Originally Posted by jsmonet
bmw engineered the factory intake to function responsibly, efficiently, at 8lb of boost. even the least aggressive tunes turn that up to 12+, and most people are running something between 14 and 17lb. granted this isn't a huge turbo so you're not pulling world-shattering cfm, but there's a chance to outrun the efficiency of the stock filter in that scenario..
- we diesel owners then must have a major problem as we have these boost levels on box standard engines:
N47 (my engine): 22.5 psi (I reckon my remapped car is at 30psi+)
M57 (the 335d): 28 psi (I don't want to know at what level a tuned 550lbsft 335d is..)
N47 twin turbo (the 07 onwards model with really two turbo's): 29 psi
I can't read my actual max. boost pressures, as the pressure sensor I have only goes to 255 kPa = 37 PSI = 22.5 boost + 14.7 atmospheric.