Ferrari Power Unit Hardware & Software

[saviour stivala]

Video evidence suggests the engine remains clutched to the gearbox most or all of the time. Engine braking is audible which would suggest the ICE isn't being disconnected to run solely as a combustor. But the effect might still be partially achievable without clutch disengagement. Speculatively: part-throttle and zero-throttle modes could simply represent a transition from piston power priority to gas-generation priority, via ignition and injection timing. High throttle and full throttle is low-backpressure, supercharged,and K-boosted mode with earlier timing. Part and zero throttle is compounding mode with later timing and/or cylinder cutting. The sweep of the throttle pedal alters myriad processes within these complex power units.

As far as I know when the formula one car is stationery and the engine is started when the driver opens the clutch (pulls on the clutch paddle) first gear is automatically selected unless the driver selects reverse gear by push button on steering wheel. On the other hand when the car is on the move if the driver opens the clutch/pulls on the clutch paddle the gearbox will automatically drop into neutral. The driver does not use the clutch when changing gear up or down. Applying both throttle and brake pedals together using both feet is nowadays used to harvest energy by the K by burning fuel, but there is the risk that if the driver uses the brake pedal hard he will trigger the failsafe algorithm which is designed to over-ride the throttle and cut the engine. (This was something that failed/was inhibited by the torque coordinator, which controls the rear brake-by-wire system on both Marussia’s tragic accidents).

[Dr. Acula]

So you are suggesting that during braking, the driver can step on both brake and throttle, pull in the clutch, put the MGUK in harvest mode, and rev the engine and load the MGUH.. this makes sense. Burns gas, but if fuel is not a problem in qualifying, then its very viable.
In the race they can still do this technique.

The clutches they run in F1 are not designed to be disengaged/engaged multiple times per lap. They would burn up in no time if you would try this.
In a normal, uneventful race a driver uses the clutch only on 3 occasions. On start of the formation lap and race, when he's in the pits and when the race has ended and the clutches in F1 are designed with this in mind.

[saviour stivala]

So you are suggesting that during braking, the driver can step on both brake and throttle, pull in the clutch, put the MGUK in harvest mode, and rev the engine and load the MGUH.. this makes sense. Burns gas, but if fuel is not a problem in qualifying, then its very viable.
In the race they can still do this technique.

The clutches they run in F1 are not designed to be disengaged/engaged multiple times per lap. They would burn up in no time if you would try this.
In a normal, uneventful race a driver uses the clutch only on 3 occasions. On start of the formation lap and race, when he's in the pits and when the race has ended and the clutches in F1 are designed with this in mind.

Fully agree, that the f1 clutches are not designed to be disengaged/engaged multiple times by the driver and that they would burn up in no time. the clutch can be used multiple times on down shifts but only automatically by the downshift computerized system and not by the driver, No human being have the necessary reaction to use the clutch in such a fast way for the clutch to last for any length of time. On upshifts the clutch is not used at all, only a throttle blip is needed, and that throttle blip is achieved by ignition cut off and on.

[ringo]

Well maybe special clutches are designed for this year's engines. Lower engine speeds these days, at 11,000 rpm to so less stress there. I don't see this as a big challenge for the engineers.
This strategy will be done during braking, where the load will be the MGUH and the engine ran against the MGUH to charge the ES. This will ensure that more than enough energy is stored to provide power for super charging and driving the mguk when needed.
The wastegate will be closed.
Engine loaded against the MGUH up to predetermined engine speeds.
MGUK energy to ICE to MGUH i suppose during this process?

Also we tend to ignore that the rev limit is 15,000 rpm. Max power is made around 10,500 of course, but revving above can provide an envelop for providing additional charging for the MGUH. I would like to see how high the ferrari engine revs during Q and the race.

[roon]

Let's call it genset mode. Possible, but the exhaust note varies with downshifts during braking in every SF71H recording I've heard. Which implies the clutch isn't disengaged. I don't think rev matching and clutch operation should be especially problematic.

Work on friction and pumping efficiency should enable higher engine speeds without compromising power. Perhaps higher exhaust frequency benefits turbine operation. I haven't seen any tachometer readings on the broadcasts this year. Anyone know anything about engine speeds in 2018?

[Tommy Cookers]

PU overrun 'push' is capped at zero PU output torque (is overrun even defined ?)
zero PU output torque with the K loading the crankshaft to be outputting at 120 kW to the DC line
while the H loading the crankshaft via a high exhaust pressure and outputting at its maximum power to the DC line

and no particular need for unusually high ICE rpm
and no need for the clutch to be open

[saviour stivala]

If the H is harvesting there is no scope in the K to H supply.
the engine cannot produce any additional power above max power speed (10500rpm).
most probably these turbo engines use a maximum RPM above the max power speed of double that which the NA 2.4l v8 had which was 500RPM.

[Dr. Acula]

Well maybe special clutches are designed for this year's engines. Lower engine speeds these days, at 11,000 rpm to so less stress there. I don't see this as a big challenge for the engineers.
This strategy will be done during braking, where the load will be the MGUH and the engine ran against the MGUH to charge the ES. This will ensure that more than enough energy is stored to provide power for super charging and driving the mguk when needed.
The wastegate will be closed.
Engine loaded against the MGUH up to predetermined engine speeds.
MGUK energy to ICE to MGUH i suppose during this process?

Also we tend to ignore that the rev limit is 15,000 rpm. Max power is made around 10,500 of course, but revving above can provide an envelop for providing additional charging for the MGUH. I would like to see how high the ferrari engine revs during Q and the race.

It's not a technical challenge at all, but why make something bigger and heavier than you have to.

Also, to disengage the clutch under braking would be stupid. The MGU-K is attached to the engine. So the moment you brake and disengage the clutch, you would waste all the kinetic energy of the cars mass for what exactly? Extra energy? i doubt that the MGU-H under these circumstances would produce more electrical power than the MGU-K would with it's 120kW. I think we all know about the solution Honda worked out to circumvent the 2MJ charge limit of the MGU-K to the ES. Why would they do this if it would be more efficient to disengage the clutch and burn some of the limited amount of fuel for a bit of extra energy?

And one other thing.

5.6 Power unit control :
5.6.1 The maximum delay allowed, computed from the respective signals as recorded by the ADR or ECU, between the accelerator pedal position input signal and the corresponding output demands being achieved is 50ms.
5.6.2 Teams may be required to demonstrate the accuracy of the power unit configurations used by the ECU.
5.6.3 Power unit control must not be influenced by clutch position, movement or operation.
5.6.4 The idle speed control target may not exceed 4,000rpm.
5.6.5 A number of power unit protections are available in the ECU.
A minimum of nine seconds hold time should be configured for the power unit protections enabled during qualifying and race. The configuration of the air tray fire detection and throttle failsafe are exceptionally unrestricted in order to allow each team to achieve the best level of safety.
5.6.6 The power unit must achieve the torque demanded by the FIA standard software.
5.6.7 Homologated sensors must be fitted which measure the torque generated at the power unit output shaft and the torques supplied to each driveshaft. These signals must be provided to the ECU.

Art.5.6.3 basically prevents your idea. Because the PU is not allowed to go into a special mode by pulling the clutch lever.

[Zynerji]

Dumb question without really thinking about it too hard, but would up shifting the gear box right before braking put a higher rpm back through the engine/mguk?

Obviously wouldn't work on long straights in 8th gear, but if the k is doing most of the engine braking, wouldn't putting it into a higher ratio during the braking phase put more energy from the rear wheels into the k?

[Dr. Acula]

Dumb question without really thinking about it too hard, but would up shifting the gear box right before braking put a higher rpm back through the engine/mguk?

Obviously wouldn't work on long straights in 8th gear, but if the k is doing most of the engine braking, wouldn't putting it into a higher ratio during the braking phase put more energy from the rear wheels into the k?

No and no.
To get higher engine/MGU-K rpm at the same speed, you would have to shift down, not shift up.

Gear ratios don't change the amount of power. A gearbox can exchange rpm for torque and vice versa, but power stays always the same. In an ideal world the same amount of power which goes into one end of a gearbox comes out the other end.

[Zynerji]

Ok. So upshifting during braking would lower the RPM of the ICE/MGUK, but increase torque...

Any advantages in the mgu recovery by raising the torque spinning the electric motor, or is rpm more important than torque for recovery?

[roon]

Dumb question without really thinking about it too hard...

Hey, that's my territory. Anyway, engine braking should increase with RPM, so maybe this is something to consider. Or, more generally: downshifting through the upper RPM range that would never be used for acceleration. Downshifting earlier, essentially. This should give more air to the turbine, depending on what the compressor and throttle 'plates' are doing. Consider: open throttles during braking (which would reduce the engine-braking effect) combined with early downshifts to increase mass flow to the turbine. MGUK will aid in replacing the loss of the engine-braking feel. This cold-blowing of the turbine by the engine could be accentuated by late ignition and injection, if need be, to heat the air arriving to the turbine without significantly increasing cylinder pressure. So I would, within this line of thought, suggest somewhat the opposite: downshift as soon as possible when braking. And keep downshifting earlier than you normally would.

Maybe this partly informed the 15k RPM engine speed limit rule. They knew that acceleration RPM would never be much higher than where the peak fuel flow limit was set, and they would have forseen the engines being used as high-RPM air pumps under braking. 10,5k RPM on the throttle, 20k RPM on the brakes. What could have been...

[roon]

A forum member made this video (can't find OP):

At 0:00-0:02, a Force India passes, making a distinct sound. Presumably this is how the Merc power unit sounds with the wastegates open.
At 0:06-0:09 a very similar sound occurs when a factory Mercedes passes. A Sauber is near to it but is inaudible.
At 0:02-0:04 two Renault-engined cars pass, they are distinctly the quietest, seemingly no wastegate opening.

The last car in the vid is the SF71H making it's distinctive wastegate sound. It sounds smoother and higher pitch, more of a relief-valve sound of pressurized gas escaping.

Some annotations to an F1i.com image:



I presume the 'mystery manifold' is conveying either oil or coolant. It has six ports corresponding to the six exhaust valve locations.

[sosic2121]

Hey, that's my territory. Anyway, engine braking should increase with RPM, so maybe this is something to consider. Or, more generally: downshifting through the upper RPM range that would never be used for acceleration. Downshifting earlier, essentially. This should give more air to the turbine, depending on what the compressor and throttle 'plates' are doing. Consider: open throttles during braking (which would reduce the engine-braking effect) combined with early downshifts to increase mass flow to the turbine. MGUK will aid in replacing the loss of the engine-braking feel. This cold-blowing of the turbine by the engine could be accentuated by late ignition and injection, if need be, to heat the air arriving to the turbine without significantly increasing cylinder pressure. So I would, within this line of thought, suggest somewhat the opposite: downshift as soon as possible when braking. And keep downshifting earlier than you normally would.

I agree with you.
Is it allowed to have throttle bodies open while breaking?

[saviour stivala]

"Consider open throttle under braking".
Hungary FP1, Vndoorne to pit wall: “I have no deployment”.
Pit wall to Vendorne: “Don’t brake to hard against throttle”.
Applying both throttle and brake together using both feet, will trigger the rear brake by-wire failsafe system. The failsafe algorithm is designed to override the throttle and cut the engine by the torque coordinator which controls the rear brake-by-wire system.