Reinforced inlet valves HONDA K20C1

HONDA engines covered

The K20C1 is Honda's 1,996 cc 16-valve turbocharged four-cylinder of the Civic Type R, from 300 to 330 hp: Civic IX FK2 from 2015, Civic X FK8 from 2017 and Civic XI FL5 from 2022.

It has 8 inlet valves, two per cylinder. Boost pressure, a sharper camshaft, stiffer springs or a higher rev limit ask far more of them than stock use.

SUPERTECH and FERREA reinforced inlet valves

On the inlet side, each valve opens and closes dozens of times a second at high rpm, strikes its seat and slides constantly in its guide, at 400 to 550 °C. At these temperatures the chrome-silicon steel of stock valves drops from 500 MPa at 500 °C to 250 MPa at 600 °C: it loses 50 % of its strength.

SUPERTECH makes these valves from an EV8-type racing stainless steel: 650 MPa at 500 °C and 550 MPa at 600 °C, i.e. 30 % then 120 % more than stock steel. Their black nitride treatment hardens and smooths the surface, which cuts friction and stem wear in the guide. FERREA offers its Competition Plus series, which the maker quotes as 20 % stronger when hot and under fatigue, with a seat lasting 25 % longer, as well as its 6000 Series.

SUPERTECH and FERREA supply it in the engine's standard size, 35.0 mm head and 5.48 mm stem; FERREA adds a +1 mm oversize, 36.0 mm head, which widens the passage at the seat for better cylinder filling, provided the inlet seats are cut to this size.

Inlet valve technical specification

HIVN-1060D-8: dished head.
FERREA: valves intended for the K20C1 Civic Type R.

Fitting details

Technical guide

Our brands

	SUPERTECH, based in San Jose, California, has designed valvetrain parts for racing engines for more than 30 years: valves, springs, retainers, guides. Each valve is drawn for a given cylinder head, checked by ultrasound, X-ray and laser, then proven with engine builders, at the drag strip as on the circuit.
	FERREA Racing Components set up in Fort Lauderdale, Florida, in 1978, at the initiative of two engine builders of Argentine origin. Its valves start as steel bar forged in one piece, then go entirely through CNC machines before running in NASCAR or drag racing.

When reinforced valves become necessary

• Higher-lift camshafts or stiffer springs
• Raised rev limit
• Turbo or supercharger fitted
• Cylinder head rebuilt for circuit, hill climb or rally
• Original valves marked, worn or already reground

Compatible vehicles

Related products

For a rebuilt K20C1 cylinder head, the reinforced exhaust valves are available here: