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      04-13-2010, 08:43 PM   #37
GeorgeSmooth's Avatar

Drives: 2008 E90 335i AT
Join Date: Feb 2008
Location: South Africa

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Originally Posted by Bob MG View Post
Gents I will be finished with my VT2 kit on Friday.
Instead of the 100mm pulley which boosts 5,5psi,
Roman supplied a 95mm pulley good for 6,5-7psi at sea level.

Based on the calculated loss of 0,17 bar or 2,46psi at 5000 ft, I would be safe to assume that my boost pressure will be between 4,0-4,5psi.

If it's closer to 4psi after dyno, we may contemplate a 92mm Which is normally a 7,5psi pulley at sea level.
92mm is the smallest pulley you can use with the VT blowers without changing belts and software.

Practical will be better than this speculation
Your drop will be the difference between barometric pressures. At 5000ft you should only loose .15 bar or approx 2psi. I know this from trial and error.
08 E90 335i AT RB Turbos -NX Wet Kit - Chiplogic Flash or Procede V5- M3 Diff - AE Exhaust- Forge Dv's - Helix Intercooler - AR DP's - P3 Boost Gauge - Vishnu Meth- Stett Chargepipe and CAI
09 C63