F1technical.net

321apex wrote: - WRC rally formula is based upon restricting the air flow RATE into the engine.
- F1 limits the fuel flow RATE as well as the QUANTITY consumed.
These are fundamental differences, which set the optimization logic and consequently control methods apart.

"snip"

Sorry, I missed the bit where you explained that by changing boost levels you cant change peak power position on the rpm scale, but only on an f1 engine (right?)

On an NA engine cam timing is more important as it is the main control of the air into and out of the chambers, on a turbo engine you can vary the density of the air to control how much gets into the chambers, rather than just the volume.

mrluke wrote:

321apex wrote: - WRC rally formula is based upon restricting the air flow RATE into the engine.
- F1 limits the fuel flow RATE as well as the QUANTITY consumed.
These are fundamental differences, which set the optimization logic and consequently control methods apart.

"snip"

Sorry, I missed the bit where you explained that by changing boost levels you cant change peak power position on the rpm scale, but only on an f1 engine (right?)

On an NA engine cam timing is more important as it is the main control of the air into and out of the chambers, on a turbo engine you can vary the density of the air to control how much gets into the chambers, rather than just the volume.

In the link describing "choked flow" there is a fundamental relationship explained of a ratio of stagnant pressures before and after the restriction.
http://en.wikipedia.org/wiki/Choked_flow
When an engine "runs out of breath" it is usually due to this "choked flow" effect thru the valve/seat curtain area. If it is inlet curtain area the stagnant pressure delta is approx. 0.528. At such condition, Mach speed of 1 is reached and flow mass rate can not increase.

This "choked flow" is also tied with piston/engine speed and Mach index on the inlet cycle down stroke, as is explained in this link:
http://books.google.pl/books?id=UtxI5gX ... ne&f=false

It is important to note that this phenomena is based upon a ratio of stagnant pressures before and after the restriction. So that it's occurrence is piston speed based and not manifold pressure.
p(u)/p(d)=0.528

To illustrate, if you have a turbocharged, unrestricted engine and you dyno test it at some level amount of boost across the rev band. As an example the engine may reach peak power at say 7000 RPM, after which it just falls off. If you were to strip away the turbocharger and if possible not altering inlet/exhaust tract geometry run that same engine as naturally aspirated.
The power peak would occur at just about the same RPM within +/-150 revs.

In both cases, the "choked flow" would coincide at similar piston speed, which is subordinate to Mach index on the piston inlet cycle down stroke. Usually cam lift and timing is most effective in altering rev band location of power peak. It effectively alters the Mach index relationship.

In closing, I must add that similar effects may take place on the exhaust side first. The principle remains the same, however the properties of exhaust gas are much different than air and so a different Mach index threshold would result as well as different numeric pressure ratio before the "choked flow" is reached.

CBeck113 wrote:Here, to help the discussion, is a chart of the free forces which excite motors and should / must be dealt with in order to make it run smoothly (i.e. prolong its life):
http://i.imgur.com/KSZIQDH.jpg?1

Sorry it's German, but I think everyone will understand it.

good info..please give english version, I'm not understand".

Ceramic bearings are extremely tolerant of lack of lubrication.

Letting turbo to run own is mostly about reducing thermal stress by getting it to cool down slower and evenly IIRC.

thisisatest wrote:Ceramic bearings are extremely tolerant of lack of lubrication.

Aha OK, this makes sense.
Seems they use such bearings, as a friction bearing (which I had always thought they would use) for sure would not be happy without oil pressure...

Did somebody know what are the RPM of th MGU-H and the trubo charger?

Mr.G wrote:Did somebody know what are the RPM of th MGU-H and the trubo charger?

The turbo spins at 100.000 RPM. The H is spinning at something less but I think this depends more on the circuit the're at.

I'm asking because I'm wonder what kind of gearing they use to slow down the MGU-H revs.

mycadcae wrote:
good info..please give english version, I'm not understand".

This should help:
http://www.google.pl/url?sa=t&rct=j&q=& ... 5280,d.ZGU

Mr.G wrote:Did somebody know what are the RPM of th MGU-H and the trubo charger?

The rotational speed of the MGU-K may not exceed 50,000rpm.
The rotational speed of the MGU-H may not exceed 125,000rpm.

stefan_ wrote:

Mr.G wrote:Did somebody know what are the RPM of th MGU-H and the trubo charger?

The turbo spins at 100.000 RPM. The H is spinning at something less but I think this depends more on the circuit the're at.

i thought the turbo and the MGU H were on a common shaft? ie they have the same rotational speed.

Crabbia wrote:

stefan_ wrote:

Mr.G wrote:Did somebody know what are the RPM of th MGU-H and the trubo charger?

The turbo spins at 100.000 RPM. The H is spinning at something less but I think this depends more on the circuit the're at.

i thought the turbo and the MGU H were on a common shaft? ie they have the same rotational speed.

not neceserly, could be SINGLE gear ratio. But still electromotor most not eceed 125 kRPM.

321apex wrote:To illustrate, if you have a turbocharged, unrestricted engine and you dyno test it at some level amount of boost across the rev band. As an example the engine may reach peak power at say 7000 RPM, after which it just falls off. If you were to strip away the turbocharger and if possible not altering inlet/exhaust tract geometry run that same engine as naturally aspirated.
The power peak would occur at just about the same RPM within +/-150 revs.

Okay so lets take the same engine, reprofile the boost so we have say 3 bar at 5krpm and 1bar at 7k. You are certain that more power will be made at 7k?

A more practical / realistic example, you might have an engine with peak trq at 4krpm, NA it makes peak power between 4k-5k and tails off to an untroubled redline of 7k. By going FI you might still be building boost by 5k and could make peak power at 6-7krpm.

Running the same level of boost across the whole rev range would just accentuate the engines NA characterics, you cannot do this with a single turbo, especially a big one.

stefan_ wrote:

Mr.G wrote:Did somebody know what are the RPM of th MGU-H and the trubo charger?

The turbo spins at 100.000 RPM. The H is spinning at something less but I think this depends more on the circuit the're at.

Can you provide where you get these numbers from? Please