New Model - General Information
Group 00Maintenance and
General Hints
Bulletin Number
00 01 94 (2140)
Woodcliff Lake, NJ
June 1994
Product Engineering
SUBJECT:
M3 General Information
MODELS:
E36 M3
General Information:
With the introduction of the E36 M3, BMW expands the 3 Series lineup to include a high performance model which is based on the 325i coupe. The Motorsport designed M3 includes the new S50 US B30 six cylinder engine coupled with a manual ZF transmission designated S5D 310Z, a strengthened clutch assembly, and modified suspension and brake systems.
Body features include:
Many interior features have been carried over from the 325is model with the exception of the unique M3 components:
The instrument cluster is identified by the M-style logo (1). The indicator needles (2) are red, and the tachometer (3) has been recalibrated to a maximum reading of 8000 rpm.
The steering wheel rim/grip area is a thicker diameter as compared to the 325is, and includes the Motorsport colored stitching on the inside edge of the wheel.
The shifter knob also displays the Motorsport colors.
The newly designed 12-way adjustable manual sport seats feature a headrest which is attached to the shoulder bolsters of the upper seatback. When the headrest is adjusted (up or down) the shoulder bolsters height is also adjusted, thus providing additional upper body support and conformance to the driver's size.
The new 3.0 liter six cylinder four valve engine designated S50 B30 US incorporated in the M3, is based on the M50TU B25 engine.
The S50 B30 US engine develops 240hp (179 kw) at 6000 rpm with a maximum torque output of 225 ft.lbs. (305 N-m) at 4250 rpm. This is a 21.25% horsepower increase and a 19.5% torque increase in comparison to the M50TU engine found in the 325is model.
The grey cast iron crankcase is the same as the M50TU engine except for the increased bore size of 86 mm.
As in the M50TU engine, the S50 US crankshaft is made of spheroidalgraphite cast iron. The stroke of the crankshaft has been increased to 85.8 mm.
The pistons are a box pattern design (the same design used on the M50TU engine) and incorporate symmetrical combustion bowl crowns which are notched for valve head clearance.
Forged connecting rods are used which measure 135 mm in length.
The flow characteristics of the crossflow, four-valve cylinder head have been improved compared to the M50TU engine by precision flow bench testing and port polishing thus optimizing intake and exhaust gas transfer.
The valve train has been modified to include the following changes when compared to the M50TU engine:
The camshafts are specially designed for the S50 US and allow for increased valve lift; intake = 10.3 mm (1.3 mm increase) and exhaust = 9.7 mm (0.7 mm increase) and increased valve open duration; intake = 2520 (24~ increase) and exhaust = 240~ (12~ increase).
Valve spring tension along with the outside diameters of the valve spring, spring plates and hydraulic valve lifters (HVA) have all been increased.
The variable intake valve timing system (VANOS) is used on the S50 US engine, which improves the mid-range torque output, reduces exhaust emissions, increases throttle response, and improves idle quality by varying the intake valve timing (camshaft position) during operation. The function. description of the VANOS system is outlined in TRI 11 03 92 (2125).
The Bosch Motronic System DME 3.3.1 is used on the S50 US engine which features the following functions:
^ Ignition timing management
^ Fully sequential fuel injection
^ Cranking & cold starting enrichment
^ Adaptive - oxygen sensor control
- idle speed control
- purge valve control
^ Mixture enrichment during warm-up
^ Mixture enrichment when accelerating
^ Deceleration fuel cutoff
^ Catalytic converter protection via fault monitoring of the primary and secondary ignition circuits
^ Self-diagnosis and fault memory
^ Emergency operation program i.e., in the event of a missing input to the control module, substitute values assure reliable engine operation
^ VANOS control
^ Cylinder selective knock control with 2 knock sensors capable of monitoring all 6 cylinders individually
Technical Data
The ZF 5-speed manual transmission designated S5D 310Z is used on the M3 due to its increased torque rating of 310 N-m.
The dual mass flywheel used in the M3 has recalibrated torsion dampers as compared to the standard flywheel and is matched to a large 240 mm diameter clutch disc. A diaphragm type pressure plate with an increased spring rate is used to handle the performance requirements.
The design and function of the M3 steering and suspension systems are adapted from the 325is model with specific Motorsport modifications due to the increased power output and road handling demands.
The front steering geometry is modified for improved steering characteristics by slightly changing the caster/camber angles, which is accomplished by the repositioning of the mounting holes for the upper strut assembly in the strut towers.
Other changes on the front suspension include:
The rear suspension incorporates reinforced trailing arms (1), recalibrated shock absorbers (2) and firmer/larger diameter springs (3).
The rear differential on the M3 features a 25% limited slip with a 3.15:1 final drive ratio.
The brake system design used on the M5 is incorporated on the new M3 which features:
- ventilated front brake rotors, 315 mm-diameter x 28 mm-thick
- ventilated rear brake rotors, 312 mm-diameter x 20 mm-thick
- larger brake pads and calipers (compared to the 325is)
A modified version of the Teves ABS system found on the 325is is used on the M3, which includes a new hydraulic unit and a reprogrammed electronic control module.
The low profile 235/40 X 17 ZR high-speed tires are mounted on the newly designed ten spoke 7.5J X 17 light alloy Motorsport wheels.