What will come after the 2.4 V8?

[WhiteBlue]

Well obviously, if you by a leaner mix mean that you keep the amount of fuel injected constant, but somehow increase the amount of air, the total massflow will be higher. But I'm not sure this is how an engine works, the other way around seems somewhat more practical, if you for whatever reason want to play with this.

I'm obviously aware what Wikipedia said about useful lambdas in engines because I introduced the reference to the wiki page. I did this to show that indeed the stoichiometric AFR is 14.7.

I also added the caveat that the lambda values used in Edi's calculation are not realistic for F1 purposes. Nevertheless the principle holds true that the mass flow increases at constant fuel consumption and higher lambda values. There is no way around that basic truth. The way lambda increases in an F1 engine is by calling up fuel injection maps with shorter injection times. So to compensate for the reduction of fuel flow the driver will need to increase the throttle setting to get back on the same fuel flow at higher lambda.

If you want to compare mass flow at constant throttle and higher lambda obviously the mass flow will go down. This is why people find it difficult to understand the concept.

[xpensive]

Well obviously, if you by a leaner mix mean that you keep the amount of fuel injected constant, but somehow increase the amount of air, the total massflow will be higher. But I'm not sure this is how an engine works, the other way around seems somewhat more practical, if you for whatever reason want to play with this.

I'm obviously aware what Wikipedia said about useful lambdas in engines because I introduced the reference to the wiki page. I did this to show that indeed the stoichiometric AFR is 14.7.

I also added the caveat that the lambda values used in Edi's calculation are not realistic for F1 purposes. Nevertheless the principle holds true that the mass flow increases at constant fuel consumption and higher lambda values. There is no way around that basic truth.

It is also clear that you will hit the same fuel flow at a higher throttle setting. So if you want to compare mass flow at constant throttle and higher lambda obviously the mass flow will go down. This is why people find it difficult to understand the concept.

Finally, it seems we are in agreement.

[WhiteBlue]

Well obviously, if you by a leaner mix mean that you keep the amount of fuel injected constant, but somehow increase the amount of air, the total massflow will be higher. But I'm not sure this is how an engine works, the other way around seems somewhat more practical, if you for whatever reason want to play with this.

I'm obviously aware what Wikipedia said about useful lambdas in engines because I introduced the reference to the wiki page. I did this to show that indeed the stoichiometric AFR is 14.7.

I also added the caveat that the lambda values used in Edi's calculation are not realistic for F1 purposes. Nevertheless the principle holds true that the mass flow increases at constant fuel consumption and higher lambda values. There is no way around that basic truth. The way lambda increases in an F1 engine is by calling up fuel injection maps with shorter injection times. So to compensate for the reduction of fuel flow the driver will need to increase the throttle setting to get back on the same fuel flow at higher lambda.

If you want to compare mass flow at constant throttle and higher lambda obviously the mass flow will go down. This is why people find it difficult to understand the concept.

Finally, it seems we are in agreement.

It is a matter of selecting the right boundary conditions. You obviously have to say if you compare constant fuel flow or constant throttle setting. For your original statement constant fuel flow seems the right boundary condition, because you postulated a direct relation between fuel use and mass flow.

The issue is further compounded if you differentiate between fuel burning and fuel use. If you speak about the amount of fuel that is actually burned the ratio is constant. But fuel burned and fuel used isn't the same. In my opinion one should look at how much fuel is actually used in the engine because that is the realistic figure that you can directly measure.

[xpensive]

In my original statement that the exhaust flow being proportional to the amount of fuel burnt, I was obviously thinking a constant Lambda 1.0, a stoichiometric mixture, which is next to ideal for the IC-engine as I can understand it.

[WhiteBlue]

In my original statement that the exhaust flow being proportional to the amount of fuel burnt, I was obviously thinking Lambda 1.0, a stoichiometric mixture, which is next to ideal for the IC-engine as I can understand it.

In that case your statement is correct but not really reflecting the way the teams can run their engines. It appears they typically run the engine at much lower lambdas than 1 and they increase this value close to under 1 when they are in extreme fuel saving mode. And those changes will significantly impact the fuel use although the fuel burn rate isn't affected that much.

So we would have to ask ourselves what is the objective of the statement? To discuss something at a theoretical state or at realistic race conditions?

I would think that teams run the engine in the lowest feasible lambda condition (richest setting) for Q3 to get the highest power they can get. And that is as far away from lambda=1 as you get in an F1 engine.

[xpensive]

When discussing things in a theoretical fashion, it is common to begin with what you know as being next to ideal, not what you suspect or guess about the reality.

And why would the teams typically run their engines at very low Lambda values, wasting fuel, it doesn't make much sense when it's not going to give them any more power? All according to your recognized Wiki reference;

Similarly, rich mixtures return poorer fuel efficiency than the stoichiometric mixture. (The mixture for the best fuel efficiency is slightly different from the stoichiometric mixture.)

But either way, you were arguing that high Lambda values were increasing mass-flow to the benefit of the blown diffuser, were you not?

[WhiteBlue]

Similarly, rich mixtures return poorer fuel efficiency than the stoichiometric mixture. (The mixture for the best fuel efficiency is slightly different from the stoichiometric mixture.)

The best power lambda is probably found on the other end of the practical scale from the highest efficiency lambda setting.

But either way, you were arguing that high Lambda values were increasing mass-flow to the benefit of the blown diffuser, were you not?

I was thinking about unconventional combustion systems without throttle, with direct stratified injection and with variable valve action. Such engine management should generally have higher lambdas than the systems that are in use now. We are told that the engine will use 25% less fuel and such efficiency improvements are not likely achievable without significant improvements in combustion efficiency. So the higher lambdas I considered would hopefully apply to a max power regime as well. I'm not so sure if that will be realistic. This is why I already agreed with machin's view that new combustion systems will not significantly improve the diffusor flow.

[xpensive]

Similarly, rich mixtures return poorer fuel efficiency than the stoichiometric mixture. (The mixture for the best fuel efficiency is slightly different from the stoichiometric mixture.)

The best power lambda is probably found on the other end of the practical scale from the highest efficiency lambda setting.

Not really, you can never draw more power from the engine than the amount of oxygen available to burn the fuel,
why a richer mix will not help you in that respect.

This is why compressors, turbos and intercoolers are employed to get more O2 molecules inte the combustion chamber.

[WhiteBlue]

Similarly, rich mixtures return poorer fuel efficiency than the stoichiometric mixture. (The mixture for the best fuel efficiency is slightly different from the stoichiometric mixture.)

The best power lambda is probably found on the other end of the practical scale from the highest efficiency lambda setting.

Not really, you can never draw more power from the engine than the amount of oxygen available to burn the fuel,
why a richer mix will not help you in that respect.

Due to the high temperatures at this mixture (close to stoichiometric), detonation of the fuel air mix shortly after maximum cylinder pressure is possible under high load (referred to as knocking or pinking). Detonation can cause serious engine damage as the uncontrolled burning of the fuel air mix can create very high pressures in the cylinder. As a consequence stoichiometric mixtures are only used under light load conditions. For acceleration and high load conditions, a richer mixture (lower air-fuel ratio) is used to produce cooler combustion products and thereby prevent detonation and overheating of the cylinder head.

Actually F1 uses ion flow sensors to sense knocking conditions. Consequently they go to higher lambdas in partial load conditions as Wikipedia suggests. The knocking sensors actually help pushing the partial load lambdas to the limit. Nevertheless under full load the suppression of spontaneous self combustion still requires lower lambdas to protect the engine. So the use of lower lambdas for high power setting is ultimately caused by the spontaneous self ignition condition of the mixture. At high power levels - which means higher peak pressure - the mixture is more prone to self ignition or knocking. This can only be suppressed by a richer mix.

The more I think about this my confidence is actually rising that modern combustion technology like stratified direct injection will also drive the lambdas up in full power conditions. The stratified charge should be a lot less prone to knocking than the mixture that the engine with indirect injection can use. So we can hope that the fuel use will also be reduced at full power.

[xpensive]

Could be that way, but it's nevertheless secondary reasons, the power itself will never come from xcess fuel added.

Water injection would of course help in the very same way, if legal, check your Wiki.

[WhiteBlue]

Could be that way, but it's nevertheless secondary reasons, the power itself will never come from xcess fuel added.

I agree with that. An F1 driver will nevertheless be royally pissed off if his engine fails due to such a "secondary" effect. So for all practical purposes we have still to consider lower lambdas for full power and higher lambdas for partial power.

[PlatinumZealot]

I'm going to jump on in here. I don't know why you guys are arguing about keeping the fuel level the same and increasing the air mass. Why would you want to do that? In reality you have to reduce the power, you have to reduce the fuel level to safe fuel. All this mathematical gymnastics is unnecessary. If you want to save gas you turn down the fuel. Simples.

The fuel ratio that gives the best power is at around 12.8. Ideally it should be 14.7 but Irreversibility in the mixture such as the actual molecules themselves bouncing around and blocking each other from making proper contact, and you have the self detonation etc you have to use more fuel to overcomes these imperfections.

You can lean out the mixture to 16 to 1 for best fuel efficiency.

As said earlier by some posters, I think direct injection is the best way to have fine control over the mixture. This is contrasting to the current cars that just shower the fuel over the throttle plate. Worse at those high 18,000 rpms I can bet that they just dump fuel in and hope most of it gets burnt properly under it's own mechanisms; I doubt there is anyway for the F1 teams to REALLY control the combustion itself. All they can vary right now is vary the amount of fuel injected and the spark timing and the throttle plate. So, Direct injection and Variable valve timing coupled with slower rpms, will enable higher level fuel management.

The question of rpms with the direct injection - I don't know what is the limiting factor. I don't even know what kind of pump (lobe pump?) is used or if the injectors are fired the same way. What is limiting the frequency at which the injectors can be fired?

Oh, one interesting note. I know that some of the direct injected road cars: BMW 335i, Audi FSi, Lexus ISF have multiple fuel injection events for each cylinder. I don't remember the number of events but more than likely 2 squirts. The Audi has a very high redline ~ 8000rpm(?), if the F1 cars can make do with 1 squirt per stroke, then they can have 8000rpm x 2 = 16000 rpm theoretical maximum rpm, with off the shelf currently available direct injection technology. That is assuming that one squirt per stroke is sufficient.

[ringo]

Well obviously, if you by a leaner mix mean that you keep the amount of fuel injected constant, but somehow increase the amount of air, the total massflow will be higher. But I'm not sure this is how an engine works, the other way around seems somewhat more practical, if you for whatever reason want to play with this.

I'm obviously aware what Wikipedia said about useful lambdas in engines because I introduced the reference to the wiki page. I did this to show that indeed the stoichiometric AFR is 14.7.

I also added the caveat that the lambda values used in Edi's calculation are not realistic for F1 purposes. Nevertheless the principle holds true that the mass flow increases at constant fuel consumption and higher lambda values. There is no way around that basic truth. The way lambda increases in an F1 engine is by calling up fuel injection maps with shorter injection times. So to compensate for the reduction of fuel flow the driver will need to increase the throttle setting to get back on the same fuel flow at higher lambda.

If you want to compare mass flow at constant throttle and higher lambda obviously the mass flow will go down. This is why people find it difficult to understand the concept.

You are a dangerous man. Verbal gymnastics at it best.
Got to hand it to you though, you're a verbal Houdini.

The mass flow doesn't increase naturally, you held the fuel constant and, made the air increase to get the result you want.
The convention you used is not used by anyone else, and is only made to dispute the fact that a leaner mixture has less mass than a richer mixture of the same amount of air.
You know this already so we'll end this here and get back to the engine talk.

Let me just say this about why your method is not bullet proof; the air demand is variable up to a certain point. At wide open throttle you can't add any more, because of the volumetric efficiency of a natural aspirated engine. All you can do is vary the fuel.
So if you had 68g of fuel and wanted to lean it out to lambda 1.5, and the engine is at WOT , you would not be able to add more air! unless you force air into the engine; that's forced induction.
So what i am trying to say is that the concept of lean/rich is best understood on varying fuel against a fixed amount of air.
Yes air can be varied. But i never saw an ECU that held fuel constant and asked the driver to press the pedal to get the right lambda.
So to cover all engines diesel and gas, you simply vary fuel for different throttle positions, (diesel has fixed air, so your convention doesn't hold there) instead of varying throttle for the same fuel.
That is the convention that is more straight forward.

[WhiteBlue]

I think we have discussed the effects of rich/lean mixtures with conventional and future engine management systems sufficiently.

I hope we get more information soon about the new formula.

[ringo]

Yes, so while we're at it, i think 1.5 lt turbo is very easy to bring back.
It's probably the lazier and cheaper solution.

The rev limit may be around 14,000 rpm with valve spring actuation, but 18,000 may be in reach with the pneumatic valve actuation.

Reason i say this is the lazier easier solution is based on the popularity of turbo charging suzuki hyabusa and GSXR engines. The Busa is 1300cc and GSXR is 1000cc.
Busa goes to 11,000 rpm or there about, and the GSXR goes to 13,500 rpm; which is pretty high.
When they are turboed the rev limit is still maintained.

These bike engines are relatively cheap to manufacture, compared to the current V8 engines. Throwing in the extra research and money to get them up to 18,000 rmp, with good reliability shouldn't be difficult.

[youtube]http://www.youtube.com/watch?v=9LG-DjlrMEg[/youtube]

We may still be able to keep that classic high revving pitch of F1, with the new formula.