BMW S85B50 Engine

Appearing in 2005, the BMW S85B50 5-liter ten-cylinder V-twin engine was immediately recognized as the winner in the category “Best Engine over 4.0L” at the annual competition of the automotive industry of internal combustion engines “International Engine of the Year”. This power unit held the first position for 4 years in a row and belongs to the 5th generation BMW E60/E61 engines produced from 2005 to 2010.

Motor characteristics S85B50

Advantages

This high-revving automotive unit, whose technology is based on the engine of the BMW Williams Formula 1 sports car, has no prototypes, has been developed by engineering specialists specifically for the BMW E60 M5 model.

With an engine displacement of 4999cm³ and 507hp at 7750rpm, which can accelerate the car to a speed of 100km/h in just 4.7s, makes the car competitive with no less famous brands of similar class. The 10-cylinder block of the S85B50 engine is cast from a special aluminum alloy, without liners. The cylinders are positioned at an angle of 90°, which reduces vibration transmitted to the crankshaft and balances the weight of the engine.
The crankshaft, offset by 17mm, made of high-strength forged steel, is supported by 6 bearings. The 5 journals each carry 2 connecting rods at an angle of 72°. The pistons are made of a heat resistant aluminum based alloy. 2 timing shafts mounted in the block heads control 4 valves in each cylinder, cast from a special alloy, as do the hydraulic tappets.

Each cylinder is provided with its own throttle valve, facilitating optimal fuel response of the S85B50 V10 engine at low crankshaft speeds (typical of race cars) and is electronically regulated. Three processors, each with 32 digits, of the MSS 65 electronic unit control the engine, adjust the required gasoline dosing parameters for each operating mode, and implement and coordinate the gas distribution phases. Double-VANOS gas distribution technology in combination with VALVETRONIC valve lift control device provide rational fuel consumption, maximum performance to improve torque. Ignition – mounted in the ECU, which is critical to engine performance.

BMW S85B50 lubrication system – complex, consisting of 4 pumps. In addition to the main function, supplying oil to the rubbing parts, they perform an additional function – reverse supply of lubricant at increased lateral acceleration, disrupting normal circulation.

Disadvantages

Taking into account that the engine under consideration has taken the first place in the nomination “Best Engine over 4.0L” for 4 years, the reliability of its operation has been confirmed by time. At the same time, the S85B50 engine has its own problems, which have been revealed during a long period of operation.

The most “weak” link in the internal combustion engine is the connecting rod liners. Auto mechanics experts recommend their replacement after 80 000 km of mileage. And in the inter-repair period it is necessary to perform regular maintenance. When changing the oil, pay attention to the condition of the filter element and spent lubricant.

The appearance of small chips is the first sign of the need for repair work. It is not uncommon for VANOS to cause headaches for motorists. The main reason is the raw material for the manufacture of the sealing ring of the equipment piston, which has limited resistance to elevated temperatures and environments that cause a deleterious effect on the material. After some time, the elasticity is lost, the product hardens. This leads to the formation of internal leakage, increase in permissible clearances and as a consequence – failure in the operation of the timing mechanism.

Wear of the needle-shaped bearing, metal washer in the piston causes increased clearance and noise when the engine is running.
Foreign bodies (chips, debris, burrs on the piston rim of the product), breakage of the supply wire to the solenoid valve are possible causes of VANOS valve malfunction.

Modifications

The technical characteristics of the S85B50 engine do not quite meet the modified requirements of the American LEV II and European Euro-4 regulations, which have strict toxicity standards. To bring the engine up to these requirements, the neutralizers are mounted closer to the engine, providing quick heating, reducing emissions.

The S85B50 served as the basis for the production of the S65B40 engine, by converting it to a V-8. The cylinder block, cylinder spacing, piston and connecting rod design, valves and springs remained the same as on the base model. At the same time, the displacement was reduced to 4 liters.
If the structural scheme of the cylinder head has not changed, the Double-VANOS timing control system has undergone a significant change. The power of the “clone” has been significantly reduced and leaves 420 hp at 8300 rpm.

Chip Tuning

Compressor S85

A reasonably proven way to increase engine power is to install the time-tested ESS S85 VT2 kit on a Vortech V3Si base, which can add up to 650hp. In addition to the resulting turbo, the ESS crank liners must be replaced.  Installation of a more powerful compressor requires additional investment of funds, which is not always rational in the mode of observing the reliability of the engine.

Atmo S85. Stroker

The S85 powertrain has good factory power specifications (101hp per 1 liter of displacement). If you want to increase power, you need to perform some additional conversions. The most common method is to replace the exhaust system with a sports exhaust, without a catalytic converter, with the appropriate adjustment of the control unit. The use of Gruppe M intake and pulley replacement, together with the replacement of the exhaust, give an increase of up to 50 hp.  There are stroker kits that allow you to increase the literage to 5.8 liters, which significantly increases the power of the engine up to 630 hp.

This engine is installed on the following models:

BMW M5 (E61)

BMW M5 (E60)

BMW M6 (E64)