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BMW N55, an inline-six petrol engine, started to be produced in 2009 as a substitution for BMW N54 and was applied for F07 5 Series Gran Turismo.
Being the first brand’s motor featuring a twin-scroll turbocharger, it was called the best engine for three consecutive years, in 2011-2013, according to Ward.
Its production started to phase out since the release of BMW B58 motor in 2015.
BMW S55 is a high-productive variation of N55, employed for F80 M3, F82 M4 plus F87 M2 Competition.
BMW N55B30 is an example of contemporary workable technical excellence of gasoline motor output and economy. Being an up-to-the-minute power station, it’s applied for BMW 535i GT and soon will be employed for 535i model. Moreover, there is a possibility that N55B30 will later serve as a substitution for N54B30 in all BMW vehicles.
Being planned to serve as an alternative for N54B30, N53B30 and N62B40, this one is another sample of the new generation six-cylinder motors. Keeping the same aluminum cylinder block with cast iron sleeves featuring oil injectors as N54, N55 is provided with the lighter crankshaft. Actually, it weighs 20.3 kg and it’s 3 kg lighter than its predecessor. Pistons along with connecting rods, which are 144.35 mm long, were restyled.
The cylinder block was also redesigned as well as double-VANOS variable valve timing on the intake and exhaust shafts system. Among the additions is the variable valve lift system Valvetronic III. Intake valves have 32 mm diameter while the exhaust ones are 28 mm. The camshafts have duration of 255/261 degrees and lift 9.9/9.7 mm.
Additionally, inlet and outlet systems were modernized.
Twin scroll turbocharger replaced the twin-turbo configuration. As a result, the new Borg Warner B03 turbocharger features 2 exhaust gas inlets and 2 impellers. A turbocharger of such a kind may give the motor a boost more quickly and provide it with the maximal redline beginning from 1,200 rpm. Boost pressure equals 0.65 bars/9.5 psi.
Bosch MEVD172 control unit substituted the old one.
Meanwhile, N55 served as a framework for the building of the S55 sports motor, which was created by the brand for M3 and M4 sports automobiles.
|Also called||BMW N55|
|Cylinder block alloy||Aluminum|
4 valves per cylinder
|Piston stroke, mm (inch)||89.6 (3.53)|
|Cylinder bore, mm (inch)||84 (3.3)|
|Displacement||2979 cc (181.8 cu in)|
|Power output||225 kW (306 HP) at 5,800-6,000 rpm
235 kW (320 HP) at 5,800-6,000 rpm
240 kW (326 HP) at 5,800-6,000 rpm
250 kW (340 HP) at 5,800-6,000 rpm
|Torque output||400 Nm (295 lb·ft) at 1,200-5,000 rpm
450 Nm (332 lb·ft) at 1,300-4,500 rpm
450 Nm (332 lb·ft) at 1,300-4,500 rpm
450 Nm (332 lb·ft) at 1,300-4,500 rpm
|HP per liter||102.7
|Weight, kg (lbs)||~132 (290)|
|Fuel consumption, L/100 km (mpg)
|for E92 335i
Borg Warner B03 Twin Scroll
|Oil consumption, L/1000 km
(qt. per miles)
|up to 0.7
(1 qt. per 850 miles)
|Recommended engine oil||5W-30
|Engine oil capacity, L (qt.)||6.5 (6.9)|
|Oil change interval, km (miles)||7,000-10,000
|Normal engine operating temperature, °C (F)||~110 (230)|
|Engine lifespan, km (miles)
-No life span loss
- BMW 135i E82/E88
- BMW M135i F20
- BMW M235i F22/F23
- BMW 335i E90/E91/E92/E93
- BMW 335i F30/F31
- BMW 435i F32/F33/F36
- BMW 535i F10/F11
- BMW 640i F12/F13
- BMW 740i F01
- BMW X1 E84
- BMW X3 F25
- BMW X4 F26
- BMW X5 E70
- BMW X5 F15
- BMW X6 E71
- BMW X6 F16
- BMW 335 GT F34
- BMW 535 GT F07
N55B30 engine problems and reliability
- Valve Cover or Valve Cover Seal Oil Leakage
Like N54, N55 often faces valve cover, valve cover seal and positive crankcase ventilation valve leakage. In the course of time, the rubber valve cover seal starts to destroy due to high temperatures plus continuous heating and cooling. Consequently, the seal spoils and leads to oil leakage along with the possible emergence of oil concentration in the motor.
- High temperatures also have a negative effect on the valve cover. As it’s made of plastic, some cracks may appear after constant exposure to the too hot ambiance. This problem emerges more seldom than the previous one and usually happens after 100, 000 miles are run. Though, as it’s pretty hard to reach the valve cover seal, it’s highly advisable to substitute the valve cover as well to avoid problems in the future. Any time you take away the valve cover, the valve cover seal must be replaced.
Additionally, the positive crankcase ventilation valve, which is integrated into the valve cover, may be subjected to leaks. It employs the motor vacuum to draw blow-by gases out of the crankcase. The high pressure and weariness of this element cause its malfunction. In order to replace the PCV valve, you’ll need to take away the valve cover and valve cover seal. So, it’s reasonable to replace everything in one approach.
- Failure of the Water Pump
Troubles with water pumps are rather widespread among BMW motors. Pumps distribute coolant throughout the cooling system to decrease the motor temperature. BMW employs electric pumps, controlled by an unreliable composite impeller. The other reason for this problem is the thermostat malfunction. It’s rather hard to change the old water pump for the fresh one and so, it’s reasonable to substitute a thermostat as well. If to share our own experience with the N54 motor, featuring the same water pump, our 535i vehicle already has its third water pump.
The original one broke down after 52,000 miles while the second one started to function improperly after 84,000 miles. Other examples are when the water pump of the 135i car failed after 33,000 miles while the one at 335i lasted until 95,000 miles. You see, the lifespan of water pumps varies from 20,000 to more than 120,000 miles. Basically, if you have driven for more than 100,000 miles with the original pump and thermostat, be ready that they may fail soon.
As a rule, you can’t notice any minor malfunctions until the pump fails as it usually happens unexpectedly. In case you notice that the pump is gradually failing electrically, we advise examining the coolant flow in the cooling system as the failing pump doesn’t flow coolant efficiently.
- Oil Filter Housing Gasket Leakage
Oil Filter Housing Gasket is another blindside of N55 and you may face its degrading and oil leakage after driving a vehicle for some time. The leakage of this gasket seems to be a trifle, but, actually, the oil may get to the belt tensioner and drive belt and spoil them. In the long run, the belt will click or slip off the pulley, leading to the failure of other motor components. Or, it may even reach the crankshaft seal, causing severe troubles with the motor. Though, it happens rarely. We just shared this fact for you to be aware of all possible faults.The solution is to substitute the oil filter housing gasket. Clearly, it’s probable that belts may slip or break down because of some other reasons.
- VANOS Solenoid Halting
VANOS, a valve timing system, is applied on the BMW N55 motor in combination with Valvetronic. It regulates the timing of the intake and exhaust camshafts depending on motor speed and throttle opening. It serves to enhance idling and smooth the output. With the increasing motor speed, VANOS raises torque and fuel economy along with decreasing emissions.VANOS Solenoids function incessantly and so, they may halt because of weariness or being old. It’s possible that they may also get covered with oil, causing some trouble because of being too dirty. Moreover, note that the VANOS bolts for 2010-2012 N55 motors were recalled and were replaced for new ones. The bolts may become loose or break. Once the latter happens, they reach the motor oil pan and some repair expenses are inevitable.
- High-Pressure Fuel Pump Failure
A high-pressure fuel pump deals with pumping fuel from the gas tank to the fuel injectors, where it is diffused into the cylinders thanks to direct injection. Basically, its failure was a popular problem for the motors released in 2010 and early 2011 and almost every engine had a pump, which didn’t function properly. Though BMW tried to fix this problem many times, an efficient solution was found only in 2011. Thus, the multiple troubles with the high-pressure fuel pumps, which were pretty common for both N54 and early N55 motors, became not actual.
While the N54 motor was provided with a ten years extended guarantee for 120,000 miles for its high-pressure fuel pump, the one at N55B30 wasn’t given any warranty at all. A vast number of non-efficient high-pressure fuel pumps, mounted on the first N55 motors, failed and BMW had to substitute them with new ones, which were more advanced and high-productive. However, there are always some exceptions to rules. Thus, you may still meet motors with old pumps, which work properly. If to pay no attention to the above-discussed issues, N55B30 seems to be a good option. It’s rather durable and reliable. It may serve pretty long, providing your vehicle with outstanding power. Moreover, it’s a great basis for tuning. So, despite some faults, this engine is a reasonable money investment.
As we have already mentioned, N55 motors are a great basis for tuning, just like their N54 predecessors. For instance, by applying the BMS JB4 Stage 2 firmware update with downpipes, you are able to increase your motor’s output to 360 hp.
But you may not stop at this. A cold air intake, for instance, the one by Burger Motorsports, in conjunction with a performance exhaust system will increase the power to 380 hp. And basically, these upgrades suit N55 motors the most. They will enhance the vehicle’s performance with no damage to the motor durability, allowing your BMW automobile to run 0,25 miles in 11.8-11.9 seconds. Just to compare: the original N55 permits a car to cover 0.25 miles in 13.3-13.5 seconds. So, if you are a high-performance fan, these updates will be a great option for you.
Additionally, you are free to substitute turbochargers and acquire Methanol Injection Kit for increased output. You will have to spend a solid sum of money on that. However, the result will be 450 hp.