The high-rpm Concept

High engine speeds are essential to achieving high power from moderate displacement, but they pose challenges; engineers must ensure that durability standards are met at these levels. The M3 engine's maximum power occurs just below its 8000-rpm limit at 7900 rpm.

To achieve the revving capability, the engineers applied a number of detail measures. A forged, nitro-carbonized steel crankshaft provides great strength in this critical component. Forged-steel "crack" connecting rods eliminate the need for bolt sleeves and thus reduce reciprocating weight.

A unique water pump plays a role too. The crossflow cooling requires high coolant flow. To achieve this, the engineers developed a pump with 3-dimensionally contoured vanes. Such contours would have been inordinately costly to produce in metal, so BMW M developed a novel pump design. Each vane is a small plastic casting, pressed into an also-plastic rotor and then welded into place. Also adding cooling efficiency is a ring thermostat, which imposes less resistance to coolant flow than a conventional plate thermostat.

Electronics play their role too. The engine's control module calculates and adjusts the ignition and fuel injection at each cylinder individually every 6 degrees of crankshaft rotation, it. Ignition occurs through a very small-diameter "pencil" coil at each cylinder.


Spectacular Results: power, torque, revs, performance, sound

All this major and detail engineering work results in a high-performing, great-sounding sports engine. Powered by its 333 hp through the standard 6-speed manual transmission, the M3 Coupe sprints from rest to 60 mph in a thrilling 4.8 seconds, and continues on to an electronically limited maximum of 155 mph. In a March '03 comparison test, Road & Track that "BMW M3's engine possesses an uncannily smooth power delivery. Not only smooth, but also flexible, the M3's six has a wide, usable powerband. Midrange punch is already good, but once above 4000 rpm, the engine adopts an even more menacing snarl as it pulls strongly right up to the redline."


Great looks too: the view under the hood

Following a long BMW M tradition of visually attractive machinery, the S54 engine's appearance is as beautiful as its engineering. Tubing - for the idle air supply, fuel to the injectors, fuel from the fuel pump - is stainless steel. Housed in cast aluminum, the VANOS mechanism projects prominently forward of the cylinder head. Stainless-steel screws secure the camshaft cover. Chrome rings hold the induction trumpets to the ports. The "M" logo and a special M oil filler cap adorn the front of the camshaft cover.

M3 drivetrain: getting S54 power to the road

Like every M Car to date, the M3 transmits its power to the road via classic rear-wheel drive ; the M3 packs some premium and fascinating engineering into its drivetrain.

6-speed manual transmission. Both M3s come standard with the robust and precise Getrag Type D 6-speed manual transmission, crisply controlled by a shift knob with illuminated shift pattern and M logo. The transmission housing incorporates NACA air intakes which, together with careful aerodynamic design of the underbody, help keep internal transmission temperatures under control. The optional Sequential Manual Gearbox is described later in this text.

Super-sized differential unit. A specific subframe allows equipping the M3 with the same heavy-duty differential dimensions as in the previous 394-hp M5. A special high-strength steel alloy is used for the differential gears to achieve quietness and durability, and a relatively "short" 3.64:1 final drive ratio exploits the engine's generous torque and rpm range while 6th gear keeps it humming moderately at cruising speeds. Here too, targeted airflow under the vehicle, along with a ribbed differential case, helps keep the oil cool.

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