F1 engine RPM

[aussiegman]

"Very interested in how you got an estimate of 150Nm? Did you/do you know the weight of the rotating assembly and the exact compression of the engine?"

0.016 kg m^2 just a WAG

Cool!

Compression is an interesting one. Does an engine with the ignition off slow down more quickly with an open throttle or a closed throttle? If you /know/ stay schtum for the time being, if you don't, explain the reasoning for your answer and give a rough guess as to the size of the effect. How much does CR affect it?

You know I had never thoughtabout it! It sounds like one of those riddles is a man going deeper into the forest once he passes half way or is he on his way out??

Never the less here are my drunken pre-international flight thoughts!

Ok firstly a closed throttle would on first blush simply due to the fact the engine would be operating at its lowest available RPM that being idle. If the throttle was open by any % above zero throttle input which is idle speed, then the RPM would be above the idle value and therefore the time to stop should be greater by some determinable amount of time however infinitesimally small. Compression would therefore not be the determining factor, RPM value would be as a result of the increase in the time taken to go from (idle+x)RPM where "x" is a result of a % of throttle input than the time taken to go simply from (idle)RPM where throttle input equals zero %.

However, i think what your trying to actually get at which is if you switched off an engine and then either:
A: left it with zero % throttle input; or
B: a throttle input above zero %

would the increase in throttle % in effect an increase or decrease the time taken for the engine to stop.

So let's set some specifics.

The engine is at the same RPM prior to the switch off;
There is as close to zero time differential between switch of and throttle opening as possible and as such this value is zero
It's an NA engine, no forced induction.
The throttle %'s are either 100% throttle open or zero % throttle input (so what the engine sees at idle) at the time of switch off. So.......

If closed it should be pulling a vacuum against the closed throttle butterfly(s) where valves are open on the intake stroke which would create resistance to motion. However on the compression stroke the cylinder would then be seeing less volume than where the throttle is 100% open as the intake stroke was performed under restricted flow which causes an apparent vacuum. This vacuum should be relative to what the engine pulls at idle so there should still be enough pressure from charge to cause some resistance due to compression.

If the throttle is 100% open then it is drawing down against a lesser restriction on the intake stroke so there is less resistance but not zero resistance to the intake stroke. However it should also have a drawn a larger intake charge volume which requires more work to compress and provides more resistance during compression. Any resistance seen should be in someway relative to the vaccum seen during steady state RPM operation.

There are a number of other variables such as inertia of rotating assemblies, number of cylinders etc, but I am struggling with 9 beers to form any opinion other than it would likely be close to a stalemate.

How much effect does CR have? It determines the amount of force that will be required to compress the intake charge but does not effect intake restriction as that comes from valve area and throttle. On first review, I would have to say CR makes a difference as shown anecdotally by the high oppression engines vs. the forced induction I run. The high CR NA engines takemore to turn over at start and always seem to stop dead on switch off where as the lower CR turbo (not crank driven supercharged) engines are easier on batteries and starter motors and lazier on switch off. If there was no compression then the engine would not be working against any opposing force excepting friction and intake restriction.

I need more time to think about it and a 12 hour flight should be perfect if I'm not sleeping, but if i had to make a (poor) guess and pick one where i couldn't simply convince myself it was a wash which i keep coming back too then throttle closed would be it. But I am in no way confident.

On a directly related note, if the engine is running at 19000 rpm in the garage roughly what MAP is it running?

As this was a number of years ago an allowable map when the max RPM value allowed 19,000RPM. Yes I am old-ish.

[hardingfv32]

So how do you shut off a pneumatic valve system?? Remove either the electrical input that forms part of its operation and/or remove the kinetic energy input that actuates the system.

It would be my opinion that you have no idea what you are talking about. That you use many sentences when one or two will do. Note how you responded to my simple question.

I am not trolling. I am hoping to learn something about pneumatic valve systems that I might not know.

A F1 engine valve train system, or a subset call pneumatic valve system can not be 'turned off' during normal operation, such as during braking deceleration. Your statements do not agree with this claim.

Feel free to demonstrate otherwise.

Brian

[PhillipM]

On a directly related note, if the engine is running at 19000 rpm in the garage roughly what MAP is it running?

As this was a number of years ago an allowable map when the max RPM value allowed 19,000RPM. Yes I am old-ish.

I think that was an epic whoosh-parrot moment there.

[riff_raff]

There is some advantage to using variable delivery pressure with a pneumatic vale spring system. At lower rpms the delivery pressure can be reduced which results in lower peak spring forces and reduced valvetrain frictions.

As for the discussion about engine compression braking with a closed throttle versus an open throttle, as long as the valves are functioning the closed throttle would produce greater braking due to the greatly reduced volumetric efficiency.

And regarding the question about the MAP of an N/A engine running at 19,000 rpm in the garage, the MAP would be quite low, and would depend upon how much throttling was necessary to limit the unloaded engine speed to 19,000 rpm. Of course, if the engine had a fully VVT system, no intake manifold throttling would be required since the intake valves would perform the throttling function.

[Tommy Cookers]

There is some advantage to using variable delivery pressure with a pneumatic vale spring system. At lower rpms the delivery pressure can be reduced which results in lower peak spring forces and reduced valvetrain frictions.

........... is there any engine that does this ??

[autogyro]

Hmm, what is the effect of changing the throttle opening/valve opening on the gear shifts, the gear shift components, the KERS settings and tyre wear?

[jz11]

There is some advantage to using variable delivery pressure with a pneumatic vale spring system. At lower rpms the delivery pressure can be reduced which results in lower peak spring forces and reduced valvetrain frictions.

wouldn't it make sense to leave the pressure as it is in the gas springs in that low rpm range (10-14k), because of the same reasons RedBull used that trick mapping? less power output from the engine in that range - easier for driver to control torque coming out of hairpins?

or is wear and reliability an issue in valve-follower/rocker(if used at all)-camshaft context?

[aussiegman]

It would be my opinion that you have no idea what you are talking about. That you use many sentences when one or two will do. Note how you responded to my simple question.

Brain, it would be my opinion you are a rude, ignorate person who is absolutely unable to read any sentance without performing incredulous leaps of flawed comrehension consistently showing your inability to actually follow a discussion.

Please feel free to point out exactly where my description of a pneumatic valve system was incorrect oh wise one.

Further to this, a question may be short and yet it can require neither a simple nor a short answer, especially given the audience or the person who posed the question. If I had given you a short and simple answer you would have again pulled together further hugely incredulous works of fiction as you constantly do for what can only be assumed is for your own amusement.

I am not trolling. I am hoping to learn something about pneumatic valve systems that I might not know.

Sorry, it is my opinion you are plainly and simply a troll. If not then you need to take a long hard look at yourself! As for learning anything Brian, you seem to be just like an old dog when it comes to trying to learn any new tricks.

A F1 engine valve train system, or a subset call pneumatic valve system can not be 'turned off' during normal operation, such as during braking deceleration.

Firstly, where the hell did I once state or even imply that a pneumatic valve system could be turned off during normal operation? Please feel free to demonstrate exactly where this was stated or implied please Brian.

Further to this, where did I state it could be shut off during braking deceleration? Again Brian, please feel free to demonstrate exactly where this was stated or where anything such as this was implied.

For either case, prove me wrong!

What was said was that where an F1 engine is stopped as in turned off, the system shuts off which included the pneumatic valve system. This is not braking deceleration nor is it what would generally be considered "normal operation" such a racing conditions which is normal for an F1 engine.

As such a normal person would not try and make illogical assumptions as you have that this somehow implies that F1 engines stop or turn off during normal operation or during "braking deceleration"'.

I never implied any such thing and further i stated the workings of a pneumatic valve system and that such system does not shut off in either normal operation or braking deceleration by providing an example of a catastrophic failure which was linked to the valve system effectively turning off. What you have provided Brian is nothing of merit other than that which is purely your work of stupidity.

However what did transpire has been a discussion which you seem totally unable to follow which had many elements, maybe this was to many for you. These included time taken to turn off an F1 engine which you took exception to and where the pneumatic valve system became part of the discussion. Your hyperbolic attempts to link separate unrelated discussions are boardering on the galactically incredulous!!!

Your statements do not agree with this claim.

My statements are based on fact and provable, yours are more akin to deranged works of fiction.

Feel free to demonstrate otherwise.

Brain

You ask for much and provide nothing Brian excepting your inability to follow a discussion and a total lack of common sense which is self evident and as such requires no demonstration from me.

You said I use too many sentences so I will sum up with a single short sentence for you so there can be no misunderstanding:

You are an infant.......

[aussiegman]

There is some advantage to using variable delivery pressure with a pneumatic vale spring system. At lower rpms the delivery pressure can be reduced which results in lower peak spring forces and reduced valvetrain frictions.

As for the discussion about engine compression braking with a closed throttle versus an open throttle, as long as the valves are functioning the closed throttle would produce greater braking due to the greatly reduced volumetric efficiency.

And regarding the question about the MAP of an N/A engine running at 19,000 rpm in the garage, the MAP would be quite low, and would depend upon how much throttling was necessary to limit the unloaded engine speed to 19,000 rpm. Of course, if the engine had a fully VVT system, no intake manifold throttling would be required since the intake valves would perform the throttling function.

So by varying the pressures you could possibly reduce the lift? Do you think the system could react quickly enough to be effective?

[jz11]

you cannot reduce the valve lift in that way, what he was saying, was that, by reducing the pressure, you can make the spring softer, so it is easier for camshaft to push it down, thus reducing the torque required to actually turn the engine, thus increasing the overall power output, but once the cam lobe max lift passes the valve, you want maximum pressure in the spring, so the valve doesn't lag behind the cam profile, or the piston might even "catch" it

thus shutting off air springs in any way while the crank is still turning can cause catastrophic failure, and that is what Brian is hinting at

[aussiegman]

you cannot reduce the valve lift in that way, what he was saying, was that, by reducing the pressure, you can make the spring softer, so it is easier for camshaft to push it down, thus reducing the torque required to actually turn the engine, thus increasing the overall power output, but once the cam lobe max lift passes the valve, you want maximum pressure in the spring, so the valve doesn't lag behind the cam profile, or the piston might even "catch" it

thus shutting off air springs in any way while the crank is still turning can cause catastrophic failure, and that is what Brian is hinting at

That's what I was getting at, i couldn't see how you could remove the mechanical linkage between valve length and cam lift using the traditional pneumatic system.

Softer "springs" reduce parasitic drag agreed, but again I'm not sure you could get the system to react at enough to over come the exact issue of valve float post max lift.

As for what Brian was eluding to, I agree any attempt to shut off the system while the crank was turning would be catastrophic, which is exactly why I provided him with an example such as the failure of the Renault at Sepang for Williams.

[hardingfv32]

I never implied any such thing and further i stated the workings of a pneumatic valve system and that such system does not shut off in either normal operation or braking deceleration by providing an example of a catastrophic failure which was linked to the valve system effectively turning off.

Your are absolutely correct, I missed the change the context of the discussion. Your sure went through a lot to point that out.

I still challenge your statement about a pneumatic valve system shutting off. The loss of pressure in the system is not rapid, possibly measured in hours not minutes after the engine is shut off. An F1 engine can loss all electrical power and coast in gear without damage to the valve train.

Brian

[aussiegman]

I still challenge your statement about a pneumatic valve system shutting off.

Last time on this one then can we please move on.

As explained previously and ad nausium, the systems shut off which includes the pneumatic valve system ECU's, solinoids etc. It was never said or implied that the pressures were dropped. Or increased for that matter which may make more sense as it would increase the time taken for the system to fully discharge due to leakage as well as increasing resistance to rotation.

I am at a loss as to why this is an issue for you to understand.

The loss of pressure in the system is not rapid, possibly measured in hours not minutes after the engine is shut off. An F1 engine can loss all electrical power and coast in gear without damage to the valve train.

As per my description posted previously...

The pneumatic systems suffer some pressure leakage during use that necessitates cars carry nitrogen reservoir at around 2500psi to top off the system as pressures drop through operation cycle.

As per my previous post(s), i am aware of the issues with leakage of the chamber seals. Again I never indicated or implied the removal of electrical power would result in the pressure loss of the system. It is actually the opposite with the system designed to hold pressure and that it "fails closed" where that if electrics were to be cut/fail it would hold pressure as long as the seals last. This would indeed likely be measured in hours not seconds or minutes and again as indicated in previous posts requires external pressurisation when an engine change or transport is undertaken to prevent the valves dropping and touching the piston crowns.

[strad]

So by varying the pressures you could possibly reduce the lift? Do you think the system could react quickly enough to be effective?

Dream on...I seriously doubt that, and I'm sure you don't believe it either.

[hardingfv32]

... again as indicated in previous posts requires external pressurisation when an engine change or transport is undertaken to prevent the valves dropping and touching the piston crowns.

Might the system seal on the valve stem keep the valve in place and prevent it from falling?

Brian