In this entry, I will express my subjective opinion regarding the progress of the BMW petrol engines during the last couple of decades. I already insistently warn – this material can not be recognized as the reference, because I will mention (in my opinion) the most exciting aspects. Part of the engine, part of the solutions, will stay “behind the curtain.” Mostly I will mention the 6-cylinder engines because they are the “most popular” ones in the BMW engine family, and, as it looks, all innovations first are introduced precisely in these engines.
We live in a unique time of unprecedented opportunities. I started my acquaintance with BMW when M10/M20/M30 series engines were popular. Now we see i3 and i8 rolling the streets. Modern vehicles have B38, B48, and B58 series engines. We see the rise, decline, and transition of petrol internal combustion engines to electric generation.
My experience with BMW engines started with the M20B23/B25 series. Already at that time, BMW was a step ahead of others. In the middle of 80-ties, LE Jetronic was replaced by the modern Motronic 1.1, later 1.3.
The difference between these DME management systems – in the newest version, the Lambda probe for the control of the fuel mixture was already intended. The implementation of these management systems happened at an unprecedented pace. For a short moment, Motronic 1.0 was installed on 7er E23, then 1.0 adaptive: 6er E24, M30 series engines already after a little while the technology (ver. 1.1 and 1.3) was implemented in 3er E30 series and 5er E28.
With the introduction of M50 engines in the last years of 5er E34 and 3er E36, everyone was surprised. The engine had a very modern appearance and excellent technical parameters for that time. BMW introduced the anemometric air mass meter; individually adjusted fuel injection in each cylinder. The actual Bosch management systems: Motronic 3.1 and 3.3.
It did not have to wait long on M50TU, which was named M52 shortly after. In this engine, inlet VANOS was introduced, also the electric throttle, separate Lambda probe for each bank of the engine. For a short moment, both Bosch and Siemens management systems were functioning side by side, but slowly the relay was handed over to Siemens. Several years later, M52TU, which was after named as M54, was implemented with exhaust VANOS, control probes behind the CO catalytic converters.
At this moment, BMW switches the supplier of DME, and the cars are assembled with Siemens management systems: the legendary MS41/42/43.
In the engine cooling systems, manageable thermostats are used, in addition to the viscous fan coupling electrical fans are introduced (initially – with 3 fixed speeds, later – manageable by PWM).
M3 series in E46 body gets a legendary S54 engine, which is managed by MS45 DME. This atmospheric engine develops 340hp (which is above 100hp/one liter) – a very impressive parameter for a serial car of those times. Users could choose the manual gearbox or the SMG 2 robotized gearbox.
N series of BMW engines marks a new development leap.
For six-cylinder engines (and most of 4 cylinder engines also), Valvetronic (valve lift adjustment system) was introduced. Exception: N43/N53 series engines, which get the unique Stratified charge. Valvetronic ensures a fuel economy of around 15%. In all N series engines, wideband Lambda probes LSU 4.9 were implemented as the main probes – the newest Bosch product of that time. The depression in the inlet manifold is measured by the differential pressure sensor, which ensures a more swift reaction of the engine to the accelerator pedal. In the inlet manifolds, the DISA system appears (in the most powerful versions of the engines) – the management system of the air intake channel length, which ensures even torque in an extensive range of RPM. The exhaust systems of the engines are equipped with the EGR system – it allows us to save fuel, reach the working temperature quicker and maintain it more effortless. The engines are equipped with the oil pumps of high flowrate; oil pressure is adjusted by DME. With N52N series engines, electronically manageable water pumps are introduced. Valvetronic also gets the second generation – more accurate, more compact, with less impact of the wear of spare parts. The atmospheric engines reach the power limit of 100 hp/one liter – both N52N in its powerful version (installed on X3/X5: E83/E70, E6X, E9X 330i/iX series vehicles) and N53B30O0 engine, which uses a Stratified charge.
N43/N53 series engines are the most complicated, but at the same time – also the engines, which give the best driving pleasure in the BMW history. 100hp/liter, excellent fuel economy, the lightning-fast reaction on the accelerator pedal – the characteristic features of these engines. Yes, these engines do not have Valvetronic, but for the first time in the BMW development history, the DI principle is introduced; HPFP, which develops a pressure of 150 .. 200 Bar. For the first time, piezo injectors are introduced. For the first time, the unique Stratified charge fuel injection system of BMW was introduced. To fight the increased amount of the nitrite exhausts, the exhaust systems are equipped with a Trap type NOx catalytic converters; the NOx sensors control their performance.
Siemens DME manages N52/N53 series engines: starting with MSV70, then: MSV80; in MSD80, the management of piezo injectors is introduced.
M5 in the E60 body gets an S85 engine. Yes, it doesn’t have nor HPFP, not other over-modern technologies, but the performance of ist 10 cylinders leaves no one indifferent!
M3 and M5 series vehicles can be bought with a manual gearbox or SMG 3rd generation robotic gearboxes. The 8-cylinder engine family gets an N63 series engine, which has two HPFP, piezo injectors, and two turbochargers. The most powerful versions of this engine – S63 – are installed in the “analogs” of M-type even till the F series.
N53 series engines with MSD87 (and using Stratified charge) are still used in F10/F11 preLCI versions.
This moment I consider the highest point of the progress of the BMW engines.
Since that moment, the progress of the BMW engines is not just stopping. At that moment, the thorough regress starts.
On the basis of the N53 series, N54 series engines are produced, basically for the USA market (Stratified charge engines were not sold in this region due to the low fuel quality). They don’t use a Stratified charge, but they do have two turbochargers.
N55. This engine uses equal block as N53 and N54, but instead of piezo injectors – the new generation of “regular” injectors is used. They should be safer, and probably – cheaper in the manufacture (true thou, the price in the retail does not indicates it). Instead of two turbochargers (which work in the “pulse” mode) now is one low-pressure turbine implemented. Just one instead of two main probes – only logical. Instead of Siemens DME – Bosch (re)starts its victory move.
The era of the atmospheric engines in the Motorsport division vehicles is over. Both – M3 and M5 – get turbo engines, SMG gearboxes are not available anymore for M5. For F10 generation, the manual gearbox is available by particular order if the car is for the USA market.
M5 F90 already has an all-wheel drive and automatic gearbox. Now the start is controlled by DSC, Launch Control systems. Yes, the start times till 100km/h are more than impressive (around 3.4 seconds), but now nothing is defined by the pilot’s skills. The only thing which he has to do – press the right buttons and the accelerator pedal.
B58. For these 6-cylinder engines, the HPFP, similar to the one used in N43 (4 cylinder engine), is now used – obviously, somehow is managed to “squeeze out” the required flowrate and pressure. The pump has one plunger, not three as for N53/N54/N55, but – without any doubt: it is cheaper in manufacture. A twin-scroll turbine is used (this technology is several decades old); instead of the electrically manageable thermostat – electrically manageable valve. Instead of powerful electrical cooling pomp – old-type mechanical. The vacuum pump also is mechanical. VANOS became more compact – management valves integrated into the VANOS mechanism itself, but otherwise – nothing new. Valvetronic became more compact – the “old” parts placed differently, not changing their functionality. The new “regular” injectors, as it turns out, don’t give less trouble than the capricious, cursed piezo injectors. In their materials, BMW puts an accent on the electrical wastegate – but this technology already has a history of several decades!
Yes, the torque of the engine is as if it increased, compared to N55. From 400 to 450 Nm. Significantly increased? In my opinion – no. It is not a significant increase. BMW has started the new concept, in which it uses “constructor” combined with the diesel engine? Yes, they do. But that is an economy in the inside of the BMW AG! We, buyers of the BMW vehicles, in no way, feel this economy, because each next model gets even more and more expensive.
My opinion is harsh – the regress of the BMW petrol engines during the last decade is a catastrophe. If still in the Year 2010, BMW had a significant surge form others, then at this moment – I feel shame for the newest petrol engines of this manufacturer.
At the end of a short remark, why and how does the BMW manage to make their already technologically weak engines to make “driveable” not taking into account the turbo lag and very significant loss of the torque in the upper range of RPM? The answer is – gearbox! The ZF 8HP gearboxes are an excellent product! Finally, in Sport and Sport+ modes, there is no sensation that the gearbox is slow in switching. The algorithms of the gearbox’s performance at the moment of start are radically changed, using Launch Control. These gearboxes save the average engines. For example, if Launch control is used, the F90 M5 vehicle reduces start time till 100km/h for more than a second! BMW has won the fight for the tenths of the second, but the driving pleasure, which is given by BMW, has stayed in the second place. Yes, possibly, I am old in my beliefs and feelings. It is possible that nowadays BMW driver does not want to know anything about driving trajectories, driving of curves, car handling. It looks that it is so because the profit indicators of BMW show records from quarter to quarter – it is a confirmation that they manufacture the “right” cars…