Renault Power Unit Hardware & Software

[turbof1]

If I'm correct, a wastegate is only a fallback system when the mgu-h fails. So could be rather an issue with the mgu-h if knocking is at the root of the issue.

I doubt that though. Does anyone have a list of the tokens Renault used?

[ojlopez]

If I'm correct, a wastegate is only a fallback system when the mgu-h fails. So could be rather an issue with the mgu-h if knocking is at the root of the issue.

Yes, according to Renault's website "On the Renault Energy F1 power unit, the turbo rotation speed is primarily controlled by the MGU-H, however a wastegate is needed to keep full control in any circumstance (quick transient or MGU-H deactivation)"

[Wayne DR]

If I'm correct, a wastegate is only a fallback system when the mgu-h fails. So could be rather an issue with the mgu-h if knocking is at the root of the issue.

I doubt that though. Does anyone have a list of the tokens Renault used?

Ahhh, now I see the light! At the boost pressures they are possibly running, Renault could be experiencing compression ignition/detonation/knocking. Continued high levels of detonation would certainly explain the significant ICE damage (and matched Ricciardo's description of what happened at the end of Bahrain - pressed the loud pedal and heard a series of misfires/detonations).

So the root cause could be as simple as fuel composition/quality (RON/MON too low), spark advance mapping (that 1 degree too much) or even a fuel mapping (that little bit too rich) related issue...

[trinidefender]

If I'm correct, a wastegate is only a fallback system when the mgu-h fails. So could be rather an issue with the mgu-h if knocking is at the root of the issue.

I doubt that though. Does anyone have a list of the tokens Renault used?

Ahhh, now I see the light! At the boost pressures they are possibly running, Renault could be experiencing compression ignition/detonation/knocking. Continued high levels of detonation would certainly explain the significant ICE damage (and matched Ricciardo's description of what happened at the end of Bahrain - pressed the loud pedal and heard a series of misfires/detonations).

So the root cause could be as simple as fuel composition/quality (RON/MON too low), spark advance mapping (that 1 degree too much) or even a fuel mapping (that little bit too rich) related issue...

Last season the Renault engine developed a reputation for being (or at least appearing to be) very sensitive to ambient air temps. It seems that as a result of this teams had to run larger intercoolers than anticipated. Hot temperatures plus high altitudes will be the worst combination as the higher altitude means that the turbocharger has more compressing to do. More compressing = more heat in the intake air needing yet again a larger intercooler which, ironically will be less effective as a result of the hot, lower density ambient air at the track.

[toraabe]

If I'm correct, a wastegate is only a fallback system when the mgu-h fails. So could be rather an issue with the mgu-h if knocking is at the root of the issue.

I doubt that though. Does anyone have a list of the tokens Renault used?

Ahhh, now I see the light! At the boost pressures they are possibly running, Renault could be experiencing compression ignition/detonation/knocking. Continued high levels of detonation would certainly explain the significant ICE damage (and matched Ricciardo's description of what happened at the end of Bahrain - pressed the loud pedal and heard a series of misfires/detonations).

So the root cause could be as simple as fuel composition/quality (RON/MON too low), spark advance mapping (that 1 degree too much) or even a fuel mapping (that little bit too rich) related issue...

Remember that running too high compression also is a common issue to knocking on turbo engines as Renault described " that they have found that their piston has some design flaws. Remember last year they could never run full power due to knocking...

[piast9]

Ahhh, now I see the light! At the boost pressures they are possibly running, Renault could be experiencing compression ignition/detonation/knocking. (cut)

I doubt that it is that simple. There are sensors that detect knocking. If they are used in the F1 engine then the ECU may alter the spark advance to prevent piston damage. I know that Renault is not doing well right now but they are not dumb people.

[toraabe]

Ahhh, now I see the light! At the boost pressures they are possibly running, Renault could be experiencing compression ignition/detonation/knocking. (cut)

I doubt that it is that simple. There are sensors that detect knocking. If they are used in the F1 engine then the ECU may alter the spark advance to prevent piston damage. I know that Renault is not doing well right now but they are not dumb people.

Renault have to eliminate the current gap and they will.
Not only for RB and Renault, but also for F1.

[FW17]

Renault - Red Bull Relationship has now become like a Peugeot - McLaren relationship

[Wayne DR]

I doubt that it is that simple. There are sensors that detect knocking. If they are used in the F1 engine then the ECU may alter the spark advance to prevent piston damage. I know that Renault is not doing well right now but they are not dumb people.

With the current level of external pressure being applied, I am sure Renault are not looking to leave any ICE capacity on the table. They are relying on their PUs to go into "Safe Mode" with reduced power, only when a sensor fails or ICE parameters go outside component operating limits or design limits.

From my experience, generic knock sensors (used in road cars) are conservative (susceptible to false readings from gear changes, shock loads on the power train, etc). I can't remember seeing a race engine that uses this technology. I have seen fixed ICE maps (for say fuelling and spark, calculated continuously using various sensor inputs - load, intake air temperature, coolant temperature, RPM, Manifold Pressure, etc) that are setup on engine dynos at the factory, and only varied slightly at the track to suit ambient conditions (during installation laps).

I'm not saying Renault Tech's are dumb, track conditions are very different to what can be created on an engine dyno. Internal stresses at maximum load limit ICE life on a dyno, making it impossible to examine every possible scenario over the whole RPM range and every condition. Renault have possibly been unlucky, and not been unable to recreate failure conditions in the factory (due to some discrepancy between their modelling/equipment and the track conditions).

[langwadt]

Ahhh, now I see the light! At the boost pressures they are possibly running, Renault could be experiencing compression ignition/detonation/knocking. (cut)

I doubt that it is that simple. There are sensors that detect knocking. If they are used in the F1 engine then the ECU may alter the spark advance to prevent piston damage. I know that Renault is not doing well right now but they are not dumb people.

I'm not sure knock sensors would work very well in such a high reving noisy engine

[Facts Only]

Ahhh, now I see the light! At the boost pressures they are possibly running, Renault could be experiencing compression ignition/detonation/knocking. (cut)

I doubt that it is that simple. There are sensors that detect knocking. If they are used in the F1 engine then the ECU may alter the spark advance to prevent piston damage. I know that Renault is not doing well right now but they are not dumb people.

I'm not sure knock sensors would work very well in such a high reving noisy engine

What's not been mentioned here is a phenomenum called "Super Knock", simplest explanation I could find below:

High boost and direct injection are the main tendency of gasoline engine technology. However, pre-ignition/super-knock tends to occur at low-speed high-load conditions, which is the main obstacle for improving power density and fuel economy.

Plenty more on google though.

Interesting abstract:
http://jer.sagepub.com/content/early/20 ... 7411431890

With the current engines being more fuel limted above 10500rpm the engine makers are pushing high boost conditions at lower rpms which cause the above super knock, the main problem for the engine makers is that to get the best power and efficiency you need to run as close as possible to 'super-knock' conditions.
I assume to try to gain more power this year Renault have had to try to work the engine closer to super-knock conditions but its incerdibly damaging to the engine if Super-Knock does occur and also very hard to predict before it happens.
As well, super-knock would put a massive load into the piston and its mounting pins, which is the failure mode that Renault seem to be claiming.

[mrluke]

Im not sure how the above is really any different from normal "knock"

The problem isn't just that the Renault engine has knock problems and they dont know how to fix it, its that to get the maximum power from the available fuel they need to run high boost and lean meaning that their available power is limited by knock. Renault are under lots of pressure to get more power so they are pushing this knock limit as much as they can.

There's clearly something that Mercedes and now Ferrari are doing to get around this limit that Renault have hit, Renault just aren't sure what that is yet.

[Blackout]

Maybe because the Renault, unlike the Merc and even the Ferrari, has a compresor that sits just in front of the turbine and (very long) charge air ducts that almost rub the exhaust pipes...
That is a part of a complex problem.

[Facts Only]

Im not sure how the above is really any different from normal "knock"

From my experince with this area a few years ago and further reading I understand it as the following.

There are various different types of knock, its a spectrum.

Pre-ignition may lead to super-knock, heavy knock, slight knock, and non-knock. Compared with conventional knock, knock intensity of super-knock is much higher and the maximum amplitude of pressure rise at start of knock is more than one order of magnitude higher.

Super knock is far more destructive than other variations of knock. The way the current F1 engines are running High Boost, High Cylinder pressures and lean running can lead to super knock as soon as there is pre-ignition which can detroy parts of the engine almost instantly. If you can detect knock then various parametres can be changed to stop it, but with Super Knock once its been detected the damage is already done. It also seems that it often propogates from hot-spots on the piston which tallies with Renaults need for new piston designs and their failures in the piston pins as well as the supposed sensitivity of the engine to air temps.

I have also heard claims that Renaults engine is 20bhp down in the cars compared to the dyno, perhaps this is due to the presence of super knock in real world conditions and them having to run further from the optimum operating window to avoid it. The complex nature of the subject would also give some reason as to why Renault are quoting such long lead times for a fix.

[R_Redding]

I've no idea where stories of "knocking" have appeared from.

I'd be very surprised if they have a problem in relation to that.


Bosch and Magnetti-Marelli have been using Ion current detection and DSPs (Digital Signal Processing chips) to map the exact conditions in each spark event for some time now. I know Ferrari were using it in the early noughties when Siemens brought out 32bit micros under the Infineon umbrella.

Also..The standard auto acoustic Piezo knock sensors work at around 25 to 50hz .. which is okay on a family car but no where near fast enough for a highly strung modern racing engine where knock can be in the 11-16khz range. By the time a Piezo sensor detects knocking , an F1 engine would be toast.

I have been wondering if their "block" has been lightened too much and is flexing , causing the bore to grab a piston ring.

Rob