BMW’s first-ever inline-six-cylinder engine, designated because the M78, was produced from 1933 to 1950. The preliminary model, the 303, featured a 5.6:1 compression ratio, a 56mm cylinder bore, and an 80mm stroke, leading to roughly 29 horsepower and 68 Nm of torque. Although it could not sound like a lot in right this moment’s world, it marked the start of a brand new period for BMW.

The N54 Engine: BMW’s First Mass-Produced Turbocharged Gasoline Engine

In 2006, BMW launched the N54 engine, the successor to the naturally aspirated inline-six-cylinder N52 engine, and boy, did it dwell as much as its hype. The N54B30O0 grew to become BMW’s first mass-produced turbocharged gasoline engine in over 30 years. A enjoyable truth: BMW unveiled their first-ever turbocharged car, the 2002 turbo fitted with the M10 engine, again in 1973, igniting the turbocharger craze that continues right this moment.

The N55 Engine: The N54’s Successor

In 2009, BMW revealed the N55 engine, succeeding the N54 and internally designated as N55B30M0. The principle distinction between the N54 and N55 engines was the usage of two exhaust turbochargers (bi-turbo know-how) on the N54 and a single twin-scroll exhaust turbocharger on the N55. The N54 additionally utilized a vacuum-controlled blow-off valve and wastegate, whereas the N55 used an electrical blow-off valve with a vacuum-controlled wastegate till June 2013 when it was switched to an electronically managed wastegate. These engines share many similarities, with diminished prices and improved high quality being the primary distinguishing components.

The Variations Between the N54 and N55 Engines

The N54B30O0 and N55B30M0 possess nearly the identical technical information: roughly 300 horsepower, 400 Nm of torque, 1-5-3-6-2-4 firing order, direct cost air cooler, 3-piston high-pressure gas pump able to reaching system pressures of as much as 200 bar/2,900 psi, Double-VANOS, electrical coolant pump, aluminum crankcase, 10.2:1 compression ratio, 89.6mm stroke/84mm cylinder bores, 24-valve inline six-cylinder, 2-stage vacuum pump, 82.5mm full slipper skirt pistons, and an open-deck engine block design, to call a couple of. The tuning potential of those engines is insane, by the best way; with full bolt-ons, they’re confirmed to supply effectively over 800+ horsepower – signal me up.

The Tuning Potential of the N54 and N55 Engines

The variations between the N54 and N55 are simply as fascinating as their similarities and their potential for a large energy enhance. The N54 used a gas injection system referred to as BMW HPI or Excessive Precision Injection with Piezoelectric Gasoline Injectors. BMW switched to a more recent gas injection system with the N55 known as BMW HDE or Excessive-Strain Gasoline Injection with Bosch Solenoid Valve Gasoline Injectors with CVO assist. Unbeknownst to many, the N54 didn’t have BMW’s coveted Valvetronic. This was launched for the primary time in a turbocharged BMW engine on the N55 and utilized BMW’s Valvetronic III system with a small, but very highly effective, brushless DC servomotor.

The Efficiency of the N54 and N55 Engines

The N54 was utilized in autos such because the 135i (E82/E88), 335i (E90/E92/E93), Z4 sDrive35is (E89), and even the X6 xDrive35i (E71), to call a couple of. The BMW 1M Coupe acquired a modified model of the identical engine, designated N54B30T0, which produced roughly 340 horsepower and 450 Nm of torque with an extra 50+ Nm overboost operate. Fairly good figures for a car that weighs 3,200 lbs. The 1M’s additionally maintain their worth extraordinarily effectively and are tremendous uncommon – try our article about what Dinan can do to those spectacular little machines for a few bucks.

The N55 was utilized in autos such because the 535i (F10), M235i (F22), X3 xDrive35i (F25), and the X5 xDrive35i (F15), amongst others. The M2 (F87) additionally acquired a souped-up model of the N55, designated N55B30T0 – if you happen to opted for the competitors bundle, you acquired the S55B30T0 with roughly 400+ horsepower. The N55 additionally utilized a brand new DME designated MEVD17.2; the predecessor used on the N54 was designated MSD80 & MSD81 – which included the addition of FlexRay.

Along with Valvetronic being launched on the N55, the valve practice specs additionally modified barely. Consumption valve elevate was elevated from 245 levels on the N54 to 255 levels on the N55, in addition to the diameter of the consumption valves being elevated from 31.4mm to 32mm. Consumption VANOS adjustment vary elevated from 54 levels on the N54 to 70 levels on the N55. The exhaust VANOS adjustment vary elevated from 45 levels on the N54 to 55 levels on the N55. The camshaft length of the N55 can also be bigger than its predecessor. The N54 cyclone separators for crankcase air flow had been deleted within the N55, primarily as a result of utilization of latest VANOS solenoid valves. The N54 had way more advanced oil passages in comparison with the N55, and the oil pump was lubricated by unfiltered engine oil, whereas the N55 oil pump was lubricated by filtered engine oil.

Talking of oil pumps, the N55 makes use of a modified model of the N54’s characteristic-map volume-flow managed pendulum slide cell oil pump and for the primary time, included a duroplast reciprocating slide. Coolant ducts within the cylinder head of the N55 are additionally used for oblique gas injector and valve cooling. The harmonic balancer was additionally optimized with the belt pulley sitting on the secondary disc, in comparison with the N54’s design – this diminished further belt load because the belt pulley with flywheel mass is decoupled from the crankshaft by vulcanization. Solely light-weight camshafts are used on the N55 versus the N54, which used both forged or light-weight development camshafts or a mix of each. Crankshaft weight was additionally diminished by roughly 6 lbs – N54 & N55 engines each use cast-iron crankshafts.

The Reliability of the N54 and N55 Engines

In the long run, the N55 is the extra dependable choice as a result of refinements and alterations BMW made. It won’t have the tuning potential of the N54, or the sound notes, nevertheless it’s a workhorse of an engine that appears to have much less reliability points.