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    • Watch out for the B's - Comparing the upcoming B48 2.0 liter turbo four-cylinder to the N20 it will replace - Bore x stroke + specifications

      BMW will introduce a new B-Series of modular engines for the 2015 model year. The idea is for BMW to keep costs as low as possible by having each B-Series variant displace 500cc's per cylinder. Since you are good at math you know this means a 4-cylinder will have 2.0 liters of displacement and a six-cylinder 3.0 liters.


      It also means BMW can use the same pistons and rods for every variant. A 1.5 liter three cylinder, 2.0 liter four-cylinder, and 3.0 liter six-cylinder will all have the same internal parts to keep costs down. They all will also obviously share the same 82mm bore and 94.6mm stroke.

      The N20 being replaced has a bore of 84mm and a stroke of 90.1mm. BMW is going to an even more undersquare design. Considering these motors will all be turbocharged BMW is not looking for revs. They are looking to keep revs low and torque down low high for fuel efficiency.

      The engine design is all about keeping costs low along with emissions. The B48 will offer VANOS and Valvetronic just as the N20 currently does.

      The motor is already in use in 2014 Mini products and the BMW 2-Series Active Tourer will see the engine for the 2015 model year. All BMW 28 models are expected to be upgraded to the 30 designation so for example a 228 would change to 230 for 2015 denoting the new motor.

      In Mini Cooper JCW trim the B48 puts out 234 horsepower and 258 lb-ft of torque. The N20 in the 28 models is rated at 241 horsepower and 258 lb-ft of torque although we know this is underrated.

      The B48 on paper at least will exceed this output with 255-265 horsepower and 295 lb-ft of torque. Not a huge horsepower gain but a fairly decent torque jump. It certainly looks like BMW is all about low end torque these days and keeping revs low. We will have to see a dyno plot to know for sure but it is unlikely for BMW to take a step back in power and torque from the N20.

      It remains to be seen if the B48 is tuner friendly although the N20 has hardly received as much attention from tuners as one would expect. With it being replaced so quickly and the B-Series expected to stick around for quite a while the B48 will likely see more attention from the aftermarket in time.

      The N20 has won two International Engine of the Year Awards although the M133 from Mercedes-AMG took its crown as expected. The B48 would need to be something special to be able to compete in the 2.0 liter category and from what we see so far VW, Audi, and Mercedes all have much stronger 2.0 liter motors at this time.

      The B58 will be the six-cylinder variant set to replace the N55 inline-6 and we will take a look at that motor in comparison to the N55 once more information is available. One can basically take a B48 and add two cylinders to get an idea of what the B58 will offer.
















      This article was originally published in forum thread: Watch out for the B's - Comparing the upcoming B48 2.0 liter turbo four-cylinder to the N20 it will replace - Bore x stroke + specifications started by Sticky View original post
      Comments 52 Comments
      1. subaru335i's Avatar
        subaru335i -
        Definitely looking forward to more info about the B58 and how it is different than the N54/55.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by subaru335i Click here to enlarge
        Definitely looking forward to more info about the B58 and how it is different than the N54/55.
        It's just basically going to be the same thing as the B48. Same bore, same stroke. BMW can bump the HP anywhere between 330-380.
      1. inlineS54B32's Avatar
        inlineS54B32 -
        I know it's an FI engine and all, but it's pretty impressive to make 295 ft-lbs of torque out of a little 2.0 liter engine. When you realize that an STi is making less torque with another half a liter of displacement, and is likely tuned for similar low-end grunt, it seems that BMW is making some serious strides in the turbo/engineering department.

        Now, this doesn't mean they should only make FI engines. Are you hearing me @BMWUSA!!! Click here to enlarge
      1. Sticky's Avatar
        Sticky -
        The M133 makes 331 lb-ft and VW is readying a 370 lb-ft motor.
      1. black bnr32's Avatar
        black bnr32 -
        neat pics. the gas and diesel motors sure look different in the turbo and piston department. it would be fun to play with the tuning of the variable geometry turbine on the diesel.

        and wtf is with the heavily necked down ports on the gas motor? never seen that before. it must create much higher air velocity.

        and coolant ports between the pistons in the block? huh.
      1. inlineS54B32's Avatar
        inlineS54B32 -
        Yeah, good point... I guess it's not too impressive when looking at it like that. Things are crazy in the car world; come along way in 5 years.
      1. Flinchy's Avatar
        Flinchy -
        Click here to enlarge Originally Posted by black bnr32 Click here to enlarge
        neat pics. the gas and diesel motors sure look different in the turbo and piston department. it would be fun to play with the tuning of the variable geometry turbine on the diesel.

        and wtf is with the heavily necked down ports on the gas motor? never seen that before. it must create much higher air velocity.

        and coolant ports between the pistons in the block? huh.
        i'd assume keeping velocity up for low revs

        sucks ass for peak/high revs power though.
      1. deathtracks's Avatar
        deathtracks -
        Interesting that both the diesel and gas engines pictures have variable turbine nozzles. I expected that on the diesel but not the gas engine replacement since the exhaust runs so much hotter. Should reach boost target right off idle. 295 ft lbs right at off idle in a 2.0 gas engine will be a good thing and with the variable turbine nozzle it shouldn't choke as much at the higher end.
      1. maxnix's Avatar
        maxnix -
        More undersquare is not encouraging. Probablpy smaller valves too. Funny, that specification was not mentioned.
      1. maxnix's Avatar
        maxnix -
        Click here to enlarge Originally Posted by inlineS54B32 Click here to enlarge
        Now, this doesn't mean they should only make FI engines. Are you hearing me BMWUSA!!!
        A very basic understanding of physics will immediately reveal to you why the NA engine is dead as a thermally efficient engine design. Click here to enlarge
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by maxnix Click here to enlarge
        A very basic understanding of physics will immediately reveal to you why the NA engine is dead as a thermally efficient engine design. Click here to enlarge
        I don't buy M cars for efficiency. I was attempting to buy the Ultimate Driving Machine.

        At least the Americans are producing some truly epic NA engines.
      1. maxnix's Avatar
        maxnix -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        I don't buy M cars for efficiency. I was attempting to buy the Ultimate Driving Machine.

        At least the Americans are producing some truly epic NA engines.
        And Ferrari and Porsche don't? Click here to enlarge HP/torque per unit of combustion chamber volume? Click here to enlarge

        Today's superior engine controls, largely put in place to meet EPA and EU fuel economy requirements, have produced the incredibly efficient and powerful engines we now have.

        Now there are no BMW M cars produced that are NA and there will never be such engines again. And all of the turbo M cars will pretty much smoke their immediate NA predecessors and still attain 10% or more economy in steady state operation.

        I mean, why did you create boost addict?

        Honda lawn mower engines are safe for a few more years though! Click here to enlarge
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by maxnix Click here to enlarge
        I mean, why did you create boost addict?
        It's an automotive performance site. It isn't just about forced induction. Plus the M3 was NA and you can boost it right?

        Click here to enlarge Originally Posted by maxnix Click here to enlarge
        And Ferrari and Porsche don't?
        Ferrari is going to turbos and Porsche no longer uses a Motorsport based block. Cost cutting is affecting them as well.

        So, yes, the Americans now are producing the best NA motors in the world.

        Click here to enlarge Originally Posted by maxnix Click here to enlarge
        And all of the turbo M cars will pretty much smoke their immediate NA predecessors and still attain 10% or more economy in steady state operation.
        That doesn't mean they are more fun to drive.
      1. inlineS54B32's Avatar
        inlineS54B32 -
        Click here to enlarge Originally Posted by maxnix Click here to enlarge
        A very basic understanding of physics will immediately reveal to you why the NA engine is dead as a thermally efficient engine design. Click here to enlarge
        A very basic understanding of physics will immediately reveal to you that putting MORE "THINGS" between the intake port and the outside/intake (opposite of dethrottling) increase lag, reduce "negative" torque (engine braking), and overall just does not enhance the spirit of a "race" engine in any way whatsoever. Yes, it's getting better - but the S55 (or any turbo car I have driven) is not as sharp as say an S54 or an S65. They are LEAP years apart. Some people care about this (me), some people don't. I track my car when I can - and like the ability to balance the car at it's limit with the throttle. It's laughably easy with an NA M engine - now add any lag/delay/unknown power spike to the mix? It's just not as good - period.

        If we are looking for "thermally efficient engine design" (whatever this means), we would all be driving turbocharged diesels. They are LEAPS AND BOUNDS more "thermally efficient" than any petro based turbo engine - made by M or otherwise.

        I care about the sport, not what's thermally efficient. Christ, this isn't "prius boost".
      1. inlineS54B32's Avatar
        inlineS54B32 -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        So, yes, the Americans now are producing the best NA motors in the world.
        Yep, this is true. Just drove the C7 for a few days in Florida, and still can't get over how good that engine was. For 70k, I would bet there is not one car that can compete for the price/performance factor.
      1. inlineS54B32's Avatar
        inlineS54B32 -
        And by the way, about this whole "turbocharged era" - this has happened before in the 70s during the oil crisis. This is where things like the 300zx, Supra, RX-7, etc. came from. To say that the naturally aspirated engine is dead - when NA is mandated by all major motorsport regulations is absurd. Yes, F1 has turned to hybrid/turbo - and this is great. However, if you think that NASCAR, V8 Supercar, etc. are all going to go to FI just because ... umm, just because - that's absurd.

        It will be around for a long time, if not for as long as the Otto cycle engine is still around.
      1. maxnix's Avatar
        maxnix -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        It's an automotive performance site. It isn't just about forced induction. Plus the M3 was NA and you can boost it right?
        Internally, boosted engines are built differently than NA engines. One adds boost to them only at one's own risk.


        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Ferrari is going to turbos and Porsche no longer uses a Motorsport based block. Cost cutting is affecting them as well.
        But still, when one looks at specific NA performance, their NA engines are much more powerful per unit volume than any American ones excepting the new Ford Coyote V8 which follows many of the European precepts.

        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        So, yes, the Americans now are producing the best NA motors in the world.
        NeEver have. Americans always rely on cubic inches over volumetric efficiency. You seem to have missed that this is the point of my whole comment.



        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        That doesn't mean they are more fun to drive.
        F80/82 have a better chassis, standard and optional brakes than the E90/2 M3, so if a driver doesn't appreciate these differences alone apart from the more powerful engine, that is a personal problem for the driver and his sense of joy.
      1. maxnix's Avatar
        maxnix -
        Click here to enlarge Originally Posted by inlineS54B32 Click here to enlarge
        To say that the naturally aspirated engine is dead - when NA is mandated by all major motorsport regulations is absurd.
        Yes, the retrogressive regulations of most racing formulas (gotta love the NASCAR antique muscle car series, especially the ones that never existed!) are there to contain cost of development, but how many of us drive from point to point in the real world on a racing track every day? Z E R O !

        Racing regulations have no bearing on what is driven on the street where the populace actually uses their cars. Only the government does.
      1. BavarianBullet's Avatar
        BavarianBullet -
        Click here to enlarge Originally Posted by deathtracks Click here to enlarge
        Interesting that both the diesel and gas engines pictures have variable turbine nozzles. I expected that on the diesel but not the gas engine replacement since the exhaust runs so much hotter. Should reach boost target right off idle. 295 ft lbs right at off idle in a 2.0 gas engine will be a good thing and with the variable turbine nozzle it shouldn't choke as much at the higher end.
        The gasoline engine turbo pictures are twin-scroll only with no variable geometry turbine. The diesel is single scroll with VG turbine.

        The pix aren't labelled so it's hard to tell but just look for single vs twin scrolls.
      1. BavarianBullet's Avatar
        BavarianBullet -
        Click here to enlarge Originally Posted by black bnr32 Click here to enlarge
        neat pics. the gas and diesel motors sure look different in the turbo and piston department. it would be fun to play with the tuning of the variable geometry turbine on the diesel.

        and wtf is with the heavily necked down ports on the gas motor? never seen that before. it must create much higher air velocity.

        and coolant ports between the pistons in the block? huh.
        The intake ports aren't necked down, it's just the way they chose to cut and cross section the head to show it off. They are fairly standard ports.

        The hottest part of the bore is the top obviously so the coolant parts are there apparently for that. What I'm interested in is what the cylinder wall is made out of. From the pictures there is no thick alloy cylinder liner but instead appears to be some sort of alusil/nikasil type hard electroplated coating. So the bore spacing is much wider, more alum is present in between the cylinders and without the cooling ports, the aluminum may have reached a high enough temp to cause problems. Thus the cooling ports.

        What remains to be seen is if the cylinder is any weaker vs using a standard liner if this is all true.