The heart of the E60 M5 is the S85B50, a 5.0-litre V10 that revs to 8,250 rpm. It is one of the most celebrated naturally aspirated engines of its era, and understanding how it works explains much of the car's character.
Basic layout
The S85 is a 90-degree V10 with four valves per cylinder and two overhead camshafts per bank. Its bore is larger than its stroke (an "oversquare" design), which keeps piston speeds manageable at very high rpm. With a displacement of 4,999 cc it produces 507 hp at 7,750 rpm and 520 Nm of torque at 6,100 rpm.
Built to rev
High engine speed is the central idea of the S85. To make it reliable at more than 8,000 rpm, the engineers focused on keeping moving parts light and stiff:
- A forged crankshaft and lightweight pistons reduce the inertia of the rotating assembly.
- The block is aluminium with a closed-deck style construction for rigidity.
- A sophisticated oiling system was designed to keep lubrication stable during hard cornering and high rpm.
Ten individual throttle bodies
Instead of a single throttle, every cylinder has its own throttle butterfly. The throttles are operated electronically by actuators, one for each bank. Individual throttle bodies give a very direct response to the accelerator pedal and contribute to the engine's sharp, motorsport-like sound at high rpm.
Double VANOS
The S85 uses BMW's double VANOS variable valve timing on both intake and exhaust camshafts. Unlike many road engines, it operates with high-pressure oil supplied by a dedicated pump, allowing very fast adjustment of the cam timing. This helps the engine deliver usable torque at low speed while still breathing freely near the redline.
Engine management
The engine is controlled by a powerful Siemens engine-management unit. Among its notable functions is ion-current measurement, which uses the spark plugs themselves to detect combustion quality and knocking in each cylinder. This allowed the engine to run close to its limits safely.
Sound
A V10 has an irregular-sounding firing pattern at idle and a smooth, high-pitched scream as the revs climb. The combination of ten cylinders, individual throttle bodies and a freely flowing exhaust is why the E60 M5 is often described as one of the best-sounding saloons ever made. You can hear it on our homepage — press Engine Start and hold Gas.
What owners should know
An engine that is this highly stressed rewards careful ownership. Warming the oil fully before using high rpm, using the correct oil specification and following a sensible maintenance schedule are all important. Our maintenance checklist covers the main points.
This article is an educational overview written by enthusiasts. Always rely on a qualified technician and official documentation for repair work.