s50b30 Idle Vacuum

[Dejo325i]

Anyone know what the vacuum should be on a S50b30 while at idle?
Mine;
Engine stone cold: -10inches
Warm:-17 to -19inches

This is reading off the same hose that the fuel pressure regulator is connected to.
Compared to my old M50 these readings seem a few inches lower (cold;16" warm; 22-23")
Maybe because of the smaller vacuum manifold with it ITB's?
Do these readings seem normal?

[MauiM3Mania]

Good question. The cold numbers seem low in general, but the running temp numbers seem reasonable. The M50 is a much milder (cams, timing, compression) than the S50B30, even with VANOS, all which effect vacuum.

Next time I have my car out, I'll try to remember to check the vacuum.

[Dejo325i]

Thanks for the input. For a comparison I saw a few e46 m3 on YouTube with vacuum gauges.. And they seem to pull around -21"

[Dejo325i]

Just bumping this thread to see if anyone else has any input?
Changing the vanos solenoids to slightly newer units seems to have improved things a little. Can tell the way the engine runs and also now on cold starts the engine vacuum is no lower then 13" and warm is still the same; 17" - 19"