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Old 11-29-2012, 07:32 PM
m6pwr m6pwr is offline
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Location: San Diego, CA
Join Date: Jan 2008
Posts: 302
Mein Auto: '14 335i M Sport
Both N54 and N55 have aluminum blocks with cast iron cylinder liners.

FWIW the ADF team ran an e90 335 in the Bridgestone Production Car series in 2011 and it had a stock N54 putting out 300 hp (maybe they thought the N54 wasn't strong enough to run a full season of racing in modded form ). Just joking!

I don't know the particulars of the N55 turbo mods the team ran in 2012, and how the series they ran in differed, if at all, re mod restrictions. It may have been technically possible to do mods that produced greater power/torque but not possible under the 2012 rules of the series.

As I mentioned, I think it was realized at the outset that the N54 is more tunable (based on my memory of an article in the CCA mag Roundel when the N55 first came out) . But in stock form I think the N55 is easily the equal of the N54. I had a Z4 N54 with the Dinan Stage II mod (385 hp and 424 lb ft torque). With the 7 speed dual clutch tranny it was a rocket ship. But all that added boost had its price. I did used oil analysis and the percent fuel dilution went thru the roof. Didn't keep the car long enough to know if that might ever have had any deleterious effect in the long run.

Me - - I'm perfectly satisfied with the N55 in stock form in the 535 Msport. Great engine, great car. And I'm reasonably confident that if I keep it, it will last a long time. Will I have to worry about intake deposits? Hopefully not with the redesigned crankcase ventilation. Will the injectors last longer than 75-100k mi? Will the turbo last any longer? Don't know. Time will tell.

Last edited by m6pwr; 11-29-2012 at 09:21 PM.
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