BMW S38
BMW S38 Engine
BMW S38 engine specs
| Manufacturer | Munich Plant |
| Also called | BMW S38 |
| Production | 1988-1996 |
| Cylinder block alloy | Cast-iron |
| Configuration | Straight-6 |
| Valvetrain | DOHC 4 valves per cylinder |
| Piston stroke, mm (inch) | 86 (3.39) – S38B36 90 (3.54) – S38B38 |
| Cylinder bore, mm (inch) | 93.4 (3.68) – S38B36 94.6 (3.72) – S38B38 |
| Compression ratio | 10.0 10.5 |
| Displacement | 3535 cc (215.7 cu in) – S38B36 3795 cc (231.6 cu in) – S38B38 |
| Power output | 235 kW (316 HP) at 6,900 rpm 250 kW (340 HP) at 6,900 rpm |
| Torque output | 360 Nm (266 lb·ft) at 4,750 rpm 400 Nm (295 lb·ft) at 4,750 rpm |
| Redline | 6,200 |
| HP per liter | 89.4 89.6 |
| Fuel type | Gasoline |
| Weight, kg (lbs) | 151 (333) |
| Fuel consumption, L/100 km (mpg) -City -Highway -Combined |
for E34 M5 18.0 (13.1) 8.3 (28.3) 9.6 (24.5) |
| Turbocharger | Naturally aspirated |
| Oil consumption , L/1000 km (qt. per miles) |
up to 1.0 (1 qt. per 750 miles) |
| Recommended engine oil | 5W-30 5W-40 10W-40 15W-40 |
| Engine oil capacity, L (qt.) | 8.0 (8.45) – S38B36 5.75 (6.05) – S38B38 |
| Oil change interval, km (miles) | 5,000-10,000 (3,000-6,000) |
| Normal engine operating temperature, °C (F) | ~90 (195) |
| Engine lifespan, km (miles) -Official information -Real |
– 400,000+ (250,000) |
| Tuning, HP -Max HP -No life span loss |
500+ – |
| The engine is installed in | BMW M5 E34 |
BMW S38 engine reliability, problems and repair
The S38B36 engine designed especially for BMW E34 M5 which released in 1988. This engine based on naturally aspirated M88/3 (S38B35). S38 has less common with M30B35. In the M88/3 cylinder block used lightweight forged crankshaft with a stroke of 86 mm and 12 counterweights. The diameter of the cylinders left unchanged (93.4 mm). The pistons have been modified: compression height 31.5 mm, compression ratio – 10:1, S38B36 rod length – 144 mm.
Cylinder head of BMW S38 is the 24-valve with two camshafts and with solid lifters. Adjustment the valves is carried out as required. The clearances of the valves (cold engine): 0.28/0.33 mm. Stock S38B36 camshafts specs are: duration 264/110 deg, lift 10.7 mm. The size of inlet valves is 37 mm outlet 32 mm. Camshafts are set in motion by double row timing chain.
On intake installed variable-length intake manifold and individual throttle bodies (ITB). The diameter of each throttle body – 46 mm. Fuel injectors have a capacity – 270 cc/min. The engine control unit – Bosch Motronic M1.2. On exhaust applied equal length exhaust header. These upgrades allowed to get power in 316 horsepower at 6,900 rpm.
S38B36 motor upgraded since 1992. Main difference between S38B36 and S38B38 following: the new crankshaft with a piston stroke of 90 mm and with 12 counterweights, new connecting rods (lenght 142.5 mm), the diameter of the cylinders increased to 94.6 mm, lightweight pistons with a compression height of 30.7 mm and a compression ratio 10.5:1. As a result displacement increased to 3.8 liter.
Modifications were made in the cylinder head of S38B38: diameter of inlet valves increased to 38.5 mm, exhaust to 32.5 mm. Also intake and exhaust ports were upgraded. Specs of S38B38 camshafts following: duration 264/108 deg, lift 10.7 mm. The intake manifold was modified, the diameter of each throttle body is increased up to 50 mm. Exhaust system is also new.
The engine control unit – Bosch Motronic 3.3 DME.
All this improved behavior of the car on low and mid revs and increased power to 340 horsepower at 6,900 rpm.
Production of sports S38 stopped in 1996, together with E34 M5. There was new BMW E39 M5 with absolutely other S62B50 engine in 1998.
BMW S38 engine problems and malfunctions
The main sickness are the same as at M30 (an overheat and cracks in the block). Learn more about them HERE. In addition are possible leaks of rear crankshaft oil seal. Also sometimes there is loud whistling sound at idle (during initial running).The reason is a failed catalytic converter.
Anyway, the S38 engine is good, but is very old and worn-out. To buy BMW M5 E34 today is not the best idea. If you manage to find the car from the true fan, then buy without hesitation.
BMW S38 engine tuning
S38 Stroker. N/A Build
The easiest way to increase the power of BMW M5 E34 is buy Schrick camshafts 280/280 with springs, fuel injectors 440 cc/min, carbon airbox, 6-2-1 header, performance exhaust system.
After that you need to adjust ECU under new aftermarket performance parts. It is good kit for the daily car. On S38B38 it will give about 380 horsepower, and on S38B36 about 350 horsepower.
It is possible to increase S38B36 power by installing S38B38 intake system, camshafts 296/280, to do head porting, to buy the increased inlet valves (39 mm). As a result you get about 390 horsepower.
The same kit on S38B38 will give about 420 horsepower.
If you need more, then buy lightweight high compression pistons (95 mm), lightweight Carrillo rods, install camshafts 304/296 and Haltech E11 ECU (or another). As a result on S38B38 you get about 450 horsepower. The same kit on S38B36 will give about 420 horsepower.
In addition to all this, you can buy the S38 stroker kit. By installing a crankshaft with a stroke of 98 mm, H-beam rods, forged pistons 95 mm (CR=12), you will get a 4.2 liter capacity.
S38 Turbo. Supercharger
Furthermore, on stock BMW E34 M5 engine you can install a turbocharger or the supercharger and get about 450 horsepower. For this you need a classical kit: ARP studs, MLS head gasket, plenum, Garrett GT42 turbocharger, turbo manifold, pipes, intercooler, wastegate, blow-off, fuel injectors 630 cc/min, Bosch 044 fuel pump, performance exhaust system 3”, Megasquirt ECU. On max boost 7 psi (0.5 bar) you get about 500 horsepower on S38B38. If to install such turbo kit on S38B36, you get 450-470 horsepower.
In addition buying forged pistons (CR=8.5), H-beam rods, you can increase boost and get 600 horsepower and more. Such a project can be made using a supercharger. Such supercharger kits on stock internals may increase power to 450 horsepower.
