Reinforced inlet valves AUDI S2 RS2 S4 S6 3B 7A AAN ADU

AUDI engines covered

The Audi 2.2 litre 20-valve turbo five-cylinder powers the 200 20V Turbo and the S2 (engine code 3B, 220 hp), the C4 generation S4 and S6 (AAN, 230 hp) and the RS2 Avant (ADU, 315 hp), from 1989 to 1997. Its naturally aspirated 2.3 litre version, the 7A with 167 to 170 hp, is fitted to the 90 and Coupe 2.3 20V from 1988 to 1996.

Each engine has 10 inlet valves, two per cylinder, operated by hydraulic tappets. The Audi part 027 109 601 C has a 32.0 mm head, a 7.0 mm stem and a 95.5 mm length. Raised boost, sharper camshafts or higher revs: every modification adds heat and impact on their seats.

SUPERTECH and FERREA reinforced inlet valves

On the Audi 20V five-cylinders, ten inlet valves, two per cylinder, open and close the air path, pressurised by the turbo on the 3B, AAN and ADU. With the engine running hard, each one lifts off its seat and hammers back down, dozens of cycles in every second, while its stem travels up and down the guide. It operates between 400 and 550 °C; there the stock chromium-silicon steel already drops: 500 MPa at 500 °C, 250 MPa at 600 °C, only slightly higher, so 50 % lost. Every increase in boost, lift, spring rate or revs multiplies impacts, friction and heating.

The FERREA 6000 Series valves use EV8 (21-4N) stainless and a hard chrome stem. This chromium-nickel grade keeps 650 MPa at 500 °C, 30 % more than the original steel, and 550 MPa at 600 °C, 120 % more; the hard chrome shields the stem in its guide. The SUPERTECH valves combine stainless steel treated with black nitride, whose hardened, smoothed outer layer cuts stem friction and wear, with a slightly dished head face. Both brands supply sets of 10 to equip the whole engine.

Two oversizes are available: 32.5 mm (+0.5 mm) from SUPERTECH and FERREA, 34.0 mm (+2 mm) from SUPERTECH, versus 32.0 mm as standard, with the 7 mm stem and 95.5 mm length unchanged. The larger diameter opens up the passage at the seat; filling gets better and the five-cylinder gains power, once all 10 inlet seats have been recut to the new diameter.

Inlet valve technical specification

The VWIVN-1034-10, VWIVN-1035-10 and VWIVN-1038-10 have a slightly dished head.

Fitting details

The single groove SUPERTECH valves are fitted with the KPR-VW7-S single groove collets the manufacturer specifies for this engine.

At 32.0 mm, the valves sit on seats reconditioned to the factory size; at 32.5 and 34.0 mm, the inlet seats are cut to the head diameter.

The hydraulic tappets take up the clearance by themselves: no adjustment is needed after reassembly.

Technical guide

The brands offered

	Founded in 1978 at Fort Lauderdale by two Argentinian tuners, FERREA Racing Components builds everything in Florida. Each valve is forged in one block from bar, then fully finished under CNC; the brand is found in NASCAR as much as in drag racing or on circuits.
	Headquartered in San Jose, California, SUPERTECH has been creating racing engine valvetrain parts for more than 30 years. Its valves are designed for one precise engine, inspected part by part by ultrasound, radiography and laser, and validated with tuners, from drag racing to the circuit.

How to choose

Sitting in the stem groove below the retainer, collets lock the valve. Choose size from seat condition first, then material from planned use.

When reinforced valves become necessary

• Bigger turbo or more boost
• Raised rev ceiling
• More aggressive camshafts or stiffer valve springs
• Head reconditioned for rally, hillclimb or circuit
• Worn or pitted factory Audi valves, or seats reground before

Compatible vehicles

OEM part number (inlet valve): 027 109 601 C

Related products

Before refitting the 20V five-cylinder head, plan reinforced exhaust valves as well as fresh stem seals. The parts for these engines are here: