Does anyone know exactly how the over boost works on the F56 MINI's? I know it adds a little more boost but how exactly? Is it by throttle position or RPM. I doubt you have to rev it all the way to 6000 RPM to get the over boost.

 

Just speculation, however I believe it is a mechanical function, in conjunction with a programmed or tuned function by the ecu. I have been using an electronic boost gauge and notice that I see the highest boost levels when pushing the pedal to the floor, pressing the "kick down button". It requires building to a high rpm to build the boost levels required for the 10-15 seconds of over boost.

Basically it works by kicking the car down a gear and flooring it.

 

I haven't been able to fully decipher it yet, but based on the data-logging I've done it appears to be "delta time load request" based. Basically, if you roll onto the accelerator pedal slowly to the floor, you'll get normal boost. If you lift your foot and SMASH the pedal to the floor, it appears most of the time you'll get over-boost. This was exactly the case with the R56, FWIW. It appears to function at lower to mid RPM's, as the ECU will pull boost at higher RPM and thus won't make any more top-end power in over-boost mode. What that RPM threshold is I haven't nailed down yet.


-->rob.james.arias: I presume you have an auto trans? Manual trans cars don't have the kick-down position pedal.




I really wish the OEM's would stop this style of "emotional" calibration. When my foot is on the floor, I want maximum torque, not an interpreted value based on how quickly I push the pedal.

 

Sounds like it maybe one of those fuzzy logic things and it tries to sense when you would like the extra torque. I have noticed when aggressively trying to get through traffic I get a little extra punch. Thanks for your insight on the over boost on the MINI.

 

You are correct I have an auto. One other thing I noticed while data-logging, that stumped me, is when the value "pedal position" is at a maximum of 98%, "throttle position" is never more than 88.6%. It seems odd that it doesn't open more than that. My last non MINI vehicle would open to 96%. Seems like some airflow may be left on the table. Less air=less boost in long round about way?

 

I've never [and that's a strong word] seen an OBDII sensor read throttle position at either 0% or 100%, it just doesn't happen. On an aftermarket ECU, sure, because you can dictate the endpoint values as you see fit.

Given that a typical butterfly throttle body doesn't flow any more air after about 50% angle* (*roughly, it depends), there's no need to fuss much over a few percent on the datalog. Anything over 80% is usually considered WOT.


In any case, we can't be sure what the OBDII "throttle" is showing, given the engine uses both the thottle body and Valvetronic servo to target MAP, valve head pressure delta, and intake pumping loss calculations.

 

Fair enough, I am new to this platform and thought it was interesting.

 

I did some more driving. I was about convinced that the over boost was just a matter of using the last 20% of the throttle pedal but I still think the speed that you press the throttle also has an effect on activating over boost. I think I am getting a feel for it. I just went over the 1000 mile mark so I am still learning.

 

Although tonight I am going through the middle of a hurricane, I'm going to try to nail this down as soon as I get back home and to my car (in the garage). I'm close to 10k, and am really starting to learn my 2017 MCS 6-speed. I've definitely felt and heard a sensation that's seemingly the turbo spooling a bit, let's say third gear 35 mph, blowing off and spooling up again for all good hell. I've whipped a nice overtake or two on the highway and thought I was going a little quicker that I expected, but I wish I had more control over this overboost.