The latest BMW engine: N55 – found in the BMW 5 Series GT

Others | May 26th, 2009 by 29
bmw biturbo01

The launch of the BMW 5 Series GT also coincides with the introduction of a new BMW engine, internal codename: N55. The new BMW Power …

The launch of the BMW 5 Series GT also coincides with the introduction of a new BMW engine, internal codename: N55. The new BMW Power Turbo uses a single twin scroll turbo instead of twin turbochargers as the N54 engine. The 2,979cc six-cylinder powerplant features for the first time High Precision Injection and variable VALVETRONIC valve management combined with the single twin-scroll turbocharger.

Even though BMW has not yet confirmed our suspicions, we believe the single turbocharger used in the 5 Series GT is the same as those fitted to the new 4.4 liter V8 engine in the X5M/X6M. Power and torque is similar to the twin turbo engine – 225 kW/306 hp at a speed of 5,800 rpm- but the 400Nm/295 lb-ft peak torque kicks in 1,000 rpm earlier at 1,200 rpm.

bmw biturbo01 498x373

N54 Engine Featured Here

Compared to the BMW turbo engine already well-known in the 335i, 535i and other models, the N55 engine offers even greater fuel economy combined with optimized CO2 management. The power unit of the BMW 535i Gran Turismo is the first turbocharged engine to feature a map-controlled oil pump which, taking up less energy, makes a further contribution to motoring efficiency.

We’ve also done some snooping around and asked some people, and the rumor is that in the near future, BMW will offer a twin-turbo engine with VALVETRONIC and Direct-Injection, which might produce close to 360 horsepower. Since we can’t confirm it 100%, take this with a grain of salt, but we’ll let you know as soon as we hear more.

Press Release

World debut:
TwinPower Turbo, High Precision Injection and VALVETRONIC in a new straight-six gasoline engine.

The new model is entering the market with a choice of two gasoline engines and one diesel power unit. In the process BMW’s newly developed straight-six gasoline engine for the fi rst time featuring turbocharger technology, High Precision Injection and variable VALVETRONIC valve management all together is making its world debut. Indeed, the intelligent combination of these three technologies gives this power unit the best and most direct response ever offered by a straight-six turbocharged engine from BMW.
The new BMW TwinPower Turbo develops 225 kW/306 hp at a speed of 5,800 rpm, maintaining its maximum torque of 400 Newton-metres/295 lb-ft over a wide speed range from 1,200–5,000 rpm and, in comparison with the BMW turbo engine already well-known in other model series, offering even greater fuel economy combined with optimised CO2 management.

The history of BMW’s modern turbo engines going back to the year 2006 is characterised by spectacular power and exemplary efficiency. And now BMW is opening up a new chapter in this history, the straight-six gasoline engine powering the BMW 535i Gran Turismo consistently continuing the process of optimising engine power while at the same time reducing both fuel consumption and CO2 emissions on an engine of this calibre.
The 3.0-litre power unit, for example, is yet a further result of the BMW EfficientDynamics development strategy, offering a range of highlights in technology never seen before on any other engine – highlights created in the context of BMW EfficientDynamics and now ideally matched for optimum driving dynamics and economy all in one.
The new straight-six is the world’s first engine to combine turbocharging, direct gasoline injection and fully variable VALVETRONIC valve management developed by BMW. The turbocharging process follows the twin-scroll principle already applied successfully by the BMW Group and now further enhanced consistently for use in a particularly powerful and sporting straight-six.
The combination of this turbocharger technology with High Precision Injection and VALVETRONIC exclusive to BMW exceeds even the response and efficiency of the BMW Twin Turbo power unit launched back in 2006.

Response even better than before, fuel consumption even lower.
VALVETRONIC has already proven its qualities in numerous BMW engines the world over as a particularly effective technology providing even greater efficiency. The big advantage of VALVETRONIC is the infinite control and adjustment of valve stroke on the intake valves, making the throttle butterfly used in former times superfl uous. VALVETRONIC reduces throttle losses in the charge cycle process to an absolute minimum and optimises engine response since the air mass required to control the combustion process is masterminded in the engine itself and not outside the power unit with the usual “dead” volume. This ensures particularly efficient use of the energy contained in the fuel, developing a very muscular torque curve and giving the engine optimum response. In particular, the better response of a VALVETRONIC engine results from the fact that underpressure under part load is only approximately 50 millibar, while on a conventional engine up to 800 millibar of underpressure has to be set off.
On the BMW 535i Gran Turismo the VALVETRONIC functions have been optimised again by a new adjuster complete with a fully integrated sensor serving above all to make the adjustment process even faster than before. Indeed, the inertia factor on the new adjuster is only one-tenth the figure on the former model, serving to further improve engine response. Responding smoothly, directly and immediately to the gas pedal, the new straight-six is clearly the leader in its class also in this discipline. Maximum torque of 400 Newton-metres/295 lb-ft, for example, comes at just 1,200 rpm.
Apart from the optimised VALVETRONIC control unit, the newly developed turbocharger also contributes to this superiority, ensuring a particularly spontaneous build-up of power since the ducts of three cylinders at a time are separated from one another both in the exhaust manifold and the turbocharger.
In practice, this means particularly low exhaust gas counter-pressure at low engine speeds, the double ducts then enabling the fl ow of gas to build up greater dynamism in the exhaust manifold and powerfully drive the turbocharger blades even at low engine speeds. Twin-scroll technology thus combines the benefits of two turbochargers within one system. And now this principle adapted to the BMW straight-six with its high standard of technology marks the ongoing, consistent development of BMW’s turbocharged engines.

High Precision Injection with new injector nozzles.
The VALVETRONIC system is fully integrated in the cylinder head. This intelligent and extremely compact arrangement allows a direct combination with High Precision Injection with its injection nozzles placed in the middle between the valves and, therefore, in the immediate vicinity of the spark plug in the cylinder head.
High Precision Injection in the new six-cylinder delivers fuel through innovative multi-hole valves at an injection pressure increased once again in large areas all the way to 200 bar. This ensures extremely precise dosage if the fuel injected as well as a particularly clean combustion process. And last but not least in this context, the direct injection of fuel serves to cool the fuel/air mixture and increase the compression ratio to a higher level than in a turbocharged engine with manifold injection – an advantage contributing once again to the greater power of the straight-six.
Displacing 2,979 cc, the new power unit delivers maximum output of 225 kW/306 hp. It therefore offers all the torque and muscle of a significantly
larger eight-cylinder, but comes with much lower weight and significantly lower fuel consumption and emissions. It is indeed far lighter than a comparably powerful eight-cylinder and remains even 4 kilos lighter than the straight-six turbocharged engine already well-established in the market.
The BMW 535i Gran Turismo accelerates from a standstill to 100 km/h in 6.3 seconds and reaches an electronically limited top speed of 250 km/h or 155 mph. The unusually good balance of performance and fuel consumption is clearly expressed by average fuel consumption in the combined EU cycle of just 8.9 litres/100 kilometres, equal to 31.7 mpg imp. And the CO2 rating of the BMW 535i Gran Turismo is just 209 grams per kilometre.
The BMW 535i Gran Turismo, like the other two model variants, comes as standard with a wide range of BMW Eff cientDynamics technology. Supplementing the excellent effi ciency of the respective engine and the eight-speed automatic transmission, features such as Brake Energy regeneration, on-demand management and operation of ancillary units including the electrical coolant pump, the electrical power assistance pump and the detachable a/c compressor, as well as consistent lightweight engineering, optimised aerodynamics including active management of air flaps, and tyres with reduced roll resistance, ensure optimum fuel economy and emission management at all times.

The power unit of the BMW 535i Gran Turismo is the fi rst turbocharged engine to feature a map-controlled oil pump which, taking up less energy, makes a further contribution to motoring effi ciency. Yet a further point is that the new straight-six power unit with turbocharger, High Precision Injection and VALVETRONIC, does not require sulphur-free fuel and may therefore be used without problems the world over. The final point is that the engine naturally fulfils both the EU5 emission standard in Europe and the ULEV II standard in the USA.

29 responses to “The latest BMW engine: N55 – found in the BMW 5 Series GT”

  1. tk says:

    negative. the turbo used in the N55 is made my borgwarner (you’ll have to look at the high-res press images to see the logo).

    the turbos used in the 4.4 twin-turbo (anyone know the encode for this thing?) is made by garrett.

  2. mb81 says:

    the engine is not similar to the one of X5/X6, but to the one of the new V12 in 7series. It uses a single twin scroll turbocharger, too.

  3. Joe says:

    How long do you think until we see this engine in the 335i?

  4. Blog Auto says:

    you can find the picture of the N55 if i’m correct :

  5. Blog Auto says:

    @Horatiu B.: its from the 5 series GT press release, the engine in the pictures is the L6.. :=)

  6. Shawn says:

    Incredible! Place this engine in the new 135Tii or 335Tii with their respective low weight and I will sign my name on the dotted line. If the massive 4000 lb + 5 GT can average nearly 32 mpg – imagine the performance and efficiency of the engine in a much lighter car (1000+ lb lighter!!!).

    Once again BMW’s dominance in engine technology leads the way. Bravo.

  7. steven says:

    so are there 1 or 2 turbos in the new 760. i just assumed there were 2, but a quick search makes me think 1, based on the fact that they used the term “twinpower” there too…

    just curious…

  8. Carlos Perez says:

    Isn’t supposed that the N54 was going to recibe an actualization to generate 326 hp?? because if so, it doesn’t make much sense to offer this engine with less hp that the N54.

    And same question here, this engine qualifies as a turbo, twin turbo, or supercharged engine?? (The last one is the least probable, but just in case, i’m no to relationated with the turbos topic)

  9. Doug says:

    If a single twin-scroll turbo is equivalent to the twin/sequential turbos in the N54, why did they use twin turbos to begin with? Twin scrolls aren’t that new. Why are they using twin turbos in the 4.4 if one will do? It just adds complexity to the plumbing and engine tuning.

    I understood that the benefit of these turbos was not so much that they’re twin-scroll, but that they have variable geometry (do they?) and can force faster spinup with less exhaust pressure.

  10. Horatiu B. says:

    @Doug: Let me find out tomorrow if we can get the right person to answer this question. I’ll send the question to the right people and see what we can get :)

  11. tk says:

    @Doug: good question. i’d like to know the answer also.

    but i do know that they don’t have variable vane geometry like the 997 porsche turbo’s turbos. low-rpm boost is accomplished through the trick exhaust manifold and twin-scroll turbos.

  12. Doug says:

    Horatiu — would be really interesting to hear what they say! Who are these “right people”? :)

    @tk: Honestly, I thought I’d read of at least one BMW that used it, so assumed they were moving to that.

    What’s this trick exhaust manifold you speak of?

    Another possibility is that each scroll is shaped so as to provide different benefits.

  13. tk says:


    i can’t find a pic of the exhaust manifold for the N55, but i’m sure it’s similar to the one from the X5/6 M engine above (seriously, anyone know the engine code for this thing?). obviously, the N55’s would have 3 cylinders feed each of the inlets, instead of 2 on the X5/6 M engine.

    not exactly ‘trick’ per se – just a necessary design to make the twin scroll turbos work.

  14. Doug says:

    @tk: Great diagram! Although, it was baffling at first because it looked like the turbos were on backwards. That choice in routing particular cylinders in both banks to particular scrolls is interesting, it must have to do with the firing order?

    In the link below, there’s good pictures of the 4.4L and fantastic commentary from readers regarding the engineering decisions. The article mentions that variable geometry is very expensive, and BMW is using very simple turbochargers, benefitting from short exhaust and intake length (thanks to air-water intercoolers) that minimize compressible volume and thus turbo lag. There’s no explanation for twin-versus-single turbos, though.

    I wonder if they’ll move to water intercooling on the N55, and how the performance segmentation will work (eg, NA -> T -> TT).

  15. pandamalone says:

    Honestly I am disappointed BMW replace the two small turbochargers with one single twin-scroll turbocharger. It’ll definitely cut cost and weight, but performance-wise a single twin-scroll charger is still not as good. Not to say the twin-turbo has better potential for tune-ups. The introduction of valvetronic is good, however it won’t help as significantly as it did in the N52 which is still port injection and whose engine load is solely controlled by the amount of air-fuel mix into the cylinder. Engine response toward sudden fuel paddle kick-downs will be better, thou, with valvetronic. It provides a solution to kill dead volume in the intake manifolds, similar to the one-throttle-per-cylinder design in the E46 M3’s S54B32 but cheaper.

  16. swifty says:

    One of the main reason they are doing this is to differentiate between the future M engines and the regular ones…all future M ones (as well as special ones) are going to be twin turbos and the regular ones are eventually going to be single (twin scroll) turbos…

  17. vinod kumar says:

    very interesting……………..

  18. k.pravien says:

    i think it is good designed engine model,why because usage of fuel consumption is low when compared to other car.

  19. Daming Liu says:

    It is a good design combining the GDI, Valvetronic and Turbocharger together. While I want to know the how to treat the emissions of the engine and the engine uses stratified-charge lean burn combustion or homogeneous-charge stoichiometric combustion.
    Thanks a lot!

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