What will come after the 2.4 V8?

[xpensive]

God damnit WB, I told you to keep away from the technical stuff!

[raymondu999]

Not quite "engine related" per se, but even Nascar is going solar!! http://www.wired.com/autopia/2010/07/na ... lar-power/

[madtown77]

If you avoid the throttle all together (for efficiency reasons) you get the full gas flow going through the engine. This is what people want for the blown diffusors.

Hmmm... i definitely have no clue what you're talking about, do you have a link to the source you got this idea from? that may help me.
You can't avoid the throttle, whether you use a plate or valve lift and timing to throttle an engine, you still need to throttle it, otherwise the partial load term wouldn't even exist, you'd be at WOT all the time.

A agree with you on the "full gas flow", not sure I understand.

You can remove the throttle if you could control the valves well enough in theory. Opening the valves for a shorter time, or if you have HCCI, injecting less fuel, would both allow you to control engine load.

For other readers. This also makes me think about the vacuum a race engine produces, perhaps someone with engine knowledge may be able to answer this. Given the aggressive cams/huge valve overlap of a racing engine, your vacuum signal is always extremely low, i can only imagine that on an 18k optimized setup it will be minimal. So with this in mind, would you gain anything by using valvetrain as a throttle device on an engine that spends most of its time at full throttle? could you really offset the increased mass and friction (which again BMW hasn't gotten to make sense past 6k rpms) on an F1 application?

Can't have it both ways. Removing the throttle helps at part load conditions more than at fully loaded conditions of course, but even a race engine spends time at part throttle. Won't hurt and in terms of advancing engine technology (which I think will be part of the aim in the new regs) its a good idea.

*EDIT: Also, remember that even a fully open throttle is not lossless. Lot of turbulence at high air velocities on a throttle blade.

[WhiteBlue]

If you avoid the throttle all together (for efficiency reasons) you get the full gas flow going through the engine. This is what people want for the blown diffusors.

Hmmm... i definitely have no clue what you're talking about, do you have a link to the source you got this idea from? that may help me.

I have already quoted this source three pages before. Please read this to get an idea for throttle less engine management and how to avoid or reduce pumping losses.

Throttling the air flow through an engine will soon look so antiquated as a carburetor now does compared to an injection pump. With solenoid valves, direct stratified injection, ion current measuring and narrow combustion window fuels things will soon look different.

Regarding turbo and rpm have a look at the diesels. They make the power from torque which is an option for petrol engines as well. The engineers and the rule makers will have an option if they get the target power of 600 bhp from revs or turbo pressure.

Well all engines make power from torque and rpms, can't have one without the other really.
I'm at a loss as to what you're saying.

What I'm referring to is the lack of the option for racing diesel's to use extremely high revs compared to the ignited petrol engines. Diesels have to stop with increasing the revs at one point and continue to get more power from capacity and load pressure. So diesel engineers probably have researched the technical resources for these (high pressure stratified direct injection, Variable geometry and multi turbos) much better.

[alelanza]

A agree with you on the "full gas flow", not sure I understand.

Yeah, i'll wait for WB's explanation on that one

You can remove the throttle if you could control the valves well enough in theory.

In practice as well, BMW has been doing that for a while in production vehicles, it's the valvetronic stuff i referred to a few posts ago. I think other manufacturers do it as well, and i also believe it does not work in all part throttle conditions, ie they still have a throttle plate for certain scenarios.

Can't have it both ways. Removing the throttle helps at part load conditions more than at fully loaded conditions of course, but even a race engine spends time at part throttle. Won't hurt and in terms of advancing engine technology (which I think will be part of the aim in the new regs) its a good idea.

I agree with you that it's a good idea. But my question is, is it a good idea for F1? If a big (though perhaps not huge) manufacturer such as BMW hasn't gotten the technology to work in their street performance applications, how would F1 teams with much less $ and a much different focus get it to work?
We know the problem of partial throttle is pressure differential between both sides of the piston, thus i ask, on a racing engine with a much lower vacuum signal than that of a sub 6K rpm street and thus (I think) more efficient at partial throttle, would you truly gain anything?
BMW says their system stops being efficient past 6k due to the friction losses incurred by the larger valve train. Now i'm not sure if that info is up to date, the system has been in use since 2001 after all. But this makes me think, and please correct me if i'm wrong, that if you have less to gain due to less vacuum then on a racing engine this system would stop being efficient at much lower revs. Of course I'm pretty sure valvetronic is not the only solution out there, thus why I ask what kind of setup would make sense on an F1 engine.
Otherwise i feel it's another example of people asking for street car technology to be transferred to F1 just for the hell of it, losing sight of the profound differences between their grocery getter and what should be a firebreathing monster in 4 wheels set out to entertain us 19 times a year. In fact, when you get down to it 4 wheels are about the only thing they share in common hehe.

*EDIT: Also, remember that even a fully open throttle is not lossless. Lot of turbulence at high air velocities on a throttle blade.

True, but if we use the valves to throttle the system, we'll also get a pretty decent degree of turbulence in the air swirling around the moving valves, so not lossless either, correct?

What I'm referring to is the lack of the option for racing diesel's to use extremely high revs compared to the ignited petrol engines. Diesels have to stop with increasing the revs at one point and continue to get more power from capacity and load pressure. So diesel engineers probably have researched the technical resources for these (high pressure stratified direct injection, Variable geometry and multi turbos) much better.

Gotcha, i guess it was the word 'reserve' that threw me off. Also i didn't realize we were talking about diesels, it was a few days since i had visited this topic.

So what about the 'full gas flow going through the engine' thingy? i'm still lost on that one.

[madtown77]

*EDIT: Also, remember that even a fully open throttle is not lossless. Lot of turbulence at high air velocities on a throttle blade.

True, but if we use the valves to throttle the system, we'll also get a pretty decent degree of turbulence in the air swirling around the moving valves, so not lossless either, correct?

Valve turbulence is a property of the valve. Anything you can do before then to reduce pressure drop will help you. I'm not saying it makes the system lossless, but it takes out a large turbulence source upstream of the intake which is of huge benefit even at a fully loaded condition.

Won't know what possibilities exist in variable valve technology until it gets pushed to its limits. F1 is as good a place as any for that kind of development.

[WhiteBlue]

A agree with you on the "full gas flow", not sure I understand.

Yeah, i'll wait for WB's explanation on that one.

I thought that was pretty obvious from reading the source I gave. With a throttle the power modulation is done by reducing the air or oxygen flow through the engine. This means you have a reduced efficiency and reduced gas flow.

If you use advanced methods of power modulation you can achieve partial load conditions by leaner burning, variable ignition timing, exhaust recycling, valve time variations and by the direct injection technology. It means you will achieve higher gas flow through the engine which is something the blown diffusor likes.

[xpensive]

But what is interesting for the diffuser is the gas-flow out of the engine, which always will be a result of the amount of fuel burnt, if you don't burn any fuel I cannot possibly see what difference a throttle-less engine will make?

[madtown77]

If you can run under lean A/F ratios you would get higher gas flow through the engine. If you could run it out to like lambda of 2, you theoretically get twice the gas flow. As I said a few pages back this is possible, but has not been done in an automotive application to my knowledge.

[alelanza]

I thought that was pretty obvious from reading the source I gave.

There's no sense in being subtle with you is there?

But what is interesting for the diffuser is the gas-flow out of the engine

Exactly

If you can run under lean A/F ratios you would get higher gas flow through the engine. If you could run it out to like lambda of 2, you theoretically get twice the gas flow. As I said a few pages back this is possible, but has not been done in an automotive application to my knowledge.

Interesting, I didn't know the leaner mix produced more flow, why is that? And does having more mass flow means you're less eficient? ie more of the combustion energy is going towards the exhaust?

But back to the point, do you need to eliminate the throttle plate to achieve said lean condition? can't see why you would have to, but i'm open to new well fundamented ideas.

[WhiteBlue]

But what is interesting for the diffuser is the gas-flow out of the engine, which always will be a result of the amount of fuel burnt, if you don't burn any fuel I cannot possibly see what difference a throttle-less engine will make?

The amount of gas flow out of the engine is very well dependent of the use of a throttle. Let us assume that we use the same amount of fuel for throttle and throttle less operation.



Now keep in mind that most of the gas passing through the engine - in fact 80% - does nothing at all for combustion. It goes in and goes out without doing anything.

In throttle less operation the engine sucks in a lot more air say 30% - because it is not throttled - and burns the fuel under stoechiometric.

In throttled operation the engine sucks in less air and burns it closer to the stoechiometric relation. It is most likely not over stoechiometric.

If we compare our mass flows we get hugely more nitrogen coming out of the throttle less engine. We get the same amount of burned fuel gas and in the case of the throttle less engine we get residual oxygen in the exhaust. So we get a higher gas flow from nitrogen and oxygen. QED

[machin]

Just to clarify for other readers (as I didn't think it was clear from the post): What WB says is true for Diesel engines... where you can operate without a throttle and simply inject less fuel, but for a petrol engine injecting less fuel results in really high combustion temperatures and very short component lives... to remove the throttle plate from a petrol engine you have to re-introduce a throttle in another way (I think WB suggests using variable valve lift to achieve this), but this means that you don't get the effect he has described above.

Also, its worth bearing in mind that a turbo diesel engine sucks in far more air at full load (i.e higher injection quantities) than at low loads (low injection quantities) because the turbocharger will be working harder due to the higher exhaust temperatures (i.e. producing higher intake gas flow, and hence exhaust gas flow)... so even an unthrottled turbocharged diesel has a much higher exhaust gas flow at high load than at low load, so there's no easy solution to obtaining a constant exhaust flow for the diffuser....

[WhiteBlue]

It is true for petrol and diesel. Throttle less operation will give you more gas flow all other things being equal. It will also reduce pumping losses and therefore consume less power from the other working strokes. It means that the engine will produce more power all other things being equal.

[machin]

Throttle less operation will give you more gas flow all other things being equal

I couldn't agree with you more... however if you don't have some other way of limiting the air going into a petrol engine (e.g. by reducing valve lift for example) how will you avoid the very high high:fuel ratios at part load situations that will result in extreme temperatures and failed valves and pistons?

Throttle-less petrol engines (combined with another form of metering air for part loads situations) at full load do have a slightly higher air flow capacity than throttled engines at WOT (all things being equal) as there isn't the flow restriction of the throttle butterfly, but it only has a very small benefit at part load situations where you need another form of air metering to avoid the high temperature discussed above.

I agree that Throttle-less petrol engines are the future... but they're not going to help the blow diffuser issue.....

[WhiteBlue]

I can only go by what I have read about it and the sources are not clear about under stoechiometric combustion. So if I follow your point that free oxygen would be damaging to the engine one would probably only have the chance to reduce the air volume flow by valve timing and exhaust gas recycling. In both cases you would be right that this would not help the EBD. Unless they find a way to make the valves resistant against hot oxygen they will probably have to do the trick with the over stoechiometric combustion in the exhaust system that they do now. That would obviously waste a lot of fuel. So the point goes to you for pointing it out.