It is a fact that the last naturally-aspirated inline-six S54s was the highest output engine before the invasion of V8 motors on the market. Before the V8 era, inline-six was the thing and remained there for a long time, even competing against their bigger counterparts. It only shows that inline-six is capable of warranting the consumers the power they demanded and wanted, that they don’t need more cylinders to achieve higher ceiling outputs.
So today, we will talk about BMW’s S54 engine, which is marketed as the high-powered variant of the M54 engine. However, it is actually more of a BMW S50 evolution and shares only a few parts with its smaller brother, M54. S54s debuted in E46 M3 in 2000 and have been in productions up until 2008. BMW S54 won the best engine in the international competition of power units for their 3.0 to 4.0 Liter category in 2001 until 2006. They earned the best engine in this category, dominating the competition throughout that period. S54 also joined the elite company of Ward’s Ten Best Engine award of the same year. They happened to be replaced by S55 engines after the finalization of their design.
A little background about M54 is that they are naturally-aspirated straight-six petrol engine that was produced from 2000 to 2006. It is a replacement for the M5 engine. However, BMW phased out M54 engines since the arrival of the BMW N52 Engine in 2004. It won Ward’s Ten Best Engines in three consecutive years from 2001 to 2003.
Engine Specifications and Design:
- Production Run: 2000-2011
- Cylinder Head Material: Aluminum
- Cylinder Block Material: Cast iron
- Configuration: Straight-six
- Bore: 87mm
- Stroke: 91mm
- Valvetrain: Double VANOS 4 Valves per cylinder
- Displacement: 3.2 Liters
- Compression Ratio 11.5:1
- Weight: 328 lbs.
- Max HP: 355 hp
- Max torque: 273 lb-ft
BMW S54 Engine is akin to its predecessor, BMW S50 engine, than to its M54 root. Though M54s and S54s carry the same number, they don’t share much apart from a few parts. BMW S54’s engine block is made from cast iron, and its cylinder heads are made from Aluminum. A high-revving engine has a redline of 8,000RPM and much more productive compared to the previous BMW S52 engine.
In comparison with the BMW S50 engine, S54s engines are equipped with revised camshafts, also known as VANOS (Variable Valve Timing for BMW), on both intake and exhaust camshafts which enhances the engine’s responsiveness at different operating conditions. There is also an increase in the bore size to 87 mm and the compression ratio from 11.3 to 11.5, resulting in a 3,246 cc displacement. It uses an electronic throttle control (replacing mechanical linkage), and its bucket-style tappets were replaced by finger-follower valve actuation. To avoid oil deprivation during corners, BMW integrated S54 engines with scavenging oil pumps to manage lubrication which is also present on S50 engines but not on regular S50B30s. S54’s Engine Control Unit (ECU) is Siemens MSS 54. S54s has no direct successor, so BMW S65 V8 engines power the succeeding M3 generations.
Due to the emission regulations in some countries, such as Europe and the United States, power and torque outputs may vary. This can also affect the intake and exhaust layout due to the space limitations of the chassis. So BMW made two versions for S54s:
S54B32 and S54B32HP
S54B32 configuration is the core engine of the S54. Its less-powerful variant, S54B32US, was meant for American cars like the Z4 M Coupe / Roadster and M3 E46.
S54B32s also appear in 2000 – 2006 E46 M3 models, producing 338 hp at 7,900 RPM and 269 lb-ft at 4,900 RPM. The United States and Canada models produce 333 hp and 262 lb-ft.
In 2000 – 2002 BMW E36/E37 Z3 M Roadster, E36/E38 Coupe which produces 321 hp and 261 lb-ft – models for the United States and Canada produces 315 hp and 252 lb-ft
2002-2011 Wiesmann MF 3 Roadster that produces 338 hp and 269 lb-ft.
2006 – 2008 E85 Z4 M Roadster and E86 Z4 M Coupe that produces 338 hp and 269 lb-ft. The United States and Canada models deliver 330 hp and 262 lb-ft.
In 2004, BMW launched the lightweight version of S54, officially designated as S54B32HP, HP stands for “High Performance,” is the upgraded version of the S54 engine and was used exclusively for the limited, special edition M3 CSL E46 which has 355 hp and 273 lb-ft torque that weighs 243 lbs. lighter than regular M3s. It has various structural changes to its design to reduce weight; the lightened exhaust system, which is made from thin steel and exhaust manifold with a smoother air path, DME control system and better intake system which is made from carbon fiber, modified camshafts, and MAP sensor in lieu of the MAF sensor which would be the standard in later S54 models. CSL editions are explicitly made for tracks.
Engine Modifications, Upgrades, and Tuning
S54 engines are the last naturally aspirated inline-six M3 engine, and newer M3 models use twin-turbo inline-six. It has the highest horsepower ratio per liter amongst other naturally aspirated six cylinders and can give you increased power gains, but you need to spend extra with that. Some of the upgrades you can do are buying a CSL style intake system headers, evolving software, and performance exhaust, which can give you 370 hp without breaking a sweat. You can also do some bolt-on modifications, and it can increase the horsepower from 275 to 320. But if you plan to go beyond that, you can buy a supercharger and can, depending on the kit, achieve 600 hp at best.
Buying a Supercharger kit, like ESS Supercharger or VF, can give you a lot of power. With the help of this kit, your S54 engine can achieve 400whp – 600whp, and they reliable. This can be installed on your S54 stock internals. You can also add a turbo, though it is not a popular option for S54 engines due to its pricey nature and its small production. And last but not least, do not buy the S54 stroker kit. You can get quality power even without those.
Problems Surrounding BMW S54s
Regardless of its build and maintenance, every engine will eventually surface some problems down the road of its valuable service. And like the S54s, they are not exempted from that. Let us start by comparing BMW S54 with M54, its origin – the former has no significant issues at all. It is more of an age and mileage deterioration, ordinary wear and tear rather than the flaw of its design.
First is the VANOS System. This issue does affect not only S54 engines but also other BMW engines. Vanos solenoids are used in modern, recent turbo BMW engines. So, if you are experiencing any rough idling, power loss, cold starts, and poor fuel efficiency, it might be a VANOS failure. You can solve this by replacing the entire S54 VANOS unit.
The second is the Rod Bearing Failures. Rod bearing issues can be traced way back to 2001, though BMW already replaced problematic rod bearings on those affected engines, there are still reports about the occurrence of such issues up until now. Over-revving might be the root cause of this issue and can escalate to engine failure, which makes this a severe S54 problem.
The third is the periodic overheating on S54. Overheating can be caused by water pump failure, dirty radiator, air in the cooling system, and the thermostat and radiator cap. A coolant leak may also lead to overheating due to its improper coolant flow. S54’s salvation to cool off is to go into the limp mode where the cooling fan will run at maximum effort.
Some additional advice to avoid detrimental effects on S54 engines:
Change the connecting rod bearings, timing chain, and timing chain tensioner at 100,000 miles, especially before 2003 M3 releases.
BMW S54 is a powerful engine with little to worry about because it has no design flaw or any weakness that can affect the machine for a long time. So in terms of reliability, S54s might be the most reliable, so far, and least difficult to deal with in M-series engine production. The lifespan of S54s is also impressively long, as it can serve up to 150,00 miles with the proper maintenance and care, such as scheduled oil change and component replacements.
Definitely, it is one of the best inline-six engines, and as its age, it will continue to inspire future engine ventures that will rise.
I hope that we helped you to clear some things that you do not understand about S54 engines. Whether you are buying or already owned one, I hope that the moment you experience this engine can help you gain more love for these machines.