Dec 31, 2008

BMW’s screaming S54B32 inline-6 laid to rest

The last application of the venerable S54B22 in a BMW car was the BMW Z4 M, which featured the motor in a slightly detuned form as compared to the one that made its debut in the E46 BMW M3. The M3’s S54B32 made 343hp at a screeching 7,900rpm and 365Nm of torque at 4,900rpm while in the Z4 M, this was reduced to 315hp at 7,900rpm and 340Nm at 4,900rpm.

When you look at the S54B32 engine code, it tells you that the engine is a Sport engine from the 54 engine family (S54), is fuelled by Benzine (B), and is 3.2 liters in displacement (32). It uses a cast iron block (to withstand the high pressures), graphite-coated cast aluminium pistons, high 11.5:1 compression, double VANOS, electric throttle operation and one throttle per cylinder.

It won the International Engine of the Year award for the year 2001, together with the Best New Engine award. The engine also took the 3.0 liter to 4.0 liter engine honour from 2001 to 2006.

The S54 will not be used in any BMW application anymore, and in its place is the new N54 twin-turbocharged engine, which makes 326hp in its latest application, the F01 BMW 740i. The two turbochargers are run in parallel, unlike BMW’s twin-turbodiesel which has a sequential arrangement with two turbochargers of different size.

The N54’s peak horsepower output is lower than the S54’s highest rated horsepower but the N54 offers so much more torque - between 400Nm to 450Nm depending on whether it’s in a 1/3-Series or the new F01 7-Series. The torque is also accessible across a much wider range, making it a much more practical engine for daily driving. Thus the “successor” in terms of engine at least to the Z4 M is the new Z4 sDrive35i, but we all know there’s going to be something more exciting when the new Z4 M comes out.