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      08-17-2011, 03:33 PM   #182
Beedub
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Drives: 2007 Z4 M roadster vt2-500
Join Date: Sep 2007
Location: UK

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Quote:
Originally Posted by iPhoneEngineer View Post
I don't believe it...in my boost test video, it was normal for the boost to spike a full 2PSI+ at the end of a redline pull. Can you get a passenger to take a video of the run itself rather than just using "Peak recall" which has been demonstrated to be inaccurate on these setups? My most recent dyno with an accurate boost plot also showed this uptick at the very end of the run.

Beedub, I think this probably applies to your peak recall too...the real test is knowing what boost the motor is running at with the throttles still fully open, just before the shift which causes immediate pressure fluctuations in the BPV.
i did alittle test to confirm accuracy..... firstly i "cleared" my peak and changed up at 7400 rpm and say precisely 7.4ish psi, i did the same numerus times with proper 7900 pulls WITHOUT popping the limiter and say 8.0psi+ on the peak..... if i bump the limiter i see the peak showing @ over 10.5psi...... i can gaurantee you im hitting 8psi+ @ 7900, me and my shop were at one point worried about it infact so i cantacted ess who said it happens......

i dont see any spikes on boost when driving, just a clean clear sweep of the gauge, when i bang the limiter, thats when i see the spike offs like you talk about....... which is one thing is ALWAYS noted (look back and see;-)) its veryeasy to see when it does that as it swings wildly as you pop the limiter, im talking about a clean NON redline run.... and every single time is see 8psi on those runs....... tom will see even more due to the raised rev limit

either way im hitting 7psi WELL before redline.........
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