BMW is earning quite the reputation of underrating its turbocharged engines. From the early days of the N54 twin-turbo inline six, through the later N55 single-turbo iteration and straight on to the 2012 M5's turbocharged V8, the crafty Bavarians have always erred on the low side with their factory-quoted power figures.

According to the dyno run that you'll see after the break, the tradition continues with BMW's new twin-scroll turbocharged four-cylinder inline N20 engine that sees duty in the 2012 328i. The mill is rated at 240 horsepower and 255 pound-feet of torque, and on at least one Dynojet dyno, a stock 328i put down 226 horses and 230 lb-ft.

Assuming that around 15 percent of power is lost to the various friction forces of the drivetrain, these results indicate that the engine is really spinning out 265 horsepower and 270 pound-feet of torque. Those are mighty impressive figures, and equal about 25 more horses than stock and at least 15 more lb-ft of torque. Suffice it to say, this engine is an extremely tempting proposition for future 3 Series owners.


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    • 1 Second Ago
  • 158 Comments
      AnthonyL
      • 3 Years Ago
      15% is one big assumption to make, especially in 2012. That's the same thing as saying a car needs its oil changed every 3k miles.
        streve cook
        • 3 Years Ago
        @AnthonyL
        Remembering some articles I've read in the past suggested about 6%-7% loss from the the fly to the rear wheel.
        AcidTonic
        • 3 Years Ago
        @AnthonyL
        You clearly don't drive a high boost turbo car then.... I change my oil every 2000 miles. Sure I was running 20psi+ and making well over 300 at the wheels from a 2.0...... Sports cars in general still need more frequent oil changes.
      Perry Harrington
      • 3 Years Ago
      What is more likely is that BMW rated the engine according to the torque limiting for gears 1 and 2. When you get up to 3+, they typically remove torque limiting and that results in much more torque/power.
        me
        • 3 Years Ago
        @Perry Harrington
        BMW have never done torque limiting in the past. Hence why there entry level car gets a 5.6 0-60 which beats several other cars with more HP.
      Mike F.
      • 3 Years Ago
      To the Cadillac ATS 2.0T: the gauntlet has be thrown! Can't wait to see how these two compare.
      SethG
      • 3 Years Ago
      I know that the 15% drivetrain power loss figure has been a rule of thumb in making these sort of estimates. But many manufacturers (including I'm sure BMW) have been looking to reduce drivetrain losses along with all other efforts to increase performance and efficiency. If the 328 has drivetrain loss closer to 10% then the numbers start to feel about right.
      Scarboy6693
      • 3 Years Ago
      Frankly with the Last gen, I'd have never considered the 328i, rather have the Turbo V6. Now It actually seems like a tempting option, great milage and enough power for getting around town. I wouldn't get it stripped out though. I'd go for the sport line 328i w/ nav, premium package, and xenon lights. Good enough tbh.
        Rotation
        • 3 Years Ago
        @Scarboy6693
        You mean turbo I6.
        RocketRed
        • 3 Years Ago
        @Scarboy6693
        "enough power for getting around town" Your town must have no cops. As for the options argument, BMW is fully aware of your principled stand. Which is why Xenon, NAV, etc, all the goodies, is knocking on 45K in that car. At this price, the performance seems much less awesome and now you are running with G37s and the like for a 10K premium.
          • 3 Years Ago
          @RocketRed
          [blocked]
        simianspeedster
        • 3 Years Ago
        @Scarboy6693
        Yeah, the G37 is definitely the closest real competitor to the 335i with all its power and RWD. It's also a relative bargain, but there are some natural compromises for the savings. The overall feel of quality is not the same on the G37 and the engine is far rougher overall and not as tractable in the midrange as the N55. That and BMW knows they can charge a premium for the badge, so they do. If Infiniti ever produces a car that really matches the 335 point by point for 10-15% less $$$, it will be interesting to see how it affects the market. Now that the F3X is here, Inifiniti has to play catch-up again.
      AnalogJesse
      • 3 Years Ago
      Pretty incredible what a well-engineered 4 cylinder engine is capable of these days. If only cars were getting lighter...
        kornkid8600
        • 3 Years Ago
        @AnalogJesse
        The new 3 series is about 100 lbs lighter than the old one, while being bigger. It's a start though. I'm starting to see Audi and MB start taking weight seriously too, a lot of their more expensive models are going aluminum in a lot of places shedding lots of weight.
          aidanlax9
          • 3 Years Ago
          @kornkid8600
          No it's not. http://www.edmunds.com/car-comparisons/?veh1=101288737|sedan&veh2=101386360|sedan&show=0|1|2|3|4|5|6|7|8&comparatorId=9309774
      Larry W
      • 3 Years Ago
      The dyno run was in STD, how about doing it in SAE to show more true numbers. Of course STD will be higher. Come on AB!!
        Dipstick!
        • 3 Years Ago
        @Larry W
        Noob here: Care to explain what STD and SAE are? Right now, it feels like I'm in some awkward sex education class. Thanks!
          Larry W
          • 3 Years Ago
          @Dipstick!
          They are different ways the dyno can measure the HP and TQ. SAE is the most accurate method. The STD method will typically show 4 to 6 % more HP and TQ than SAE numbers due to the way the power is factored. Many places will show STD just to make their numbers look bigger.
          Larry W
          • 3 Years Ago
          @Dipstick!
          My percentage may be off. It's been a while since I looked into it. :)
      Amco
      • 3 Years Ago
      My next car! Thank you bmw for making the 328i perform as well or better then the old 335i
        genelamont
        • 3 Years Ago
        @Amco
        Guess they're not going to sell a lot of 335's for a while...
      Rotation
      • 3 Years Ago
      You can do anything you want with guessing and correction factors on road dynos. Give up on this stupid stuff. The important thing is the performance. Whether it "really" makes 270HP or 240HP or even 160HP, you don't care, you only care about the performance.
      jcar302
      • 3 Years Ago
      I think there should be a rule here at autoblog, don't post anything hp related about any car that makes less than 300hp and weighs more than 3200lbs. Reason? Nobody give a crap. So it's less slow, great... If this were 10 years ago, this would be news, but for god sake the v6 mustang makes more power than this car.
        Shiftright
        • 3 Years Ago
        @jcar302
        Wow, you are completely clueless as to what a driver's car is.
          Noah
          • 3 Years Ago
          @Shiftright
          And wow, you are completely clueless as to what a driver's car is not. (Clue, it's not the 328... go drive one! Then go drive the M3, or even just the 335... Don't forget to come back and fill us in on what a driver's car is...)
        Ali Zein Yousuf
        • 3 Years Ago
        @jcar302
        The V6 Mustang has a solid rear axle. Infact, all Mustang's have solid rear axles. Hello, the 19th century called, they want their suspension tech back! If you think the only joy in a car is straight line speed you are sadly mistaken. Also, lets not forget what the true charm of the 3 series is: It's actually a very sensible car. Need to take the kids to school? check. Gotta go grocery shopping? check. Cross country trip? check. But on top of all that, jab your right foot and start pulling some corners and you've got yourself a pretty fun car to throw around. Is it an M3? no. But for half of the price of an M3 is it a hell of a lot of car? You bet your ass it is. Remember, not all of us can afford the MSRP/insurance/fuel for a fire breathing biturbo inline 6 super salon.
      BDolman
      • 3 Years Ago
      Yeah, but its still a BMW, rich kids buy them, and dont care about the crazy maintenance costs on these overrated cars, deny it, but you know its true.
        simianspeedster
        • 3 Years Ago
        @BDolman
        Yes, the primary buyer of BMWs is rich kids who don't care about maintenance... Meanwhile, on planet earth, the primary buyers are working professionals who take full advantage of the free included maintenance for the first 4 years / 50,000 miles.
        Scarboy6693
        • 3 Years Ago
        @BDolman
        unfortunately that's very true, especially in Socal. Most of the 3-series, C-class, and A4s here are complete stripper versions. No options, just the cheapest one they can buy just to have the badge. If you're gonna buy a luxury car, go for one with some options on it at least..
        genelamont
        • 3 Years Ago
        @BDolman
        you forgot douches. rich kids and douches.
      Justin Campanale
      • 3 Years Ago
      And one more thing, can BMW PLEASE stop using this retarded naming system? 328i should be 320ti. 335i should be 330ti 550i should be 544ti Etc.
        MANARC100
        • 3 Years Ago
        @Justin Campanale
        i agree 100%
        • 3 Years Ago
        @Justin Campanale
        [blocked]
          • 3 Years Ago
          BMW's naming schemes *used* to imply engine sizes in liters. 323i = 3 series 2.3L motor. 330i = 3 series 3.0L, etc. Of course, that went completely out the door when BMW re-adopted nondiesel turbo motors (335i, etc).
          • 3 Years Ago
          [blocked]
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