Mercedes Power Unit Hardware & Software

[stevesingo]

I can see MHPE developing contingency mapping in the case of VLIM failure. In that they will develop a map which is dependant on VLIM position so in the case of failure the ECU will adjust fuel and ignition compensations to ensure safe running.

[Big Tea]

I can see MHPE developing contingency mapping in the case of VLIM failure. In that they will develop a map which is dependant on VLIM position so in the case of failure the ECU will adjust fuel and ignition compensations to ensure safe running.

Would they not already have a 'fail safe' option in the software?
Maybe not best performance, but capable of continuing the race.

[henry]

I can see MHPE developing contingency mapping in the case of VLIM failure. In that they will develop a map which is dependant on VLIM position so in the case of failure the ECU will adjust fuel and ignition compensations to ensure safe running.

Would they not already have a 'fail safe' option in the software?
Maybe not best performance, but capable of continuing the race.

Given the reported interventions by Brixton and the pit-wall it would appear that they did not have a fail-safe, or if they did it wasn’t safe enough.

I’m guessing that they run with fixed maps for boost, injection quantity and timing, and spark timing. These values are then tweaked by evaluation of actual operating conditions based on sensor readings, lambda, detonation, exhaust temp etc. My guess is that there are boundaries as to how much the tweaking system can change the mapping and in this case they couldn’t change them enough.

[Big Tea]

I can see MHPE developing contingency mapping in the case of VLIM failure. In that they will develop a map which is dependant on VLIM position so in the case of failure the ECU will adjust fuel and ignition compensations to ensure safe running.

Would they not already have a 'fail safe' option in the software?
Maybe not best performance, but capable of continuing the race.

Given the reported interventions by Brixton and the pit-wall it would appear that they did not have a fail-safe, or if they did it wasn’t safe enough.

I’m guessing that they run with fixed maps for boost, injection quantity and timing, and spark timing. These values are then tweaked by evaluation of actual operating conditions based on sensor readings, lambda, detonation, exhaust temp etc. My guess is that there are boundaries as to how much the tweaking system can change the mapping and in this case they couldn’t change them enough.

I follow, but assumed there would have been a 'keep it in one piece' mode that switched in automatically if things went outside the bounds of healthy. Like a limp home mode on a road car.

Keeping in mind all the 'suck it and see' options had to be entered by the driver and then monitored.
Would have been quite a juggling act.

[saviour stivala]

“VLIM?”. On lap 28 Mercedes PU engineers both at pit garage and back at base in UK monitoring telemetry reported that a failure was imminent due to an exhaust issue that had led to high temperatures.

[63l8qrrfy6]

“VLIM?”. On lap 28 Mercedes PU engineers both at pit garage and back at base in UK monitoring telemetry reported that a failure was imminent due to an exhaust issue that had led to high temperatures.

And what exhaust issues would cause high EGT ?

[saviour stivala]

"Well our exhaust is just about to fail, and we're overshooting all temperature limits".

[Webber2011]

For dumbos like me, could someone explain how the VLIM works, or point me to the proper thread please ?

I have a basic understanding, but always like to learn more.

Thanks

[63l8qrrfy6]

"Well our exhaust is just about to fail, and we're overshooting all temperature limits".

Right so high EGT causing the exhaust to fail. What is causing the high EGT?
That's what was being discussed but again you can't be bothered to read previous posts.

[subcritical71]

For dumbos like me, could someone explain how the VLIM works, or point me to the proper thread please ?

I have a basic understanding, but always like to learn more.

Thanks

Not a thread, but here’s a basic video from YouTube:

[saviour stivala]

"Well our exhaust is just about to fail, and we're overshooting all temperature limits".

Right so high EGT causing the exhaust to fail. What is causing the high EGT?
That's what was being discussed but again you can't be bothered to read previous posts.

Who can tell what was causing Mercedes high (1000-980 degree) EGT except their engineers in front of their flowing telemetry?. And speaking of Mercedes regarding 1000-980 degree EGT as high, I remember a 2003 BMW 3.0L V10 running at 19250 RPM registering a EGT of 1750 degree and there was no way they could use their Inconel exhaust headers for a second race.

[hollus]

And yet, we can speculate and narrow down the possibilities, which is perfectly fine (and fun) as long as the speculation is grounded in sources, physics and common sense.

[63l8qrrfy6]

"Well our exhaust is just about to fail, and we're overshooting all temperature limits".

Right so high EGT causing the exhaust to fail. What is causing the high EGT?
That's what was being discussed but again you can't be bothered to read previous posts.

Who can tell what was causing Mercedes high (1000-980 degree) EGT except their engineers in front of their flowing telemetry?. And speaking of Mercedes regarding 1000-980 degree EGT as high, I remember a 2003 BMW 3.0L V10 running at 19250 RPM registering a EGT of 1750 degree and there was no way they could use their Inconel exhaust headers for a second race.

There aren't many reasons for EGT to shoot up, one such reason has already been discussed.

Once again your post adds nothing to the conversation, the whole point is to discuss potential failure modes. There are a few good engineers on this forum that can construct a good hypothesis, unfortunately you are not one of them.

[saviour stivala]

Right so high EGT causing the exhaust to fail. What is causing the high EGT?
That's what was being discussed but again you can't be bothered to read previous posts.

Who can tell what was causing Mercedes high (1000-980 degree) EGT except their engineers in front of their flowing telemetry?. And speaking of Mercedes regarding 1000-980 degree EGT as high, I remember a 2003 BMW 3.0L V10 running at 19250 RPM registering a EGT of 1750 degree and there was no way they could use their Inconel exhaust headers for a second race.

There aren't many reasons for EGT to shoot up, one such reason has already been discussed.

Once again your post adds nothing to the conversation, the whole point is to discuss potential failure modes. There are a few good engineers on this forum that can construct a good hypothesis, unfortunately you are not one of them.

Correct, I do not pretend to be.

[ringo]

egt will increase with an MGUH or Turbine flaw.
I suppose that the increased temperatures can also be related to some other failure as well, maybe air or fuel system; some kind of sensor or the VLIM as said before; it can be a host of things.