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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Interpreting V2 Max Boost



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      01-11-2008, 03:11 PM   #1
andrewflk
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Interpreting V2 Max Boost

I’ve been searching the forum but I can’t find a clear answer on the following…

When I did a series of 2nd to 3rd gear data logs boost in 3rd gear read ~14.6psi gradually tapering down to ~14.0psi at 5500rpm with 90% settings. During all of these runs the 3rd gear pull started at 4200rpm. I’m at sea level, outside temp was 60F and I was able to duplicate these results several times.

In the V2 instructions to adjust the user torque table it states that the boost peak should steadily climb from ~10-12psi at 4500 and reach a peak at 5500. It also states the maximum not-to-exceed 15psi at 5500rpm. I have also seen other member’s posts with tapering curves (like Hokie hitting >15psi) and then others with rising boost curves as described in the V2 read me.

So is this tapering just a normal variance on my car? Is the rule 15psi at 5500rpm or just never exceed 15psi no matter what RPM?

By the way…the car feels awesome! I love the way V2 pulls and the fact that we have the ability to dial it in…I just want to see if I can adjust up a few more points.

This is an example boost log (Notice how I can’t keep traction in second gear):

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      01-11-2008, 03:16 PM   #2
ThomasMartin
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Quote:
Originally Posted by andrewflk View Post
I’ve been searching the forum but I can’t find a clear answer on the following…

When I did a series of 2nd to 3rd gear data logs boost in 3rd gear read ~14.6psi gradually tapering down to ~14.0psi at 5500rpm with 90% settings. During all of these runs the 3rd gear pull started at 4200rpm. I’m at sea level, outside temp was 60F and I was able to duplicate these results several times.

In the V2 instructions to adjust the user torque table it states that the boost peak should steadily climb from ~10-12psi at 4500 and reach a peak at 5500. It also states the maximum not-to-exceed 15psi at 5500rpm. I have also seen other member’s posts with tapering curves (like Hokie hitting >15psi) and then others with rising boost curves as described in the V2 read me.

So is this tapering just a normal variance on my car? Is the rule 15psi at 5500rpm or just never exceed 15psi no matter what RPM?

By the way…the car feels awesome! I love the way V2 pulls and the fact that we have the ability to dial it in…I just want to see if I can adjust up a few more points.

This is an example boost log (Notice how I can’t keep traction in second gear):

I Hate you guys at sea level with such flat torque curves so much air boost hardly drops
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      01-11-2008, 03:29 PM   #3
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I Hate you guys at sea level with such flat torque curves so much air boost hardly drops
Only problem is when racing NA cars... they are at full power too. Yall people up high might loose a little power but still crush the NA guys
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      01-11-2008, 03:35 PM   #4
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Yes the Taper is normal.
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      01-11-2008, 04:44 PM   #5
andrewflk
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I agree that the data logs I posted look healthy. I’m just curious as to why the variance from one car to the next regarding inclining or declining curves, and should I adjust my user torque settings by the 5500rpm boost psi? Or just peak regardless the rpm?

Shiv, can you comment on this?
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      01-11-2008, 04:52 PM   #6
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Quote:
Originally Posted by andrewflk View Post

In the V2 instructions to adjust the user torque table it states that the boost peak should steadily climb from ~10-12psi at 4500 and reach a peak at 5500. It also states the maximum not-to-exceed 15psi at 5500rpm.
I would follow the Instructions.
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      01-11-2008, 04:52 PM   #7
shiv@vishnu
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Quote:
Originally Posted by andrewflk View Post
I agree that the data logs I posted look healthy. I’m just curious as to why the variance from one car to the next regarding inclining or declining curves, and should I adjust my user torque settings by the 5500rpm boost psi? Or just peak regardless the rpm?

Shiv, can you comment on this?
I'd say the variance has 80% to do with differences in testing conditions and 20% to do with car to car differences. If you datalog your car on two different days, you'll get different results. Stock or modified. The variance does tend to increase the more power you make though. This is normal.

Shiv
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      01-11-2008, 05:26 PM   #8
andrewflk
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Thanks Shiv…Of course I was ultimately trying to see if I can increase my user torque settings but it actually sounds like there are so many variables that I should continue to do some more testing…Darn, I hate doing those full throttle mad acceleration tests again and again.
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