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      08-10-2008, 04:01 AM   #1
Neema
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Quick M5/M6 "P-Mode" question....

We all know about the Power button in the M5 and M6 that can engage either the full 507hp when activated, or just limit the engine to 400hp when not activated.

So my question is, what is actually happening technologically and mechanically that is able to limit so much power in a naturally aspirated engine. How do you electronically control horse power, especially in a naturally aspirated car that doesn't give you options like boost/turbos to play with? I would understand it if we had such a button in the 335 because I could see where the power was coming from. Things like limiting boost, fuel, and air.....but what about in an N/A car?

What is the engine/car doing to limit itself down to 400hp and then make a whopping leap to 500hp? We're talking about an extra 100hp. So what is it? VANOS? Limiting fuel/air ratios? Or what?

Does this question make sense?
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      08-10-2008, 04:44 AM   #2
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I'm not sure and this could be totally out of left field but I thought it had to do with actually shutting off cylinders?
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      08-10-2008, 04:49 AM   #3
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Quote:
Originally Posted by ironic View Post
I'm not sure and this could be totally out of left field but I thought it had to do with actually shutting off cylinders?
Could very very well be the reason, I know that Mercedes has been doing that with their V-12 engines for quite some time now. I've just never heard any talk of such a thing in BMW's, and for leap as big as 100hp + or - ...... is that thing shutting down like 4 cylinders or what?!
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      08-10-2008, 04:53 AM   #4
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I thought it was some type of cylinder deactivation as well...not really sure though.
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      08-10-2008, 05:00 AM   #5
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from m5board.com : http://www.m5board.com/vbulletin/e60...ost434807.html


The mechanics of the P400 button aren't that hard to grasp. Remember that
you have an electronic throttle. All they have to do is NOT open the throttles
fully and/or de-optimize the camshaft positions. BMW already did this with
the '01/'02 M Roadster vs. the '01 M3. (315hp vs 333 by cam positions/etc)
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      08-10-2008, 05:09 AM   #6
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Quote:
Originally Posted by Big Windy View Post
from m5board.com : http://www.m5board.com/vbulletin/e60...ost434807.html


The mechanics of the P400 button aren't that hard to grasp. Remember that
you have an electronic throttle. All they have to do is NOT open the throttles
fully and/or de-optimize the camshaft positions. BMW already did this with
the '01/'02 M Roadster vs. the '01 M3. (315hp vs 333 by cam positions/etc)
how the hell could I have forgotten about THROTTLE CONTROL?! I see now
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      08-13-2008, 12:22 PM   #7
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wow! interesting! Thanks! +1 to my list of BMW knowledge
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