BMW has replaced its popular N55 35i serious engines with the B58 40i motor.  These new motors produce slightly more power as found in the 240i, 340i, and 440i vehicles.  The new inline 6cylinder turbocharged engine produces 335 horsepower to the crank and 369 ft/lbs of torque.  With 15hp more than the previous M235I and 30hp shy of the M2, the new B58 platform is perfect for tuning.  BMW has made it quite complicated to do ECU flashing.  Right now OBDII port tuning is not an option.  To make this even possible, you still have to bench flash it by unlocking the ECU to where you can then write files via the OBDII.  However the ECU is not easily located.  So VRTuned has their new tuning box kits available.  These plug and play tuning box kits are very warranty friendly.  Not altering anything with the ECU, they plug into the cars boost pressure, manifold pressure, and camshaft sensors to boost up horsepower quite a bit.  Because the kit can be easily installed or removed, this makes it a top choice for new BMW 40i owners.

The horsepower ratings by the German manufacture are tested on 98 ron which is similar to the USA 93 octane. The manufacture rated the HP gain at 94 on 98 ron.  So this translates into about 79 horsepower to the wheels.  We decided to test this car on our Mustang dyno and with the lower quality 91 octane found on the western USA.  Typically the higher the octane you use, the car will always perform better, so this is a great real world test.  The Mustang dyno also gives you more real world road numbers.  Typical drivetrain loss for our dyno is about 15% in rear wheel drive.  The car baselined at 287 horsepower which is dead nuts on what 15% of 335 is.  Once the tuning box is plugged in, we completed the after test which gave some very exciting numbers.  Torque tremendously increased at 3725 rpm from 299 to 361 giving it a gain of 62 ft/lbs of torque.  This is a HUGE difference in your 0-60 time.  Horsepower equally saw a large consistant gain from 3300 to 5500 rpm only to be restricted by air flow and the massive catted downpipe.  In this RPM range, the car gained just over 40 horsepower to the wheels.  With a 15% drivetrain loss, this would equate to about 50 horsepower to the crank.

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About The Author

Dan Mermelstein - Co-Owner, Blogger, Porsche Enthusiast, VRTuned Marketing and Technical Support. Available to make your car faster!

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