Ferrari Power Unit Hardware & Software

[Tommy Cookers]

I wonder then why doesn't Mr VanDoorne say 'my engine has cut !' ?

and ....
if the throttles are closed at rather high rpm the ICE will give a resisting torque of about 14% of its maximum torque at that rpm
(about 4% from the throttle closure and about 10% from the engine friction)

so towards the end of braking closed throttles would be stealing substantial kinetic energy recovery from the K
and remember KE recovery ceases when the rear axle grip falls below 120 kW worth of resisting torque

clearly (Limbeer paper and Honda telemetry) show ICE-powered K recovery when KE recovery ends and braking continues
the ICE can give 120 kW worth of torque to the K and zero to the rear axle (as in the last NA years)
the ICE could add work against a high H backpressure for further (H) recovery still with zero torque to the rear axle

[Red Rock Mutley]

A forum member made this video...
https://youtu.be/nLdtPx_kvAU

I can't decide whether the car is traction limited when making that harsh noise. I can hear a distinct, momentary phase, when the throttle is initially picked up. That's around, or just after the apex when the engine briefly makes the more usual tone. A fraction of a second later, the harsh tone kicks in and lasts until out on the exit curbing

[saviour stivala]

In Hungary FP1 when Vandoorne was braking against throttle (a bit too hard) (braking against throttle to harvest because only when brake pedal is used can the K go into harvest) the rear brake-by-wire failsafe system momentarily cut-off the engine but because he wasn’t braking hard enough to get the car to a stop his engine anti stall kicked in. if it didn’t he would have ended with a stalled car.
Vandoorne’s rear brake-by-wire failsafe system worked perfectly as intended, after the Marussia/Velota, Marussia/Bianchi tragic accidents (read FIA Bianchi accident expert panel report) nobody will take the risk of playing with such build-in failsafe systems for a gain on track.

[Nonserviam85]

I appreciate the information. I read the entire paper. Interesting the optimal race strategy didn't use the full K allotment. It also shows the 2MJ K regen limit isn't met on track based on brake regen only.

What I also find interesting is how the deployment strategy changed after 2017 when the braking points became shorter due to the new aero regs.

Yes, and more throttle due to increase in drag. Honda said it's partially what prompted them to come up with the extra harvest mode.

I suspect MGU-H is much more important than the MGU-K now.

[roon]

A forum member made this video...
https://youtu.be/nLdtPx_kvAU

I can't decide whether the car is traction limited when making that harsh noise. I can hear a distinct, momentary phase, when the throttle is initially picked up. That's around, or just after the apex when the engine briefly makes the more usual tone. A fraction of a second later, the harsh tone kicks in and lasts until out on the exit curbing

The wastegate sound itself is also unique. It is smoother and more continuous than the Mercedes, which has a distinct and familiar exhaust note like you'd expect from a six-cylinder engine. "Brrrm." The SF71H is more of a "p-sheooo" sound; like a pressure vessel being vented, overlayed upon what is still a relatively quiet ICE exhaust note. Still the engine exhaust note is muted. The only sound that increases is the "p-sheooo." What may be the source of this?

[saviour stivala]

What I also find interesting is how the deployment strategy changed after 2017 when the braking points became shorter due to the new aero regs.

Yes, and more throttle due to increase in drag. Honda said it's partially what prompted them to come up with the extra harvest mode.

I suspect MGU-H is much more important than the MGU-K now.

As regards harvesting the MGU-H was always going to be more important than the MGU-K, because the H is not limited in harvesting.

[timbo]

A forum member made this video...
https://youtu.be/nLdtPx_kvAU

I can't decide whether the car is traction limited when making that harsh noise. I can hear a distinct, momentary phase, when the throttle is initially picked up. That's around, or just after the apex when the engine briefly makes the more usual tone. A fraction of a second later, the harsh tone kicks in and lasts until out on the exit curbing

The wastegate sound itself is also unique. It is smoother and more continuous than the Mercedes, which has a distinct and familiar exhaust note like you'd expect from a six-cylinder engine. "Brrrm." The SF71H is more of a "p-sheooo" sound; like a pressure vessel being vented, overlayed upon what is still a relatively quiet ICE exhaust note. Still the exhaust note is muted. The only sound that increases is the "p-sheooo." What may be the source of this?

Can it simply be an acoustic phenomenon? On the FP in Hockenheim when we've seen a "shotgun" exhausts, one of the pipes was simply an addon to another. I suspect this is still the case in the normal arrangement. So can it be that they somehow have acoustically tuned wastegate exhausts for some reason? This will provide frequency filtering and smoothing of the sound, so from "bang" you'd go to "sheeoooo".

[roon]

Can it simply be an acoustic phenomenon? On the FP in Hockenheim when we've seen a "shotgun" exhausts, one of the pipes was simply an addon to another. I suspect this is still the case in the normal arrangement. So can it be that they somehow have acoustically tuned wastegate exhausts for some reason? This will provide frequency filtering and smoothing of the sound, so from "bang" you'd go to "sheeoooo".

The normal wastegate pipe arrangement seems to be a wye or wishbone shape branching from a single location, with two equal length pipes running alongside the main pipe. Visible in the photos below. The integration of the wastegate may also be worth considering. Seemingly it is built into the turbine scroll housing. However, there aren't really any rules defining what a wastegate is, or how it should be designed or arranged. They're free to put this variable-geometry device in an exhaust system that is not supposed to have variable geometry. Perhaps they're having fun with it.

[saviour stivala]

The formula 1 turbocharger is not a normal turbocharger.
The normal turbocharger will in most cases have the waste-gate build into the turbine scroll, the design aim of which is to control boost by relieving exhaust gases pressure inside the turbine scroll, in doing so it relieves pressure inside the turbine scroll by internally bypassing exhaust gases straight to turbine scroll exhaust outlet.
The formula 1 turbocharger waste-gate cannot be build into the turbine scroll because the design aim is not that of controlling the compressor boost but to bypass exhaust gases away from the turbine scroll relieving turbine scroll pressure so as the compressor can get to and maintain maximum boost by electric supercharging.

[Tommy Cookers]

you pointed out that the wastegate 2 pipe exhaust is limited to a particular (quite small imo) pipe diameter
does this small diameter ever give less than full relief to the pressure seen by the turbine when the wastgate is in operation ?

we might consider relief of mean exhaust pressure and .....
relief of exhaust 'pulse' activity (which anyway exists at ambient pressure as Wright showed in 14000 engines)

diameter-restricted tailpipes have been enhancing pulse activity in performance 2 stroke engines since 1953
the designer's choice not the rulemaker's

[hurril]

The formula 1 turbocharger is not a normal turbocharger.
The normal turbocharger will in most cases have the waste-gate build into the turbine scroll, the design aim of which is to control boost by relieving exhaust gases pressure inside the turbine scroll, in doing so it relieves pressure inside the turbine scroll by internally bypassing exhaust gases straight to turbine scroll exhaust outlet.
The formula 1 turbocharger waste-gate cannot be build into the turbine scroll because the design aim is not that of controlling the compressor boost but to bypass exhaust gases away from the turbine scroll relieving turbine scroll pressure so as the compressor can get to and maintain maximum boost by electric supercharging.

This isn't correct. Renault, at least, have run a wastegate mounted on top of the turbine house.

[henry]

The formula 1 turbocharger is not a normal turbocharger.
The normal turbocharger will in most cases have the waste-gate build into the turbine scroll, the design aim of which is to control boost by relieving exhaust gases pressure inside the turbine scroll, in doing so it relieves pressure inside the turbine scroll by internally bypassing exhaust gases straight to turbine scroll exhaust outlet.
The formula 1 turbocharger waste-gate cannot be build into the turbine scroll because the design aim is not that of controlling the compressor boost but to bypass exhaust gases away from the turbine scroll relieving turbine scroll pressure so as the compressor can get to and maintain maximum boost by electric supercharging.

This isn't correct. Renault, at least, have run a wastegate mounted on top of the turbine house.

As do Ferrari,



And Honda,



So I think it’s pretty clear that the wastegates are positioned to vent the turbine scroll in such a way as to continue to harvest some energy from the exhaust whilst reducing back pressure.

[ian_s]

(braking against throttle to harvest because only when brake pedal is used can the K go into harvest)

This is wrong. there is nothing in the regulations that say it can only generate when braking.

[saviour stivala]

No the waste-gate/s are not positioned to vent exhaust turbine scroll. The waste-gates are positioned to bypass exhaust turbine scroll.
None of the four formula one engines uses a build-into-the-exhaust turbine scroll housing waste-gate/s. build- into-the-exhaust turbine scroll housing waste-gate can only relieve exhaust turbine scroll pressure to control compressor boost and not bypass the exhaust turbine scroll to eliminate back pressure so as the compressor can be operated in electric supercharging mode. A waste-gate positioned on top of the exhaust turbine housing doesn’t mean it is build into said housing.

[saviour stivala]

(braking against throttle to harvest because only when brake pedal is used can the K go into harvest)

This is wrong. there is nothing in the regulations that say it can only generate when braking.

The MGU-K (where the ‘K’ stands for kinetic) converts kinetic energy under braking into electricity (rather than it escaping as heat).