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It stays the same. As far as I know the only difference between P400 and P500 is that the throttle butterflies (I think) are only open at 90% intsead of 100% for P500.
 

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SoulBladeZA said:
It stays the same. As far as I know the only difference between P400 and P500 is that the throttle butterflies (I think) are only open at 90% intsead of 100% for P500.
but i think you can still rev to red line in P400 mode, and if throttle butterflies is the only difference, you should still be getting 507bhp at 7725rpm. on that basis, i think there's more to P400 than throttle butterfly.
 

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P400 is supposedly only a restriction to the throttle butterfly to open to 90% at full throttle. If this is true, then I believe max torque should be down also, since max torque would be achieved with 100% throttle opening.
 

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450Nm.
 

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There must be something else: I guarantee this difference ; ) While You are driving for example around 5000 rpm with P400 and You push this button, car jumps little bit forward and sounds changes.

The torque is hugely different, even it redlines in both modes, but in P400 it is slower and feels little bit soulless. When accelerating from lower rpm's, You feel and hear the diiference on acceleration, so there is definately something more on it !

I have only 700 km's on my beast but I always use P500 and DSC off if it is dry with fastest setting on SMG. It is nice to give some rubber once in a while : ) and also when You have experienced +500 You can't live without it! : )
 

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if it is anything like the e39 m5, the "power" button changes the "throttle bodies" step vs. accellerator resistance ratio.

in english this means that in p400 if you press the accellerator x-degrees the throttle bodies open y degrees where x-max (wot) is still 90% of y-max.

in p500 mode x-max (wot) is y-max.

thus if you are at partial throttle and you push the p500 mode the throttle bodies actually open a bit more which accounts for the "jump" in power (accelleration).

said that, in p400 the tq should change a bit (but not much since torque likes long and narrow intake and reducing the flow by 10% should not show much) but hp at higher rpms should be significantly down...

just a theory ;)

alex
few cars
 

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Pretty sure AJ hit the nail on the head... enter my gripe..

In P400 mode, it should alter the fuel/spark/valve timing to increase the torque a bit more. Maybe it does and that is all the V10 has... but I doubt it. Seems like they could play with valve timing to get a bit more out of it for around town.
 

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Would you guys ever drive around in P400? I think I would be in P500 all the time, except maybe bumper-bumper traffic if P400 would provide a tiny fuel economy benefit. But maybe I am wrong and if I lived with the car I would see P400= putting around and P500= when I want to be more aggressive...
 

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Well, I look at it this way. Why have it in P500 when I am sitting there just fighting my way into work in bumper to bumper traffic, or just about any time I am not exercising the engine. Its not like 400hp is something to sneeze at!
 

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All of the information posted thus far indicates that P400 has the single function of limiting how far the throttle may open, and thus it has the same effect as a block of wood placed under the accelerator peddle with the same consequences on torque, power and fuel economy.

Tom
 

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and to think the good ole "bunched up carpet under the loud pedal" now has a whole new meaning :D :typing:

alex
few cars
 

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bernhtp said:
All of the information posted thus far indicates that P400 has the single function of limiting how far the throttle may open, and thus it has the same effect as a block of wood placed under the accelerator peddle with the same consequences on torque, power and fuel economy.

Tom
I don't think You are right on this one. If for example, You would have that piece of wood under the accelerator pedal the engine would not reach that high rpm's anymore.

But on P400 mode engine still rev's up the same it does with P500. SO I am still on previous opinions that this system does something else adjusting different systems , to be able to accomplish it's task to produce different power readings with same rpm's.

And trust me, the feeling of the torque while accelerating is so much difference in P400 that I almost hate to use it! : )
 

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BradM5 said:
I don't think You are right on this one. If for example, You would have that piece of wood under the accelerator pedal the engine would not reach that high rpm's anymore.
Engines easily reach their full RPMs at 75% throttle. More throttle means more torque at any engine speed, especially at higher RPMs where the extra fuel/air can be more effectively used.

Tom
 

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Here's an excerpt from BMW's press release.

"By pressing the power button on the selector lever cover, the driver can activate a sportier program with full performance characteristics. The activation of this program results in a more progressive response of the throttle butterfly to the accelerator pedal with the dynamic transient functions of the electronic engine management system switching over to a more instantaneous response."

Sounds like the switch from P400 to P500 involves "...switching over to a more instantaneous response." as well as changing the throttle butterfly limit. Perhaps the solenoid that controls the butterfly is somewhat delayed or damped as well as limited in P400 so the engine response isn't quite as immediate.
 

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This confirms my belief that P500 changes acclerator pedal to throttle mapping (like "Sport" does on other M cars) but also sets a higher limit for the throttle to achieve full power.

Tom
 

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agreed an both points -

redline can be achieved at partial throttle (maybe not in 6th and/or 7th gear though- it is very hp/gear specific)

and yes, i think sports button causes bigger deflection of butterflies in relation to gas pedal thus achieving two goals- crispier response and 100% opening at wot
 

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Phew!! This thread has certainly cured my insomnia... ouich

I have a button on my steering wheel with an 'M' on it. I press it, my car goes faster. What else matters?! :1:
 
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