BMW N54

Models

As per the 3.0 litre version of the naturally aspirated BMW M54, all models have a bore of 84 mm (3.3 in), a stroke of 96 mm (3.8 in), a capacity of 2,979 cc (181.8 cu in) and a compression ratio of 10.2:1.

N54B30 (225 kW version)

For the E90/E91/E92/E93 3-Series, the N54 engine was used in the 335i model from 2007 onwards. In the 3-series, it therefore replaced the 330i (which used the naturally aspirated N52B30 as the performance model below the M3).

This version is rated at 225 kW (302 hp) and 400 N·m. However, independent testing has resulted in estimates of 332 hp (248 kW) and 311 lb·ft/422 N·m.

Applications:

N54B30 (240 kW version)

A variant of the N54B30 with higher power and torque (but a slight reduction in low rpm torque) is used in the F01 740i and E92 335is.

Applications:

N54B30TO (250 kW version)

The most powerful version of the N54 is found in the E89 Z4 sDrive 35is (as of 2016, the only application of the N54 still in production) and the 1 Series M Coupe.

Applications:

Design

Unlike the (naturally aspirated) N52, N53 and (turbocharged) N55, the N54 does not use variable valve lift (called valvetronic by BMW) or a magnesium alloy block. This is because the newer N52 aluminum-magnesium engine block was not deemed as suitable for turbo-charging with the above-mentioned engineering goals. Instead, the N54 engine is based on the older BMW M54 engine. It therefore features an aluminium construction and variable valve timing to both camshafts (called dual VANOS by BMW). Differences between the M54 and N54 include twin turbochargers, an intercooler, direct injection, a closed-deck single-piece block and an electric water pump. As per the M54B30, the N54 has a capacity of 2,979 cc (182 cu in). With a weight of 195 kg (430 lb), the N54 is 34 kg (75 lb) heavier than the N52.

The engine uses two small low-pressure turbochargers to minimise turbo lag. The boost pressure is 8.8 psi, because BMW's goal was to offer the same driving feel as with naturally aspirated engines. BMW's term for turbocharging is "TwinPower Turbo", which has also been applied to the N55, which uses a single turbo (but with twin-entry turbine housing).

The engine's direct injection system uses piezo injectors, as per the naturally-aspirated N53. The N55 engine uses solenoid-type injectors, because the piezo injectors are more expensive and not reaching their full potential to obtain the "lean burn" benefit. BMW's trademark for direct injection, regardless of type, is known as "High Precision Injection".

Performance

Compared with its naturally aspirated N52 predecessor, turbocharged N54 produces an additional 45 hp (34 kW) and 80 lb·ft (108 N·m). The N54's power delivery was described by Car & Driver as lag-free and similar to a 4.4 litre V8.

The N54's replacement, the N55 3.0L turbo inline-6 uses a single twin-scroll turbocharger instead of the twin-turbo setup used by the N54. Initial versions of the N55 produced the same peak power and torque (although peak torque is 200 rpm earlier). Initial versions of the N55 were less powerful than the high-output versions of the N54 (such as used in the F01 2009 BMW 740i), however these outputs were eclipsed in 2013 when more powerful versions of the N55 became available.

In the E60 5 Series, the 4.8 litre V8 model was judged have more nose-heavy handling than the N54-powered 535i, and the acceleration was deemed to be only marginally faster. In the F01 7 Series range, the handling of the N54-powered 740i was preferred over the 750i (powered by a 4.4 litre twin-turbo V8 model), although the acceleration of the 750i was faster. Another reviewer found the N54-powered 7 Series model to have more linear power delivery than the 4.4 litre twin-turbo V8 model. Fuel economy of the 740i is comparable to the ActiveHybrid 7, however the ActiveHybrid 7 accelerates to 60 mph (97 km/h) 1.1 seconds quicker than the 740i.

HPFP Failure

In at least the US market, the N54 engine has been characterized by a very large number of High Pressure Fuel Pump (HPFP) failures, leading to BMW North America vehicle Lemon Law "buy backs" and reduced customer goodwill. BMW's failure to solve the HPFP problem has led to serious safety concerns over dangerous sudden losses of power at highway speeds. Reports of drivers being stranded are not uncommon and some have accused BMW of actively concealing the problem rather than addressing it. On 26 October 2010, BMW announced a recall of vehicles with the pump in question from manufacturing years 2007–2010.

In April 2009, a class action suit was filed against BMW in connection with HPFP failures. BMW settled the suit in June 2010. On 26 October 2010, following an ABC News story about HPFP failures, BMW announced a recall of vehicles with the pump in question from manufacturing years 2007-2010.

Turbocharger Failure

The N54 turbochargers have been known in at least the U.S. and Canada to suffer from premature wastegate bushing wear which results in an audible wastegate rattle noise. If the wear is severe enough the wastegate will not seat properly resulting in a loss of boost pressure and trigger engine fault 30FF which temporarily reduces power output. BMW North America (which does not manage the Canadian market despite its name) recognized the design flaw and extended the warranty period for US vehicles to 8years/ 82,000 mi for wastegate related issues only. BMW Canada (which does manage the Canadian Market) does not offer any relief for turbocharger wastegate rattle issues in Canada beyond original warranty.

Valve Intake Build-Up

It has been widely reported that the N54 valve intakes experience build-up of oil and gas deposits (carbonizing). The build up of a black film on the intakes can, over time, cause reduced power and has been linked to misfiring,. Some N54 owners experiencing significant build-up have reported a perceived improvement in performance once the build-up is removed (although dyno charts of an unclean N54 vs a cleaned N54 have not been widely publicized).

The recommended method and frequency of cleaning varies, but most forums, which include feedback from experts and mechanics, recommend 'walnut media blasting' (for example, ). This is a process by which pressurized air (usually 6-8 bar) is combined with fine walnut shell granules and blasted into the intake tracts. These granules hit the build-up at high speed and remove it entirely. Walnut material is soft enough not to damage the metal of the intake tract and the valves.