philly_tee

Can anyone tell me what the stock boost pressure is for the C400. No tune, stock turbos.

I am trying to locate this info online and having a tough time finding it.

stockbmw

9 psi

philly_tee

@stockbmw thanks! This helps a lot!

Cyoulater

yeah thanks - a few months ago i tried for about 30 mins to find this

MatthewJ

It will vary depending on the weather. Progressive map is to try and keep the car seeing the same air in different conditions.
My C400 ECU commands between 9 and 10PSI. On the JB4 graph its looks like the ECU has the boost tapering off after a shift. Starts high around 9.5 and drops down to 7.5 for the next shift.

philly_tee

@MatthewJ thanks for responding. I have recently installed a jb4 on my c400 and would love to see some of Your logs. Map 2 I’m hitting around 11-12psi with 94 octane. That seem low?

MatthewJ

Assuming you have the latest firmware, that would be a little low but again it depends on weather and altitude. Most C400's with good fuel available to them can daily map 4. That puts us around where the 2020's are stock for boost.
Do you have an intake?

From BMS site:
JB4 Map Guide as of v6 firmware:
Map 0: Disables tuner
Map 1: Up to 4psi over stock peak, suitable for all 91 octane+ fuels
Map 2: Up to 5psi over stock peak, suggested for 93octane+
Map 3: Up to 5.5psi over stock peak, slightly more aggressive version of map2
Map 4: Up to 6psi over stock peak, suggested for E30+ or unleaded race gas mixtures
Map 5: Up to 7psi over stock peak, holding more boost to redline, suggested for E30+ or unleaded race gas mixtures
Map 6: User definable map, boost over stock entered on user adjustment page
Map 7: WMI (water/meth injection) progressive map for BMS FSB integration
Map 8: Low boost VALET map

philly_tee

Hey @MatthewJ , yeah I just installed a BMS DCI last night. I haven't really done any long pulls or anything as of yet tbh. I do feel it mid to high end, but low end boost isn't really there. I updated the firmware to the latest stable one available. This morning on my drive into work I used map 3 and hit it once on the hwy, definitely felt it.

I'd love to see a log of your low end boost and daily driving. My boost is always at 0-1 when not hammering it, does that seem right? I mean, I can hear it charge up and release with the intake but the logs just don't show anything until I go WOT.

MatthewJ

One of my map 6 logs here. Are you looking at ECU Psi, target or boost?
When taking a log its recommended to do runs from like 30 to at least 70 to get a good picture of whats going on. BMS has always been responsive for me when emailing them logs.

Edit: you said daily driving, i have my JB4 set to only log WOT conditions. Ill post a different log with whole drive home all throttle conditions

MatthewJ

this is a test run i was doing after gold heat tape on the intake. other tab shows the raw data of the log

philly_tee

thanks so much for this @MatthewJ I'll take a look after work and when I am home tonight.

Yeah, Im clearly recording logs incorrectly because i'll just hit "start logging" and then drive around normally.

I need to do a proper log, and that will be in sport+ and from 30-70, we will see what happens then.

I appreciate you taking the time to respond to me - thanks

philly_tee

@MatthewJ is the gold heat tape providing a noticeable reduction in heat?

MatthewJ

Define noticeable lol. From the logging its keeping the IAT more consistent and slightly lower (8-10°F). Seat of the pants doesnt notice, but every little bit helps when 10°IAT = 1° timing removed after 80°.