Stock boost

[Keanu111]

What is the stock boost in a 1M? Apparently my boost gauge is saying 8.5 psi? Thanks

[bdaddylo]

Which boost gauge are you using? I believe overboost is 14.5 psi.

[EINSER M]

stock boost 11.5 psi
overboost 14.5 psi

[Keanu111]

Im using the p3 guage..

[///M1]

Originally Posted by EINSER M

stock boost 11.5 psi
overboost 14.5 psi

+1 (give or take a decimal place ). Verified physically (through P3 Boost gauge version 1) and electronically through ECU.

BTW, haven't really tried this as I don't push my car to the max when cold, but I think overboost in tapered down while engine is cold. (IIRC there was a dyno by a member wondering why he was down on boost but the car had been cold when they did the dyno runs).

[Waldo23]

Factory States:
Normalbetrieb: ca. 1.75bar
Overboost: ca. 1.95bar

(Subtract atmosphere pressure from this)

[Dackelone]

Originally Posted by Waldo23

Factory States:
Normalbetrieb: ca. 1.75bar
Overboost: ca. 1.95bar

(Subtract atmosphere pressure from this)

So... for the non metrics out there...


1 Bar atmosphere pressure = 14.50 PSI.

Normal boost = 10.875 psi
Over boost = 13.775 psi

[bdaddylo]

While testing my record mode on my P3 two weeks ago, I had a peak boost of 15.2. I'm not sure if the P3 gauge was faulty or there was a blip in my ECU that allowed that much boost. I haven't tried to replicate it, but I probably should.

[Artemis]

Originally Posted by Dackelone

So... for the non metrics out there...
1 Bar atmosphere pressure = 14.50 PSI.
Normal boost = 10.875 psi
Over boost = 13.775 psi

Values (http://www.onlineconversion.com/pressure.htm):

• 0.8 bar = 11.603019041 pound/square inch
• 1.0 bar = 14.503773801 pound/square inch

1M vs. 135i:

• 1M stock boost pressure = 0.8 bar (0.8 x 14.5 = 11.6psi normal boost).
• 1M overboost = 1.0 bar (1.0 x 14.5 = 14.5psi)
  (http://www.1addicts.com/forums/showp...4&postcount=37)
  (http://www.bmwblog.com/2011/05/13/bmw-1m-full-specs/)
  if 1M overboost = 0.95 bar, then 0.95 x 14.5 = 13.775psi (as Dackel pointed out)
  if 1M overboost = 0.90 bar, then 0.90 x 14.5 = 13.05psi
• 135i stock boost pressure = 0.6 bar (0.6 x 14.5 = 8.7psi normal boost)
  (http://www.1addicts.com/forums/showp...5&postcount=29)
  (http://www.cars.com/bmw/1-series-m/2...s/?revid=57551)

More info:
http://www.1addicts.com/forums/showp...4&postcount=37 (from http://www.1addicts.com/forums/showthread.php?t=558700)
http://www.1addicts.com/forums/showp...4&postcount=18 (reference to 2007 Engine Management)

1M "Overboost", what's in a name ? (info pointed out by a Belgian tuner - Dec 2011) (for those who do not understand French and want to catch the drift of the comment, copy the text in http://translate.google.com/#fr|en| ):

"Un overboost, c'est un dépassement temporaire de la pression de turbo pendant une courte durée. Ceci existe sur presque tous les véhicules turbo-compressés récent (depuis 2005). Pratiquement, lorsque vous êtes à vitesse stabilisée et que vous appuyez sur la pédale à 100%, au lieu de donner 0.8 bar de pression, pendant un court instant le turbo donnera 0.9 ou 0.95 bar de pression. Ce qui apportera plus de couple. Attention, ceci est fait sur base d'un timer, du coup, vous apercevrez la non répétabilité de cette fonction si vous appuyez et puis relâchez la pédale d’accélérateur plusieurs fois. Dans le cas de la BMW 1M, c'est différent. On parle dans les articles d'overboost, mais c'est plus complexe que cela, c'est en fait une autre map de boost qui intervient quand le bouton M est enclenché. Voici pourquoi on a 50Nm supplémentaires, la faisant passer à 500Nm théoriques.
Pourquoi 500Nm théoriques ? Car d'une voiture à l'autre, les wastegates sont réglées légèrement différemment, ce qui fait que certaines voitures ont plus de puissance / couple que d'autres. De plus, les Allemands utilisent pour la calibration la norme ISO qui est plus stricte que la norme DIN. Dès lors si vous avez 450Nm en norme ISO vous pouvez en avoir 465 en norme DIN.
Après préparation, nous supprimons l'overboost, sinon nous aurions trop de couple ce qui serait mauvais pour l'embrayage mais aussi les turbos (température trop élevée).
Un overshoot, c'est un dépassement de la consigne du boost au moment du spool (principalement), je m'explique. Lorsque vous appuyez à 2000tr/min avec votre 1M, la consigne du boost à atteindre est de 0.8 bar, malheureusement, à ce régime, il n'y a pas encore assez de gaz d'échappement pour donner cette pression (les turbos étant, pour rappel, entraînés par les gaz d'échappement), l'électrovanne demande à la wastegate de s'ouvrir à 100%. Dès lors les turbos ne sont plus freiné de manière à atteindre le plus vite possible la pression demandée. Seulement à un moment lorsqu'ils commencent à charger, ils arrivent rapidement à la pression et il est impossible de les freiner directement. Il y a donc un dépassement de la consigne ce que l'on appelle un overshoot. Ensuite il y a une régulation du boost ordonné par le calculateur sur l'électrovanne qui elle, agit sur la wastegate."
http://forum.motorsport-passion.com/...e/#entry394721

Two remarks about this Belgian tuner comment:

• it is indeed confirmed everywhere that the M mode (M-button) is another mapping than stock (remapping); however unsure about the tuner's reference to M Mode when talking about overboost (except if mistaken, overboost is activated regardless M Mode: it only requires pedal to the metal);
• tuner removes overboost after tuning the engine management, otherwise the high level of torque and temperature could become unhealthy for the clutch and turbos longevity ("Après préparation, nous supprimons l'overboost, sinon nous aurions trop de couple ce qui serait mauvais pour l'embrayage mais aussi les turbos (température trop élevée)"); wondering whether other tuners act likewise as precautionary measure.

See also (N54 135i versus N54 1M) (diagrams): http://www.n54tech.com/forums/showthread.php?t=13768

Most psi enthusiasts check the boost pressure in real time with the OBD-II CANBUS (P3 gauge).

[Dackelone]

Has anyone confirmed that the electronic P3 vent gauge reads true boost pressure? Compared to a pressure reading from the intake manifold.

I thought I remembered seeing a old post (on a 135i) that it readings are slightly off. Or maybe that was using a BT/OBDII port boost pressure vs intake manifold. ??? Also... any gauge must also see "boost spikes" during up or down shifts.


Dack

[///M1]

Originally Posted by Dackelone

Has anyone confirmed that the electronic P3 vent gauge reads true boost pressure? Compared to a pressure reading from the intake manifold.

I thought I remembered seeing a old post (on a 135i) that it readings are slightly off. Or maybe that was using a BT/OBDII port boost pressure vs intake manifold. ??? Also... any gauge must also see "boost spikes" during up or down shifts.


Dack

When I had the Accessport I'd compare its readings (off the ECU) with my P3 (version 1) boost gauge, which would take a physical reading off the DVs. They were reading generally within a 0.1-0.3 psi difference, which seems pretty uniform to me.