turbocharged performance engines, with high air content and maximum amount of fuel is required, we may only see the late injection occurring when the driver needs to save fuel.

[WhiteBlue]

This 10 to 20 degree event, this is for ultra lean burning correct?

But for normal and high load conditions, injection may begin sometime earlier, on the intake stroke maybe, to maximize the amount of fuel you can get in the cylinder in a limited time. Normal and high load running have more time afforded for injection that for lean running.
Especially for turbocharged performance engines, with high air content and maximum amount of fuel is required, we may only see the late injection occurring when the driver needs to save fuel.

Spray guided combustion is relying on the 20-10° window. It achieves 15-20% better fuel efficiency compared to port based injection. Apparently you can run wall based and air based combustion and incur considerable efficiency penalties. In the extreme case of wall based combustion the improvement against port based injection can be just 5%. So wall based is really the worst. It injects the fuel on the piston and injects at an 80-65° window in the compression stroke.

Air based relies on creating revolving flows in the compressing air charges which leads to pumping losses. It works in a 55-40° window. Improvements are said to be up to 15% compared to port based if I understand it right. But the improvements can be substantially smaller when aerodynamic losses occur due to the shape of the particular piston geometry that creates the movement in the compressing air. The figure are a bit vague. For a rough estimate I would put if like:

wall based -> -(5 to 10%) fuel use compared to port based
air based -> -(8 to 15%) fuel use compared to port based
spray based -> -(15-20%) fuel use compared to port based

Finally there is some info on injection mass flow. Outward opening piezo driven nozzles achieve 30 g/s injection flow while the older models do only 10 g/s. All based on the book from 2007.

[tok-tokkie]

I have limited time so have not been able to read the last 2 pages.

I am aware of piezo direct injection on Evenrude 2-stroke outboard engines. I believe the injector is also the pump. Here is so,ething I have found doing a quick Google:

A comparison of the basic specifications showing the new E-TEC injector with the existing DI injector, serves to highlight why this new design is so superior. The existing DI injector is capable of about 45hp per cylinder - more than we need for all current outboards, but not by very much. The existing DI injector is capable of 7500rpm, again more than we currently need, but not by much. The E-TEC injectors can beat these figures easily and inject all the fuel required in half the time. 0.0025 seconds is about one quarter of a revolution (90 degrees) at 5000remp. The E-TEC injector can also exceed 600psi ensuring very good atomisation of the fuel.

source: http://www.leisure-marine.com.au/Evinrude/article6.asp
Sorry about the quaint archaic units. 600psi is only 41 bar.

[madtown77]

Wikipedia again

It is also possible to inject more than once during a single cycle. After the first fuel charge has been ignited, it is possible to add fuel as the piston descends. The benefits are more power and economy, but certain octane fuels have been seen to cause exhaust valve erosion. For this reason, most companies have ceased to use the Fuel Stratified Injection (FSI) operation during normal running.

I would guess that burning up the exhaust valves has more to do with injecting too much too late and not fully burning in the cylinder. A higher octane fuel burns slower so they may have not compensated for that.

Spray guided is most efficient due to the ability to run at lean conditions. For spray guided I would think you will be RPM limited not only based on the injector specifications, but also on getting the spray near the spark plug with the intense amount of turbulence that occurs within the cylinder at that kind of piston speed, let alone doing it multiple times per stroke.

It indicates that indeed Ferrari are the leading manufacturer and that they are doing better than Porsche.

Well, sort of. It indicated that Ferrari are buying better components than Porsche and are being more ambitious, but in F1 you can bet everyone will be trying to get their injectors from within one or two companies and the playing field will be leveled quickly.

[tok-tokkie]

I think you guys are barking up the wrong tree when looking at the maximum revs the engine will be capable of with GDI.
1. The quantity of fuel available for the race is severely limited.
2. The maximum size of the engine is prescribed.
3. Forced induction is permitted.
4. To burn that fuel of #1 takes a specific quantity of oxygen. (I accept that that specific is only stoichiometric & that variations from that will take place but the amount of oxygen required is still more or less determined by the quantity of fuel available.)
5. The hunt for higher revs in F1 up until now with no forced induction permitted, fixed engine capacity and as much fuel as you liked was so that the engine could suck in more air so it could burn more fuel and thus release more energy.
6. The criteria for #5 no longer apply as the fuel is limited.
7. The challenge under the new rules is maximum fuel efficiency so as little of the issued energy is wasted.
8. Maximum efficiency in fact makes lower revs much more desirable as the friction forces and inertia reversal forces are reduced.

[WhiteBlue]

7. The challenge under the new rules is maximum fuel efficiency so as little of the issued energy is wasted.
8. Maximum efficiency in fact makes lower revs much more desirable as the friction forces and inertia reversal forces are reduced.

I agree that this is indeed what we are probably going to see if the reported fuel limiting policies are going to apply. It is the rational consequence.

I reckon that some fans will have a problem to accept the paradigm shift away from air limited to fuel limited formula. Lower revving engines with the turbo exhaust gas energy utilization will have a different acoustic signature to the screaming V8s we have today. So this will be a change that will be more difficult to embrace for some of us.

On the upside we will have a decent technical contest going that really is about something valuable for the public. To win races and championships teams will have to come up with new ideas to improve efficiency and that is something that will be great to watch. I much rather discuss fuel injection technology and thermodynamics than arcane aerodynamic configuration changes.

We have some of this already going in on MotoGP where engine technology is playing a bigger role and fuel is also more limited than in F1.

[ringo]

Wikipedia again

It is also possible to inject more than once during a single cycle. After the first fuel charge has been ignited, it is possible to add fuel as the piston descends. The benefits are more power and economy, but certain octane fuels have been seen to cause exhaust valve erosion. For this reason, most companies have ceased to use the Fuel Stratified Injection (FSI) operation during normal running.

I would guess that burning up the exhaust valves has more to do with injecting too much too late and not fully burning in the cylinder. A higher octane fuel burns slower so they may have not compensated for that.

Spray guided is most efficient due to the ability to run at lean conditions. For spray guided I would think you will be RPM limited not only based on the injector specifications, but also on getting the spray near the spark plug with the intense amount of turbulence that occurs within the cylinder at that kind of piston speed, let alone doing it multiple times per stroke.

The type of efficiencies we are running with for spray guided injection, is severly lean running. When i mean severe i mean this:

* Ultra lean burn mode is used for light-load running conditions, at constant or reducing road speeds, where no acceleration is required. The fuel is not injected at the intake stroke but rather at the latter stages of the compression stroke, so that the small amount of air-fuel mixture is optimally placed near the spark plug. This stratified charge is surrounded mostly by air which keeps the fuel and the flame away from the cylinder walls for lowest emissions and heat losses. The combustion takes place in a toroidal (donut-shaped) cavity on the piston's surface.The cavity is displaced to one side of the piston, the side that has the fuel injector. This technique enables the use of ultra-lean mixtures impossible with carburetors or conventional fuel injection.
* Stoichiometric mode is used for moderate load conditions. Fuel is injected during the intake stroke, creating a homogenous fuel-air mixture in the cylinder. From the stoichiometric ratio, an optimum burn results in a clean exhaust emission, further cleaned by the catalytic converter.
* Full power mode is used for rapid acceleration and heavy loads (as when climbing a hill). The air-fuel mixture is homogenous and the ratio is slightly richer than stoichiometric, which helps prevent knock (pinging). The fuel is injected during the intake stroke.

This ultra lean setting surely cannot be used for full power running. The fuel has a limited amount of energy per Kg. Not only that but lean running produces more NOx emmissions, unless a catalyst is used. F1 do not use catalyst on their exhaust.
Then there is the constant speed and no accleration bit.
What we will see is that the option will be there to run this lean, but most of the time the engines will be running in Full power mode, which is not rpm limited like the ultra lean mode.
The technology is not limited; it just that the ultra lean requirements greatly reduce the window, where maybe a sinlge injection is possible, but not multi.

Burning the exhuast valves are more related to the type of fuel used as well.
I think the ideas that we have here for efficiency is much more strict than we will actually see. We are dealing with race cars here, not production cars.

Power is power, if you want to run less revs, that proportionately affects power. You have to compensate by increased boost pressure, which takes power from the turbine anyway, and still increases friction because cylinder pressures are high, and the fuel requirement is still the same.

[WhiteBlue]

Spray guided is most efficient due to the ability to run at lean conditions. For spray guided I would think you will be RPM limited not only based on the injector specifications, but also on getting the spray near the spark plug with the intense amount of turbulence that occurs within the cylinder at that kind of piston speed, let alone doing it multiple times per stroke.

I reckon that you would be able to run at 18,000 rpm with spray guided combustion but that it would compromise your efficiency. You would simply have to start already at much bigger angles like 40° or 35° and some of your earlier injected fuel would splash against the piston and would be carried to cylinder locations where you are not wanting it. So you would be working with much lower AFRs and would be loosing much of the benefits of direct injection.

As tok-tokkie pointed out it would not be a useful strategy within the framework of the new formula to do so.

[xpensive]

I think you guys are barking up the wrong tree when looking at the maximum revs the engine will be capable of with GDI.
...
8. Maximum efficiency in fact makes lower revs much more desirable as the friction forces and inertia reversal forces are reduced.

This is very interesting, when it's close to what I work with irl, powerloss on an oilfilm, everything else equal, goes with the square of speed. Reason for that is shear-force on said film increases lineraly with speed, while power is force times speed. Pretty much like aerodynamic resistance in other words.

The other thing is that one might suspect that you would find it easier to accomplish a more complete fuel-burning sequence at lower revs, am I totally wrong there?

[ringo]

An interesting diagram here, to supplement the discussion.

What we are seeing here is extreme lean burning . I don't how much greatly reduced the power will be from the 750hp we are expecting. But from what i can see only some of the air is being combusted. Only air in that little pocket of the piston.


This creates an artificial reduction in displacement of the engine basically. Stoichometric mixing is taking place in the pocket, but when the rest of the air in the cylinder is taken into account that is when we get the extreme Air to Fuel ratios.
The lean running is interesting, but i am wondering at which stage in a race will this technique be used, and also; what amounts of reduction in power will we see as oposed to GDI injection from early intake.