This Is The Highest-Revving Inline-6 Engine Of All Time

The inline six-cylinder engine that revs the highest, as indicated by its amazing 7,900 rpm redline, is the BMW S54. This 343-hp naturally aspirated engine, produced from 2000 through 2008, powered a variety of BMW models, including the E46 M3, the Z3 M Coupe and Roadster,  and the Z4 and Z4 M Coupe and Roadster. It was even used by Germany’s Weismann for its MF3 model retro sports car. A later, upgraded version with 360 hp, thanks to an improved intake manifold and camshafts, was called the S54B32HP and appeared in the E46 M3 CSL. And while the BMW S54 engine may not quite rank up there with the highest-revving engines ever released in a production car, it is definitely one of BMW’s iconic inline six engines, ranked by horsepower.

One of BMW’s primary goals with the S54 engine was to create a powerplant that could support an output of 100 hp per liter. They achieved this goal, as its 343 hp generated by a 3.2-liter displacement comes out to 107 hp per liter, which increased to over 112 hp/liter with the higher-output S54B32HP version. Mission accomplished.

The BMW S54 engine featured an iron block combined with an aluminum head and individual throttle bodies. It used dual overhead camshafts to activate its four valves per cylinder. New technology (for the year 2000) added to the S54 included new engine management software making 25 million calculations each second while controlling its cooling system, fuel injection, and timing of the ignition. Forged connecting rods and pistons completed the package. 

While the BMW S54 engine was designed for high performance, it requires a scrupulous approach to maintenance, having some well-known, long-term weaknesses. One is its virtually guaranteed-to-fail cooling system. Its cooling system is virtually guaranteed to fail, due to BMW’s use of plastic end tanks on the radiator. Its water pump is also known to have a short lifespan. A service interval of just 60,000 to 80,000 miles for thermostat, expansion tank, and coolant hose replacement is recommended. The S54 is also prone to excessive wear of the connecting rod bearings, with preventative replacement suggested every 60,000 to 100,000 miles.

Another area of concern with the S54 engine is the VANOS variable valve timing system, which is subject to wear and breakage. It should be serviced every 80,000 miles. Other S54 trouble areas include the throttle actuators, the coil packs, and the spark plugs. 

If you own a BMW with an S54 engine sitting under the hood, it is not an engine you can just forget about. Changing the oil regularly with a good synthetic and checking it frequently is a good start. Maintain its individual systems, particularly those that can fail. Take care of your S54 and it will take care of you, especially if you happen to be a track rat. The S54 engine powers one of the legendary vehicles that were powered by inline-six engines. It will always be remembered as one of the final high-redline BMW engines that was made before BMW made the switch to turbocharged engines for its lineup of M vehicles.