The S54 and N54 are high-performing inline-6 engines from BMW. Although very different in terms of design and power delivery, these are both legendary engines that will go down in history as some of the best inline-6 motors.
Let’s take a detailed look and comparison between the S54 and N54:
|Configuration||NA Straight-six||Twin-turbo Straight-six|
|Block Material||Cast iron||Aluminum|
|Valvetrain||DOHC with Variable Valve Timing (VANOS)||DOHC w/ Variable Valve Timing (double VANOS)|
|Redline||8,000 rpm||7,000 rpm|
|Max. Power and Torque||338 bhp at 7,900 rpm; 269 lb⋅ft at 4,900 rpm||302 bhp at 5,800 rpm; 295 lb⋅ft at 1,400-5,000 rpm|
S54 vs. N54 Performance & Horsepower
Both of these engines make a lot of power from the factory, with very respectable horsepower and torque figures even in stock form.
Power delivery is very different on both engines, the S54 being a high-revving naturally aspirated engine with most power high in the rev range and the N54 having twin-turbos, giving it plenty of torque down low that dies out in the high rpms.
When looking at the dyno chart of both engines, we can see how the N54 produces a high and consistent amount of torque from as low as 3,000 rpm all the way up to 5,500-6000 rpm, making it an awesome daily driver. The S54 on the other hand needs be revved up high to unleash its true performance figures, and revving it up all the way to redline on public roads could get you into serious trouble.
S54 vs. N54 Tuning
The N54 has a well-deserved reputation among the car tuning community. The N54 engine is stout, well receptive to modifications and a stock engine block can handle up to 750 wheel horsepower. A single turbo N54 with the respective accompanying bolt-ons can make 900 wheel horsepower reliably, a feat that makes the N54 comparable to the venerable 2JZ engine in the MK4 Toyota Supra.
The N54 is more tunable than the S54, with the potential to make tons of power with just a few mods and a tune
On the other hand, the naturally aspirated S54 engine is not as receptive to modifications. Full bolt-ons can bump power output moderately and there are available supercharger & turbocharger kits for a forced induction setup.
S54 vs. N54 Reliability & Maintenance Costs
The S54 was the last naturally-aspirated inline-6 used on a BMW M3 while the N54 was the first twin-turbo direct-injection inline-6 engine made by BMW. This alone should tell you a lot about the reliability of both powertrains.
The N54 is known for injector failure, water pump failure, turbo wastegate rattle, vacuum leaks, among other issues. Of course, it also suffers the usual gasket leaks of any BMW engine. The engine block is solid and can handle tons of abuse and additional power without skipping a beat, but a lot of components around it tend to fail. Later iterations of the injectors and other ancillary components improved reliability but this is an engine that requires constant maintenance and can cost a fortune to maintain if you’re not DIY-inclined.
On the other hand, the S54 features a more simple design without turbochargers and without cutting-edge direct injection system. The S54 could be considered the pinnacle of high-revving high-performance naturally aspirated inline-6 engines, and this helps greatly in terms of reliability. That is not to say the S54 is bulletproof; it’s common problems include road bearings, VANOS issues, and water pump failure.
The S54 is more reliable than the N54, although both engines are high-maintenance
Even with its rod bearing issues, the S54 is a more reliable engine than the N54. Both engines can easily make it to 250K+ miles, both the N54 will likely cost you more in the process.
S54 vs. N54 Sound & Exhaust Note
These two engines have completely different exhaust notes. The difference lies mostly in one being a turbocharged engine that makes most of its power down low in the RPM range and the other one being a naturally aspirated one that likes to be revved up high.
Although ranking exhaust sounds from best to worst is a very subjective matter, the vast majority of people would agree that the S54 sounds vastly better than the N54. The twin-turbo setup of the N54 with a stock exhaust muffles a lot of the sound without extensive exhaust work or upgraded turbos.
There’s no doubt that there are incredible sounding N54’s out there with aftermarket exhaust systems, and turbo sounds are awesome but no straight-six engine can beat the note of the high-revving S54. Even in stock form with a stock exhaust the N.A. S54 has a superior sound compared to the N54.
The S54 sounds much better than the N54
S54 Engine Sound:
N54 Engine Sound
N54-powered E90 335i vs S54-powered E46 M3
We’ve been comparing just the engines so far, but what about the most symbolic cars that are powered by the N54 and the S54?. We’re talking about the early E90 335i with year models from 2007 to 2010 compare to the mythical E46 M3.
The S54-powered E46 M3 is without a doubt the car with the superior handling, balance, raw feel and nimbleness, while the N54 335i can be faster in a straight line, while also being more comfortable and refined for daily cruising.
Related article: M54 vs N52 engine comparison