Reinforced exhaust valves Audi S4 RS4 A6 allroad 2.7T 30V

Audi engines covered

The 2.7T is Audi's turbocharged V6 with five valves per cylinder. It is found in the S4 B5 (AGB, AZB) from 1997, in the RS4 B5 (ASJ, AZR) from 2000 to 2001, and in the A6 C5 2.7T (AJK, APB) and the allroad quattro C5 2.7T (APB) until 2005.

Each cylinder has three inlet and two exhaust valves: 12 exhaust valves are therefore to be replaced, operated by hydraulic tappets. On the APB and AJK, the original part 058 109 611 E measures 29.9 mm at the head, 6 mm at the stem and 103.9 mm in length. A remap or larger turbos increase the heat they have to withstand.

SUPERTECH and FERREA reinforced exhaust valves

On the 2.7T, every exhaust valve opens onto a flow of burnt gases that the turbos make especially hot. The metal of its head sits between 760 and 870 °C on an engine without forced induction, and goes past 1,000 °C as soon as boost rises. To shed that heat, the valve relies on its contacts: about 75 % goes into the seat, some 20 % into its guide bore. As a benchmark, the EV8 family of steels keeps 550 MPa at 600 °C but offers no more than 300 at 800 °C. With a remap or larger turbos, the head runs hotter, tires, warps and the seal is lost.

The reinforced versions change metal to take this heat. At SUPERTECH, all of them are nickel alloys: Inconel, a superalloy that keeps 860 MPa at 732 °C and still 554 MPa at 816 °C, about 85 % more than EV8 steel around 800 °C, comes with one or three grooves; the Nimonic reference has a hollow stem holding sodium, liquid when running, which moves the heat away from the head down to the guide area. FERREA supplies a Competition Plus valve in stainless steel with a chrome stem and three grooves: the brand credits it with 20 % higher hot strength and slower seat wear, giving 25 % more life.

Two SUPERTECH valves come in +1 mm oversize: their head grows from 29.9 to 30.9 mm, while the 6 mm stem and 103.9 mm length stay as original. The gas passage increases, the cylinder clears sooner and its filling improves, to the benefit of power; each of the 12 exhaust seats then has to be recut to the new diameter.

Exhaust valve technical specifications

Valve fitting

The 3 groove AEVI-1103 and FERREA F1554P are fitted with 3 groove collets; the other three SUPERTECH valves, with a single groove, with the KPR-6S/7.

At the standard 29.9 mm size, the exhaust seats keep their diameter; at 30.9 mm, they are recut to the new size during the rebuild.

For the valve stem seals, the original part number on the APB and AJK is 036 109 675 A.

Technical guide

Our brands

	Founded in California, in Silicon Valley, SUPERTECH specialised more than thirty years ago in racing valvetrain parts, titanium retainers included. Its Inconel, titanium or stainless steel valves are studied engine by engine, with help from tuners competing on drag strips, rally stages and race circuits.
	Set up in 1978 by Horacio Ferrea together with Daniel Urrutia, FERREA Racing Components makes its valves between Florida and Argentina, from stainless steel through nickel superalloys to titanium. Engine shops on every continent use them, in NASCAR as in drag racing.

How to choose

Under the retainer, the collets drop into one or three grooves cut in the stem. That number governs how the valve is retained and which collets go with it; the head size then tells you whether the seats need recutting.

When reinforced valves become necessary

• Raised boost or an ECU remap (Inconel or Nimonic recommended)
• Bigger turbos or hybrid turbochargers
• Stiffer springs or more aggressive cam profiles
• Rebuild of a cylinder head meant for track use
• Burnt or marked original exhaust valves

Vehicle compatibility

OEM part number (exhaust valve): 058 109 611 E (APB, AJK)

Don't forget the inlet valves

With the 2.7T head on the bench, it makes sense to replace the inlet valves too, three per cylinder, plus every single valve stem seal. Here they are: