Merc engine cracks 20000 rpm!

[Phoenix]

This is interesting. However when using lubrication with bearings, do you have to know befrehand the stress levels that will be experienced in order to get a lubrication that has the porperies that can withstand those loads? And what happens if the lubrication does not withstand? False brinelling? And seizure(sp) of the bearing?

[mep]

Those who say the Mercedes Engine is bad on reliability
tell me one engine failure during a race in this season,
except the Montoya engine at Nürburgring which was
over reved on purpose.

[jgredline]

Those who say the Mercedes Engine is bad on reliability
tell me one engine failure during a race in this season,
except the Montoya engine at Nürburgring which was
over reved on purpose.

Mep How can Montoya over rev an engine on purpose?

[pyry]

wear is probably not the key issue, but id consider stress being it. the acceleration and g-forces applied to the pistons and conrods is pretty dramatically increased, a lot more than 10%. and the cosworth did it on a bench momentarily, whereas the mercedes did it in qualifying. i dont see the cosworth revving 20000 in race or qualifying.

[Strax]

So Mercedes with all their $$$ can achieve only what Cosworth managed several months back ??

At least they managed it, while other manufacturers have clearly not. Do not get me wrong, but you have to give them credit for their improvement.

And also you have to take into consideration all the Cosworth failures. If you can't be reliable, it does not really matter how powerfull your engine is.

[Strax]

Those who say the Mercedes Engine is bad on reliability
tell me one engine failure during a race in this season,
except the Montoya engine at Nürburgring which was
over reved on purpose.

Mep How can Montoya over rev an engine on purpose?

Montoya did not overrev the engine by himself. He was given permission by the team to use maximum revs, although they knew that there was a chance that the engine was not going to last

[pyry]

montoya was on his second race with the engine and outside the points, so there was nothing to lose

[flynfrog]

wear is probably not the key issue, but id consider stress being it. the acceleration and g-forces applied to the pistons and conrods is pretty dramatically increased, a lot more than 10%. and the cosworth did it on a bench momentarily, whereas the mercedes did it in qualifying. i dont see the cosworth revving 20000 in race or qualifying.

agreed those pistons are seeing 9000Gs i think i rember reading at some point that is almost unimaginalbe amount of force

[DaveKillens]

It is an unmanageable force. At present, this is pushing current technology to it's very limits. The engine may be able to safely reach such incredible RPM's, but only for a short time. Through countless hours on the dyno and many broken engine parts, the engineers know how much the engine can take before the odds say that failure is probable. So they try as much as possible to limit those stresses. In practice and when speed isn't critical (first five minutes of the last qualifying session) the engine is kept at lower and safer levels of performance. Only when needed, such as qualifying, the first few laps on a start, and when under pressure, do they allow the driver to turn up the wick, and go into dangerous terrority.

[flynfrog]

It is an unmanageable force. At present, this is pushing current technology to it's very limits. The engine may be able to safely reach such incredible RPM's, but only for a short time. Through countless hours on the dyno and many broken engine parts, the engineers know how much the engine can take before the odds say that failure is probable. So they try as much as possible to limit those stresses. In practice and when speed isn't critical (first five minutes of the last qualifying session) the engine is kept at lower and safer levels of performance. Only when needed, such as qualifying, the first few laps on a start, and when under pressure, do they allow the driver to turn up the wick, and go into dangerous terrority.

its realy pretty amazing how well ballanced on the razors edge the f1 teams are

[Ciro Pabón]

This is interesting. However when using lubrication with bearings, do you have to know befrehand the stress levels that will be experienced in order to get a lubrication that has the porperies that can withstand those loads? And what happens if the lubrication does not withstand? False brinelling? And seizure(sp) of the bearing?

Yes, bearings are designed for the loads they will support. The greater the load, the bigger the thickness of the film and the greater the pressure of oil or air you want to have.

For example, the foil bearing is used on turbines and uses pressurized air. The shaft acts as an air pump creating a thin layer of high pressure air that is captured between the journal and top foil. The bump foil acts as a spring to tailor the compliance of the bearing and minimize air leakage:



There is a relationship between the load the bearing can take and its rotational speed:



To put things in perspective, a microturbine with a foil bearing can withstand 100,000 rpm.

They have been used since 1998. They do not need oil, so they are perfect for ultracold environments or hard to maintain places, like in satellites.



To blow your mind, a meso-turbine, etched in silicone, can withstand 2.5 million rpm. It has 4 mm diameter and should deliver 50 watts in a package about 1 cm3.

In case you are wondering how you can manage to withstand hundreds of megapascals created by centripetal forces, the researchers (the thing hasn't worked yet, that I know) explain that when you construct small structures, they are defect-free. There you have an idea: construct an F1 engine joining around 10.000 mesoturbines. At least you could claim over 2 million rpm...



About the false brinelling: when lubrication fluid (air or oil) is squeezed out, real brinelling can occur: the journal touches the sleeve and produces fragments of metal, fragments that later rust and produce more wear. Of course, the raceway becomes bumpy and the oil has problems flowing over it.

If you see the failure point under the microscope, you see the same indentures and fractures of a hardness test (invented by the swiss Brinell, author of the Brinell scale for hardness).

Brinelling by excesive axial load (just on a side of the raceway):


Flaking by scratches during assembly (take good care of your bearings!):


False brinnelling is a wear that has the same appearance of real brinnelling, but occurs on a stationary engine. For example, when you install generators (a main and a reserve, for example), you have to put them apart. If they are too close, the vibrations from the running generator ruin the bearings of the generator that is turned off. This happens because there is no oil between journals and sleeve on the inactive engine.

False brinelling by stationary vibration:


False brinelling by shock load while stationary (like the cars transported on trains around 1930, that I mentioned in my last post):


If you install the generators too close to each other, the unhappy day you turn on the reserve one, you find it is damaged. In the beginning of bearing "science" this was a mistery: a "new" engine did not work and the bearings showed the marks of brinnelling. This is what is called false brinnelling.

wear is probably not the key issue, but id consider stress being it. the acceleration and g-forces applied to the pistons and conrods is pretty dramatically increased, a lot more than 10%...

I'm not reaaaally sure, but I do not remember an F1 engine failing through rod or piston failure (probably you are going to show me a dozen examples...), a failure I've seen in dragsters. You know, dragsters have real horsepower, not like those puny F1 engines... A couple of top fuel dragsters have almost the same HP as the entire F1 grid (around 15.000 hp).

I wouldn't say 9.000 G's or whatever are unmanageable but simply you weight 9.000 times more. For example, I would weight around 650 Tons, about ten heavy trucks. Ordinary steel can take 60 Tons per square inch, so you could use 10 in2 of steel to hold me under 9.000 Gs. Do not give up so easily! Remember our forum motto (that I'm inventing on the march): "There are no imposible things, only unable men".

Finally: isn't hp a function of rpm and torque? I know it is not a linear function, because of friction, but the basic equation goes like that. Now, if we develop a foil bearing that can take the loads of a piston engine...

[Reca]

This one should be Kimi lap in Q2 at Magny Cours.
http://www.youtube.com/watch?v=wPzA4EXw ... nce%202006

I timed it 1’15”85-9 and looking at the best laps in all the sessions Kimi was capable of going under 1’16” only in Q2 with a best 1’15”7. The couple of tenths discrepancy is most likely related to the fact that I had to use as reference the start line since video footage starts well past the timing line. Consequently at the end of the lap I had to include also the part between timing line (real end of lap) and start line where Kimi wasn’t pushing anymore.

That’s the rpm I obtained from analysis of engine sound :
[IMG:150:133]http://img212.imageshack.us/img212/7070 ... ti4.th.jpg[/img]

The highest rpm, at about 65s, is slightly over 19700. In the remaining parts of the lap the upshift was typically between 19500 and 19600.
The point of peak car speed (before the hairpin) is at about 21-22s, there the engine was running at 18500 rpm, peak power shouldn’t be distant from that rpm (ideally you would set the 7th gear exactly to have peak speed at peak power but there are more things to consider so it’s possible there’s a small difference).

[Powerslide]

I have read that 20,000 rpm can mechanically be achieve a while ago. Its just a matter of getting enough air to breath at that rpm to make it beneficial.

[djos]

Last Time I checked, the Cosworth Engine has been hitting 20,000rpm for most of the year in qually!