| Manufacturer | BMW, Bayerische Motoren Werke AG |
|---|---|
| Production | 2006– |
| Predecessor | BMW M54, BMW N52 |
| Successor | BMW N55 |
| Class | Straight-6 |
The N54 is a direct injection twin-turbocharged straight-6 automobile engine from BMW.[1] It was launched in late 2006 as a high-performance option for the BMW 3-Series, first to be released along with the new 3-series E92 Coupé, to be followed closely by other existing 3-series models, then with other BMW series as well. It is BMW's first production turbocharged gasoline engine in 26 years since the 745i in 1980. The new engine debuted at the 2006 Geneva Motor Show and won the International Engine of the Year award in 2007 and 2008.
| Engine | Displacement | Power | Torque | Redline | Year | Note |
|---|---|---|---|---|---|---|
| N54B30 | 3.0 L (2979 cc/181 in³) | 190 kW (254 hp) @ 6600 | 310 N·m (230 ft·lbf) @ 2600 | 7000 rpm | 2009 | Naturally aspirated; Asian markets only |
| N54B30 | 3.0 L (2979 cc/181 in³) | 225 kW (306 hp) @ 5800 | 400 N·m (295 ft·lbf) @ 1400-5000 | 7000 rpm | 2006 | Twin Turbocharged |
| N54B30 | 3.0 L (2979 cc/181 in³) | 243 kW (370 hp) @ 5800[2] | 450 N·m (332 ft·lbf) @ 1500-4500 | 7000 rpm | 2008 | Twin Turbocharged |
| N54B30 | 3.0 L (2979 cc/181 in³) | 250 kW (335 hp) @ 5900 | 450 N·m (332 ft·lbf) @ 1500-4500 | 7000 rpm | 2010 | Twin Turbocharged |
The N54B30 does not use the second generation Valvetronic technology found in the naturally aspirated N52 and the newer (single) turbocharged straight-6 N55.
Surprisingly the engine block of the N54B30 is similar to the older generation BMW M54B30 engine - all aluminum with cast iron cylinder liners. This is because the newer N52 aluminum-magnesium engine block was not deemed as suitable for turbo-charging with the above-mentioned engineering goals. As a result, the N54B30 is physically heavier (195 kg (430 lb)) than the very light (161 kg (355 lb)) N52 engine. This also explains why the engine block size is identical to the older M54B30 at 2979 cc/181 in³ instead of the 2996 cc/182 in³ of the new N52B30 3.0L engine. There are some differences between the M54 and N54; the M54 is a single-piece block, with the water pump housing cast into the block, and is a closed-deck design, compared to the N54's two-piece block with a separate bedplate, electric water pump, and open deck.
According to BMW, the N54B30 produces 306 hp (228 kW) and 295 ft·lbf/400 N·m. Third party testing has revealed the engine is significantly underrated, producing 332 hp (248 kW) and 311 ft·lbf/422 N·m in one test.[3] The engine uses two small low-pressure turbochargers to remove turbo lag at low elevations. For this reason, the turbo pressure is only 8.8 psi as the engineering goal was to offer the same driving feel as with naturally aspirated engines.[4]
In the Asian-only F01 730i/Li variant, the twin turbochargers are removed leaving the engine to be naturally aspirated. [5]
The N54 has considerably higher horsepower and torque, compared to BMW's recent straight-6 engines which were all naturally aspirated such as the high output versions of the N52B30 (which has the same displacement as the N54), with the N54 having an additional 45 horsepower and 80 pound-feet of torque over the N52B30.[6]
The N54 gives similar acceleration to the high-reving 3.2L S54B32 which was based on the M54); the N54 has less horsepower but greater torque is available at a much lower rpm while consuming less fuel. In addition, while the S54 was an expensive engine limited to uses a BMW M model, the E46 BMW M3, the N54 is less costly to produce and has a wider range of application in BMW's lineup.[7][8]
The N54 has proven its superiority against larger displacement naturally aspirated 6-cylinder engines (citation needed), such as Infiniti's VQ37VHR 3.7 L V6 that has an output of 328 hp (245 kW) 269 ft·lbf (365 N·m). While the N54 has around 30 less horsepower than the VQ37VHR, the N54's horsepower and greater torque are available at much lower rpms. The N54 mated with a shorter gearing manual transmission and this combination gave the 2007 BMW 335i the advantage over a 2008 Infiniti G37 with a 0.3-second lead in 0-to-60 mph and quarter-mile times (5.1 and 13.7, respectively) with a 3.1-mph-higher trap-speed. The N54 is also a smoother and more efficient engine, as the 335i got 3.3 mpg more in fuel economy over the G37's 18.4 mpg.[9][10] The N54 also compared favorable to the Lexus 3.5L V6 (2GR-FSE) which has a top output of 305 hp and 278 ft·lbf, in a comparison between the 2007 BMW 335i and Lexus IS 350.[11]
BMW's newer N55 3.0L turbo inline-6 uses a single turbocharger but with twin scroll technology, and its 300 lb-ft of torque comes at 1200 rpm which is 200 revs earlier than the N54’s identical output.[12] The N55 is also more fuel-efficient and has less emissions than the N54. However, the N54 engine has more output potential and a variant of the N54B30 with higher power and torque but across a narrower peak torque band is used in the F01 2009 BMW 740i.[2][13] A comparison test saw the 2011 BMW 740i accelerate quicker than the 2011 BMW 535i (equipped with the N55), even though the 535i weighs 300 pounds less. [14]
A comparable 6-cylinder engine to the N54 in torque and horsepower is Audi's 3.0 TFSI (G60) supercharged V6 engine. The 2009 Audi A6 3.0T is a direct competitor to the 2009 BMW 535i,[15][16] as is the 2010 Audi S4 to the 2009 BMW 335i, and in both cases the N54 was able to deliver largely equivalent performance.[17]
The ample torque of the N54 engine combined with the lack of turbo lag provides the same feel as a small V8. The advantage of the N54B30 engine is that compared to similar power output 225 kW (302 hp) 290 lb·ft (390 N·m) V8 4.0L N62B40 it weighs 70 kg less than the V8, which is massive at 265 kg (584 lb). Additionally, the N54 has higher low-end torque than the N62. It is likely for these reasons BMW chose to develop bi-turbo inline straight-6 engines for the 3-series instead of using heavier V8 engines. In the 5 Series (E60), the N54 in the 2008 BMW 535i gives it almost equivalent acceleration to the BMW 550i, with a V8 engine (4.8L N62B48) which costs an additional $10,000 USD in MSRP and makes the front 200 pounds heavier (which dampens driving reflexes).[18]
Only the 2008 BMW M3 will have a V8 engine in the 3-Series lineup, weighing in at 202 kg (445 lb) and generating 414 hp (309 kW) and 295 lb·ft (400 N·m), however this V8 is derived from the V10 engine that powers the BMW M5. Nonetheless the tuned version of the N54, which is found in the 2011 BMW 335is, has higher low-end torque than the M3's V8 engine, 332 pound-feet at 1500 rpm for the 335is versus 295 pound-feet at 3900 rpm for the M3, and the V8's higher maximum horsepower of 414 hp (309 kW) is only available at 8300 rpm. [19]
In the 2011 BMW 740i, the N54 is down 85 hp (63 kW) and 120 lb·ft (160 N·m) compared to the 750i’s N63 4.4L twin-turbo V8, however the 740i weighs about 215 pounds (98 kg) less, which considerably improves handling dynamics.[20] The 740i also retains respectable straight-line acceleration in a comparison test as it could make the 0 to 60 mph (97 km/h) run in 5.1 seconds compared to the 750i's 5.2, and the 750i only catches up at 70 mph (110 km/h), with the N54 having less turbo lag and smoother acceleration than the N63. Fuel economy of the 740i is 17 mpg city and 25 highway, compared with the 750i’s 15/22 and the ActiveHybrid 7's 17/26, considering that the 740i has an MSRP of $71,025 USD while the ActiveHybrid 7 starts at $103,125 USD.[21]
The N54 has been found in every BMW nameplate
For the 3 Series, the N54 engine powered the 335i high-end configuration from the 2007 model year onwards, replacing the 330i and its 3.0L naturally aspirated straight-6 as the top model (aside from the BMW M3).
For the 5 Series, the N54 engine powered the 535i midrange configuration from the 2008 model year onwards, replacing the 530i and its 3.0L naturally aspirated straight-6 as in that segment. The top model (aside from the BMW M5) was already renamed from 545i to 550i for 2006 as it saw an increase in its V8 engine output from 4.4L to 4.8L.
The eventual successor N55 retains the N54's horsepower and torque, while improving emissions and packaging and reducing fuel consumption, so it has replaced the N54 in many applications as well as supplanting the high output versions of the N52B30. However, the N54 engine has more output potential and is easily modified with aftermarket tuning to produce in excess of 400 hp (298 kW). A version of the N54B30 with higher power and torque but across a narrower peak torque band was introduced in the F01 2009 BMW 740i.[2][22] While the 2011 BMW 335i sedans and the face-lifted 2011 BMW 335i coupes will be offered with the N55, the N54 will be retained in the higher-performing 335is. [23][24]
Most N54 engines are mated to a 6-speed manual transmission, while the 6-speed automatic with Steptronic is optional. However, the 2009 BMW Z4 sDrive35is and the 2011 BMW 335is have either a 6-speed manual or optional 7-speed dual clutch transmission.
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 many BMW NA vehicle Lemon Law "buy backs" and reduced customer goodwill. On some engines the HPFP was replaced four times within the first few years of service. BMW has instituted a 10-year, 120,000-mile (190,000 km) warranty on the part, but only for 2007, 2008 and 2009 model year vehicles with the N54 engine. Other model years, to include 2009 models, continue to report HPFP failures.[16] As of late 2009, the low pressure fuel sensor has become suspected of causing some premature failures of the HPFP by engine tuners such as AMS and CP-E.
BMW tried to engineer a newer HPFP solution to eliminate HPFP issues users were having. The first 335/135s came out with 1351 7 537 320 HPFP followed shortly by 1351 7 585 655 HPFP and 2009 model had 1351 7 592 881 HPFP followed by 1351 7 596 123 HPFP. These pumps were updated and replaced again due to the high rate of failure with 1351 7 594 943 HPFP. But these also started to fail and got updated and replaced in May 2010 with a brand-new re-manufactured pump 1351 7 613 933 HPFP.[25] On the 26th of October, 2010, immediately following an ABC News story about HPFP failures,[26] BMW announced a recall of vehicles with the pump in question from manufacturing years 2007-2010.[27] A class action suit has been filed against BMW regarding these problems. [17]