ADias

You may be correct and I may be wrong. It may strictly be throttle mapping but I maintain that it is not just a different bias point; the profile is more progressive, and it cannot be reproduced just by pressing harder on a non SC equipped car. No question though that a PDK car needs SC, as it also changes shift points.

bhvrdr

I do see where you're coming from and yeah that change can be done with throttle mapping. And that's because throttle mapping is not just a straight line. Throttle mapping can take on any curve that the factory wants to reproduce.

And you're absolutely right it's not just one of those why don't you just push the pedal harder kind of things. This is one of the reasons there are usually endless debates about whether or not the sprint booster is effective at all.

While it is true that the sprint booster does nothing to actually increase the engines power output almost all people who try it universally say that the car feels peppier and that it is not something that can be reproduced by just slamming down the pedal a little bit harder on a car without a sprint booster. That's because they are absolutely correct in the sense that it is almost impossible to precisely mimic a different throttle map with your foot.

In some cases the throttle Maps can be so different that literally the only place where they are identical in the RPM range is sitting at idle at 0% TP or sitting over 80% TP which would induce 100% TB opening. This is basically wide open throttle. Anywhere in between there in the maps could be very different.

mike

Frederic944

bhvrdr

what's torque shaping and anti jerk function?

Mike

Frederic944

bhvrdr

Are you suggesting this is a function of the Bosch motronic 7.8 or Siemens sdi3 that we are discussing?

Frederic944

bhvrdr

where do you find this documented as a function of the motronic 7.8 or sdi3?

Mike

Frederic944

bhvrdr

Its an interesting discussion because i've been on the consumer and enthusiast end of Bosch Motronic systems and others since the early 2000s (as opposed to an engineering perspective) and have enjoyed venturing into calibrations of these systems as well as extensive datalogging. There are a few different really good references I liked...

https://www.barnesandnoble.com/p/bos...SABEgK0YfD_BwE


Its my understanding the overall timing is calculated based on the following:
A twin three-dimensional table lookup that corrects the ignition timing angle for intake air temperature and is also a function of engine load, and engine speed. (and batter voltage IIRC)
+
A three-dimensional lookup that corrects for engine coolant temperature and is also a function of load.
+
The main timing lookup table which is a function of engine speed and engine load. On variable valve timing or variable cam lift engines this can be two or four tables that are representative of the state of the switchover. These timing lookups are the ones that are changed in performance chips. Bosch refers to these lookups as the base RON lookup tables.
+
A three dimensional lookup that corrects for air-fuel ratio and is also a function of engine speed.
+
Ignition timing adaptation values (what we Audi guys used to fool around with using lemmiwinks)
+
Cylinder selective timing retardation. (IKC also known as timing pull/timing retard)
=
Ignition advance angle (*BTDC)




Its pretty easy to test the hypothesis we are discussing with simple datalogging of parameters like eng tq, MAF, ign tmg both in and out of sport mode. I dont see any evidence these parameters would change at WOT based on the sport mode. Otherwise Porsche would literally have to publish the power differences in their engines in and out of sport mode as they do on some models that really do have a sport button that impacts max power (ie, vehicles with overboost buttons that advertise the hp this adds or the M5 "M button" that advertises the hp it adds).

https://www.pistonheads.com/gassing/...f=181&t=748806

Its interesting the points Adias and you bring up though (perhaps with your engineering background?)



I think you each bring up different points.



Adias is bringing up changes in power output related to throttle mapping (ie, when you are at a 30% TP in regular mode you get 20% TB opening and lets say at 30% TP in sport mode you get 30% TB opening). So at a given part-throttle application of lets say that 30% throttle position, technically the car is slower. That’s not because of a change in engine mapping, but because of the throttle mapping. The engine will still put out the same power at WOT or at each increment of TB opening. Its just the TP relative to the TB opening is vastly different.



You bring up different points though discussing “anti jerk” functions. To me, wouldn’t this be more of a function of PSM and even PASM? As an example, if I disable PSM I can jerk this crap out of this car. You can bounce tires and break axles like no other whether you are in sport mode or not with PSM disabled. But enabling sport mode does enter you into a sport PSM mode that allows more wheel spin so perhaps indirectly a person may be able to achieve faster 0-60, 0-XX times due to PSM doing things like timing/fuel cuts based on ABS sensor input and other inputs. So this may be another “indirect” way you are getting different perception of power from the car. But again, if you had good traction, the engine is putting out the same power at WOT whether in sport or non sport mode or with PSM full enabled, in sport mode, or full disabled.



Interesting discussion.



Mike

Frederic944

Mike,

What you mention above is definitely correct and describe how engine controllers have been calculating Spark Advance for the past 20-25 years, and to add to your list, there's also correction based on time after start, altitude, EGR, position of the active manifold, swirl flap..etc
OEM starts to move away from MAP, because with variable CAM timing,you would have hundreds of MAP just base Spark, so they either move to Physic Based model, identifying the combustion at every loop time: TDC and characterize by equations modelizing the amount of fresh air in the cylinder.

Also, i don't if you realize but now with the complexity of powertrain, controllers have between 50,000 and 100,000 parameters you need to calibrate.


And to go back to the base discussion about SC and different mapping, you are right, it doesn't change the max output of your engine but will modify how the torque is delivered and it's where some of the functions I mentioned above: Torque Shaping and Anti Jerk control, without these functions, your vehicle would really not pleasant to drive, what they do is they modify the torque delivery, meaning between what the Driver is requesting through its pedal and how this Torque Request is delivered to he flywheel. Remember how cars with carburetor were driving? jerks, oscillation, shock etc...

BillNye

This is why I get annoyed when people take a brand new car and flush tens of thousands of man hours spent by the OE calibrators down the toilet with a $600 flash tune.

ADias

So... it appears that what I was told by Porsche people is correct. I never claimed power/torque gains, just a different engine controls that is far more dynamic and responsive than the 'Normal' setting.

Thanks for confirming this!

bhvrdr

lol oh brother. You stated that there is more aggressive ECU mapping. I would still state that there is no evidence of this outside of throttle mapping and the evidence is to the contrary from Porsche themselves.

everything you've described in porch has described can be attributed to throttle mapping

ADias

My definition of throttle mapping is the mathematical relationship between the throttle pedal angle and the throttle plate angle. Sport Chrono does that and more. The secrete sauce is the 'more' it does beyond mechanical angle relationships.

If, what you call throttle mapping goes beyond mechanical angle relationships and includes possibly cam control and other engine parameters, then we agree - it is what you call throttle mapping.

And for the record... my experience is with 997.2s not 997.1s SCs.