The BMW S38B38 engine, which debuted in 1992, was based on the S38B36. It featured a crankshaft with a 90 mm piston stroke and 12 counterweights, connecting rods that were 142.5 mm long, an increased cylinder diameter of 94.6 mm, new lightweight pistons with a compression height of 30.7 mm, an increased compression ratio of 10.5, and a working volume of 3.8 liters.
Additionally, the S38 cylinder head was altered by finalizing the intake and exhaust channels and increasing the diameter of the intake and exhaust valves to 38.5 mm and 32.5 mm, respectively. The S38B38 has 264/108 camshafts with a lift of 10.7 mm. The throttle bodies’ diameter has been increased to 50 mm, and the intake manifold has been redesigned. The control unit, Bosch Motronic DME 3.3, is also new.
All of this allowed for an increase in power to 340 horsepower at 6900 rpm and an improvement in the car’s behavior at low and medium speeds.
Specifications
| Production years | 1992-1996 |
| Displacement, cc | 3795 |
| Fuel system | injector |
| Power output, hp | 340 /6900 rpm |
| Torque output, Nm | 400 /4750 rpm |
| Cylinder block | cast iron R6 |
| Block head | aluminum 24v |
| Cylinder bore, mm | 94.6 |
| Piston stroke, mm | 90 |
| Compression ratio | 10.5 |
| Oil consumption, gr/1000 km | up to 1000 |
| Recommended engine oil | 5W-30, 5W-40, 10W-40, 15W-40 |
| Engine oil capacity, liter | 5.75 |
| Fuel type | petrol |
| Fuel consumption, L/100 km (for E34 M5) — city — highway — combined |
18.0 8.3 9.6 |
| Engine lifespan, km | ~400 000 |
| Weight, kg | ~151 |
Disadvantages of the S38B38 engine
The possibility of the unit’s cylinder block cracking stands out among the impressive list of malfunctions. Cracks start to appear close to the threads where the cylinder block bolts are fastened. Such a breakdown appears when there is oil in the thread and when the unit is disassembled frequently. It is simple to identify this breakdown. An increase in antifreeze consumption and the presence of an emulsion in the oil are immediate indicators of its presence. Installing a new unit is the only way to stop this breakdown.
Only three circumstances cause the S38B38 motor to overheat. blocked thermostat, pump, or radiator. This issue can occasionally arise from a cooling system plug.
failure of the crankshaft to start the engine. This breakdown may appear as a result of the starter failing, the terminal being improperly fastened, or the ground bus on the engine body being disconnected.