Reinforced exhaust valves BMW M5 E60 M6 E63 S85B50

BMW engines covered

BMW's only production V10, the S85B50 displaces 4,999 cc with the same cylinder dimensions as the S65 V8 (92 x 75.2 mm). Built from 2004 to 2010, it powers the E60 M5 saloon, the E61 M5 Touring and the E63 coupe and E64 convertible M6.

With four valves per cylinder, it has 20 exhaust valves with a 5 mm stem and a single groove, fitted with BMW collets and valve stem seals that are kept with these valves. Long periods at high rpm, on track or on the German autobahn, keep the exhaust ports very hot.

SUPERTECH reinforced exhaust valves

In the S85B50 V10, the 20 exhaust valves open to drive the combustion gases out towards the manifolds. Their head metal runs at 760 to 870 °C as long as the engine stays naturally aspirated, and exceeds 1,000 °C once a supercharger is added. The seat soaks up around 75 % of this heat, while the guide takes 20 %. An EV8 type steel, used here as a point of comparison, copes with 550 MPa at 600 °C and only 300 MPa at 800 °C: at sustained high revs the head builds up heat, works in fatigue, distorts and no longer closes its seat properly.

The SUPERTECH BMEVI-1065 is made from a nobler material, Inconel: this nickel superalloy shows 860 MPa near 730 °C, then 554 MPa near 815 °C, which gives it around 85 % reserve over EV8 in the 800 °C range. It is intended above all for M5 and M6 cars that often see track use or carry a supercharger. Its 5 mm stem has only one groove, just like the BMW valve.

Its sizes are those of the original part: 30.5 mm head and 110.2 mm overall length. On both cylinder heads of the V10, the 20 exhaust valve seats keep their dimension: they only need checking during the rebuild.

Exhaust valve technical specifications

Valve fitting

With its single groove, identical to the BMW part, the BMEVI-1065 is fitted with the original collets, ideally new.

The head diameter stays at 30.5 mm; the exhaust seats only need checking during the rebuild, with no cutting to another size.

On the S85, the BMW valve stem seals are kept.

Technical guide

Our brand

SUPERTECH Performance has designed competition valvetrain parts in California's Silicon Valley for over 30 years: valves, springs, guides, titanium retainers. Made of Inconel, titanium or stainless steel, each model starts from one engine and is developed with renowned rally, circuit and drag racing tuners.

How to choose

The S85B50 has a single reinforced exhaust valve: the BMEVI-1065, in Inconel, which keeps the 30.5 mm BMW head and its single groove. The decision thus boils down to how the car is used and which collets to plan for:

When reinforced valves become necessary

• Supercharger added to the V10 (Inconel version, only reference offered)
• New camshafts or uprated valve springs
• Regular track days in an M5 or M6
• Rev cut pushed back by an ECU modification
• Heads rebuilt after burnt or pitted exhaust valves

Vehicle compatibility

OEM part number (exhaust valve): 11 34 7 833 774 / 11 34 7 838 294

Don't forget the inlet valves

When the S85B50 cylinder heads are off, renew the inlet valves of this V10 at the same time. The reference suited to this particular engine is just below: