[sspade]

Finally getting acquainted with the Sensor Values feature in BimmerLink...

Was wondering if this seems normal to you guys:

Fully warmed up, boost pressure at idle is 14.924 psi

[MacklinUSOB]

That is really odd.

You should have vacuum at idle because the turbo is not pushing air in, the engine is pulling it. Sure it's not reading -14?

[rjd_F30]

Either it's not reading correctly or it's saying -14 like the above post mentions. At idle you should see a vacuum which is expressed as negative boost pressure.

[bheng89]

curious what it is when you are going WOT and if its going to be 34psi (or whatever you BM3 guys have boost set to)

[sspade]

Appreciate the responses...

This is what Im going off of.

I believe all other sensor readings are accurate...

The exact title of this reading is Boost Pressure Setpoint?

Can we form a question that I can ask the developer?

[MacklinUSOB]

Originally Posted by bheng89

curious what it is when you are going WOT and if its going to be 34psi (or whatever you BM3 guys have boost set to)

As far as I know N20/26 engines like to throw rods around or after the 24/25psi mark left unchanged. The most common upgrade path for people getting that serious is a big turbo, which people generally have set to peak between 23-25. 34psi would be incredibly impressive.

[rjd_F30]

Originally Posted by MacklinUSOB

As far as I know N20/26 engines like to throw rods around or after the 24/25psi mark left unchanged. The most common upgrade path for people getting that serious is a big turbo, which people generally have set to peak between 23-25. 34psi would be incredibly impressive.

I believe he's reffering to absolute pressure, which is the combination of ambient pressure (usually around 14) and boost pressure (usually around 16-23 depending on tuning/modifications). That's where the 34psi number comes from. But yes, 34psi relative pressure would send a rod into the stratosphere.

But to answer his question, on stage 2 OTS from PTF (BM3), my boost target is 22.85 at WOT and the car can hit that up until about 4000rpm, then boost tapers down all the way to 19-20 at redline as the turbo starts to hit it's flow rate limits.

[rjd_F30]

Originally Posted by sspade

Appreciate the responses...

This is what Im going off of.

I believe all other sensor readings are accurate...

The exact title of this reading is Boost Pressure Setpoint?

Can we form a question that I can ask the developer?

Interesting. Curious what it would read at WOT, should be around 15-17 depending on engine speed. You could test that to ensure that it's getting an accurate reading.

Anyway, as for a question to ask the developer, I would keep it simple and say: Why is the program showing 14psi (or 1,028 hectopascal ) of boost at idle when there should be vacuum at idle, i.e. negative boost pressure?

[sspade]

Originally Posted by rjdnyy224

Interesting. Curious what it would read at WOT, should be around 15-17 depending on engine speed. You could test that to ensure that it's getting an accurate reading.

Anyway, as for a question to ask the developer, I would keep it simple and say: Why is the program showing 14psi (or 1,028 hectopascal ) of boost at idle when there should be vacuum at idle, i.e. negative boost pressure?

Ill test again tonight after work before we all hit the track...

I remember the boost pressure definitely increasing under throttle but cant remember the reading.

What is the target boost pressure for our engines set at from the factory?

Is target boost the same as max boost?


ps. Should have a new addition to the ranking tonight if @n26ghost decides to run. Pretty excited about that and the fact that Diegov209 will be setting a new personal record with his vehicle!

[rjd_F30]

Originally Posted by sspade

Ill test again tonight after work before we all hit the track...

I remember the boost pressure definitely increasing under throttle but cant remember the reading.

What is the target boost pressure for our engines set at from the factory?

Is target boost the same as max boost?


ps. Should have a new addition to the ranking tonight if @N26ghost decides to run. Pretty excited about that and the fact that Diegov209 will be setting a new personal record with his vehicle!

Sounds good. Curious to see what the reading is under load, if it's right maybe the idle pressure is just a fluke/sorespot in the program.

The "target" from factory is 17psi, though I don't know how BMW codes their factory tunes (I suspect they do so with more complexity than aftermarket tuners), so I don't know if it's actually coded as a 17psi target. It could be written as 17psi is the limit, or it will reach and maintain 17psi at certain engine speeds, I really don't know. But for our intents and purpose the factory target is 17psi.

However, I do know that aftermarket tuning companies write boost parameters using a target, which is pretty self explanatory: the pressure value that the turbo will try to generate. The target isn't a max though, max is just the max boost that you make. You can overboost and exceed target, but a good tune won't let the car do that. Or you can not reach target and max will be below target. Ideally though, max is equal to target. However with the N2x because the turbo is so small, the target boost is only hit and maintained below roughly 4k rpm, at which point the turbo starts to lose breath and boost pressure will drop below target, assuming target is around 22-23, like it is for me. If your target is lower or closer to factory levels, the turbo should be able to get closer to maintaining that all the way up to redline.

Also: super excited to see how you guys all do tonight! Good luck