• BMW F30 320i N20 turbo 2.0 stock and modified dyno results from BMS - Full breakdown of 320i and 328i N20 shared components with part numbers

      BMW decided to introduce the 320i model in the United States which shares basically the same N20 turbocharged four cylinder 2.0 direct injected powerplant as the big brother 328i cousin. The 328i and 328i share the N20 motor with the same rods, crank, head, cams, turbocharger, exhaust manifold, and associated parts. What is different between the two? The pistons and the tuning of the ECU (engine control unit). Here is a full breakdown of the shared components with part numbers:

      Shared N20 2.0 engine components between an F30 320i and F30 328i:

      • Cylinder head - PN 11127624778
      • Connecting rods - PN 11247624616
      • Crankshaft - PN 11212212762
      • Intake manifold - PN 11617588126
      • Air box - PN 13717597589
      • Air filter - PN 13718507320
      • Intercooler - PN 17517618809
      • Radiator - PN 17117600520
      • Throttle body - PN 13547588625
      • HPFP - PN 13517584461
      • MAF - PN 13627602038
      • MEVD 17.2.9 DME/ECU - PN 12148604210
      • Exhaust manifold/turbo - PN 11657642469

      Does the pistons not being shared mean the 320i pistons are weaker? Who knows at this point. They have the exact same compression ratio but different part numbers. Interesting that BMW would go to the trouble of changing the pistons but nothing else. Does the N20 320i have a tuning disadvantage to the N20 328i? Not at this stage, check out these dynocharts.

      Here is the 320i N20 stock, yes, weaker than the 328i as it should be as the 320i N20 is rated at 180 horsepower and 200 pound-feet of torque versus 240 horsepower and 255 pound-feet of torque for the 328i N20:

      It gives up in the ~40-50 whp range versus a stock 328i N20. All through software. Look at the 320i with an increase of 3 psi of boost:

      Just like that approaching the 328i level with some more boost. Now let's look at an additional 4 psi and the Stage II 5 psi map:


      And now all of them in one graph:

      That is just about another 80 wheel horsepower with just some minor tuning. The F30 328i is not the best tuning value in the BMW lineup, the F30 320i is. Keep in mind pushing the N20 motor beyond Stage II is currently not recommended as there may be a head cracking issue past 331 pound-feet of torque.

      This article was originally published in forum thread: BMW F30 320i N20 turbo 2.0 fstock and modified dyno results from BMS - Full breakdown of 320i and 328i N20 shared components with part numbers started by Sticky View original post
      Comments 14 Comments
      1. E90Company's Avatar
        E90Company -
        Interesting. I would have thought it was the exact same motor.
      1. Sticky's Avatar
        Sticky -
        Just different pistons. This has pluses and minuses. BMW can distribute the same motors and just change software artificially controlling the lineup and prices. Larger profit margin for a different software file. It also means they can be lazy. Different models with the same motor just different tune like I have been saying would happen.
      1. chrisisnapping's Avatar
        chrisisnapping -
        i really want to know the reasoning behind switching the pistons. I mean that's not exactly an easy task. I mean swap manifolds, throttle bodies, but opening the engine for pistons?

        good work as always Terry! Now get a downpipe and intake on there and see what she can do!
      1. Puerto Rican 335d's Avatar
        Puerto Rican 335d -
        chris I beleive the nomenclature 328i vs 320i same as 335 and 335i, thats all a cheaper version lees money. Remember Dodge vs Chrysler, or Ford vs Mercury same platform different gadgets
      1. maxnix's Avatar
        maxnix -
        Some questions answered, many remain. Good post!
      1. ihc95's Avatar
        ihc95 -
        BMW isn't dumb though. You can't get the M-sport pack with the 320i, only the 328i. That alone is the reason I'd buy the 328i since I wouldn't want to retrofit the bumpers and steering wheel later on in the 320i.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by ihc95 Click here to enlarge
        BMW isn't dumb though. You can't get the M-sport pack with the 320i, only the 328i. That alone is the reason I'd buy the 328i since I wouldn't want to retrofit the bumpers and steering wheel later on in the 320i.
        Why bother with a stock BMW bumper when you can get a better aftermarket bumper with the change saved, wheels, brakes, etc.?
      1. leo985i's Avatar
        leo985i -
        No point in buying a 328 for anyone that knows about tuning then, unless you are a fan of having the "better" badge.
      1. krnnerdboy's Avatar
        krnnerdboy -
        Don't forget the 328's beefier axles and brakes
      1. sharkatron's Avatar
        sharkatron -
        Be interesting to see how the 320i pistons hold up to tuning...
      1. alex@ABRhouston's Avatar
        alex@ABRhouston -
        Ok so reading this over since i have two N20's getting connecting rods, I decided to compare them to some n54 rods and pistons I have floating around.
        they are the same bore, and the only difference is rod length. They make the difference up in piston pin height. With that being said, my custom connecting rods and pistons for the N54 will also work for the N20 as well, since they are the same overall length.

        and with THAT being said, that also means my custom rods and pistons should work in the 320/328 engines without an issue..... Other than we have to grind the crank to put our kick ass bearings in. This also means we can stroke/destroke the engines as well......

        so, we are waiting on the tuning market to get up to speed on the N20 engines..... And we can build engines to make em strong.

        i honestly think the N20 is going to be the next budget racer's engine at the track.
        light, decent power, and in little cars. We're waiting on some wrecked/totaled F30s to come along to make them into race cars Click here to enlarge
      1. morkusyambo's Avatar
        morkusyambo -
      1. onisyndicate's Avatar
        onisyndicate -
        Edmunds puts the 320i sedan at 3295 lbs curb weight and the 328i at 3360 lbs curb weight and for some odd reason the 328i coupe is at 3362 lbs curb weight. oh wait it has the inline 6 3.0 Click here to enlarge.

        Awd is 3450 for the 320i and 3595 for the 328i.

        So for the 2.0 Tunning and seeing which will run better it'll be a close toss up. But I think the AWD 320i tuned will beat the snot out of the AWD 328i! Just because of the 145 lbs deficit.

        At the end of the day a Tuned 320i and getting around 36 mpg highway and 24 city. would make a car with enough power to get around in traffic and do some highway passing without having to worry to much about the power!
      1. Leo's Avatar
        Leo -
        I wouldn't be surprised at all of the 328i had larger standard brakes than the 320i which would definitely be part of that weight difference.