Boost Request Offset Definition

mj6234

Lurker
Nov 25, 2020
21
1
0
After doing a bunch of reading and trying to better understand this table, I am questioning if the formula for the table is defined properly. In the general XDF, it is X/100 and the table is labeled as a %. We know lowering the decimal value increases boost target (among other things). Someone looked into the DAMOS and the table definition when translated from German was something along the lines of "Cylinder Filling Volume" or something - which points to it being more of a VE table. That being said, doesn't it make a lot more sense to make the equation 1000000/X and show the value as a true %? To me it seems more logical when you increase above 100 (which I guess would be the base), that VE is increased.

This might be semantics I guess, but seems more logical to me to define it this way (meaning increase the value and get a raised boost target). I think the way the stock tables are modeled, it sort of does make more sense this way (at least to me). Any other thoughts?

Here is what it looks like with the new equation.
 

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Yamahar1

Lurker
Feb 25, 2019
14
0
0
Ride
335i
After doing a bunch of reading and trying to better understand this table, I am questioning if the formula for the table is defined properly. In the general XDF, it is X/100 and the table is labeled as a %. We know lowering the decimal value increases boost target (among other things). Someone looked into the DAMOS and the table definition when translated from German was something along the lines of "Cylinder Filling Volume" or something - which points to it being more of a VE table. That being said, doesn't it make a lot more sense to make the equation 1000000/X and show the value as a true %? To me it seems more logical when you increase above 100 (which I guess would be the base), that VE is increased.

This might be semantics I guess, but seems more logical to me to define it this way (meaning increase the value and get a raised boost target). I think the way the stock tables are modeled, it sort of does make more sense this way (at least to me). Any other thoughts?

Here is what it looks like with the new equation.
Can you contact with me on fb or email for damos and to explain me this boost offset
 

P33P33

Private
Apr 3, 2017
45
10
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Ride
BMW 335i n54 e93
Here's the logic behind this table. There's many screenshots of the logic path and the one circled in red is the reason why lower values in the table raise boost target. To get a hang of this you can assume Ps_sollgd_nl2 is boost target. There's lots of steps after this until the final boost target is determined.
 

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Yamahar1

Lurker
Feb 25, 2019
14
0
0
Ride
335i
Here's the logic behind this table. There's many screenshots of the logic path and the one circled in red is the reason why lower values in the table raise boost target. To get a hang of this you can assume Ps_sollgd_nl2 is boost target. There's lots of steps after this until the final boost target is determined.
Can you contact with me on email ?
 

impuls

Specialist
Jan 28, 2018
91
57
0
Ride
'07 335i
If you consider that the DME is trying to get a specific amount of air into the cylinder the current definition does make perfect sense.
With higher VE getting the same amount of air into the cylinder does require less boost and the DME will request less boost.
 

mj6234

Lurker
Nov 25, 2020
21
1
0
If you consider that the DME is trying to get a specific amount of air into the cylinder the current definition does make perfect sense.
With higher VE getting the same amount of air into the cylinder does require less boost and the DME will request less boost.
That actually does make a lot of sense. I think the way I was interpreting the numbers was the higher the VE the higher the value, but hadn't thought about it the way you put it.
 

mj6234

Lurker
Nov 25, 2020
21
1
0
That actually does make a lot of sense. I think the way I was interpreting the numbers was the higher the VE the higher the value, but hadn't thought about it the way you put it.

OK, after actually playing with this, it is the higher the VE the higher the value. I just was thinking about it wrong again. lower value = lower VE = more boost required to meet load request = higher boost target is what you were trying to tell me.

Also (probably obvious to everyone else) VANOS changes change which cell is hit here.

Also I am well into flash tuning my own car from the stock file. First time I have tuned anything and think I have a good handle on things. I have upgraded turbos, N20 TMAP, and all of the normal bolt ons. I will post up a separate thread when the 91 pump file is done.