Reinforced inlet valves HONDA S2000 F20C F22C1

HONDA engines covered

The F20C is Honda's 1,997 cc four-cylinder with twin overhead camshafts, 16 valves and VTEC, fitted to the S2000 AP1 from 1999 to 2009 with 231 to 250 hp depending on version. The 2,156 cc F22C1, with 239 to 243 hp, replaced it in the S2000 AP2 from 2003.

Each engine has 8 inlet valves, two per cylinder; on the F20C the Honda part number is 14711-PCX-000, with a 5.48 mm stem, held by 14781-PR7-A01 collets. Their original head measures 36 mm. Higher revs, sharper camshafts or stiffer springs load them far beyond standard use.

SUPERTECH and FERREA reinforced inlet valves

At the top of the rev range, the F20C inlet valve opens and closes several dozen times in a single second to fill the cylinder with fresh air. Each return slaps it onto its seat, while the stem slides without pause through the guide. It is measured between 400 and 550 °C, a band in which standard chrome-silicon steel is already struggling: 500 MPa at 500 °C, then just 250 MPa at 600 °C, just beyond, 50 % less strength. Sharper cams, higher spring rates, raised revs or forced induction make the impacts, rubbing wear and heat even worse.

At SUPERTECH, the valve is made of a racing stainless akin to EV8, keeping 650 MPa at 500 °C and 550 MPa at 600 °C, that is 30 % then 120 % better than stock steel; black nitriding hardens and polishes the stem, which wears less in the guide. FERREA offers two series for this engine: Competition Plus, whose stainless body gets a chromed stem and which holds 20 % better in heat and fatigue while sparing the seat 25 % longer, and the 6000 series, EV8 stainless finished with a hard-chromed stem. Three finishes are thus available on the S2000, from road to track.

Two oversizes exist, with unchanged stem and length: +0.5 mm (36.5 mm head, SUPERTECH) and +1 mm (37.0 mm head, SUPERTECH and Competition Plus). The enlarged head widens the opening at the seat; each cylinder draws in more and power rises, once the inlet seats are cut to size.

Inlet valve technical specification

HIVN-1030F-8: flat head, undercut stem under the head and back cut; HIVN-1033F-8: flat head.
FERREA: valves intended for the S2000 F20C (2000-2003) and F22C (2004-2008).

Fitting details

The +0.5 mm and +1 mm sizes need the inlet seats cut to 36.5 mm or 37.0 mm, a workshop job to plan with the cylinder head rebuild.

The F20C valve clearance is set by screws on the rocker arms: once the valves are replaced, check it and reset it to the manufacturer's values.

Technical guide

Our brands

	SUPERTECH Performance, a Californian maker from San Jose, has produced competition valves, springs and retainers for more than three decades. Each part number, studied cylinder head by cylinder head, goes through ultrasound, radiography and laser checks, after which engine builders approve it.
	FERREA Racing Components started in 1978 in Fort Lauderdale, a Florida city, thanks to two Argentine tuners, and keeps its manufacturing in house. Its valves, forged as one block from bar and then machined entirely on CNC, are found in NASCAR and in drag racing.

How to choose

Under the retainer, the collets sit in the stem notch and lock the valve. On the S2000, you choose head size and material, which set what you gain.

When reinforced valves become necessary

• Higher camshaft lift or uprated valve springs
• Fuel cut-off rev limit raised
• Supercharger or turbo added
• Head rebuilt for circuit, hillclimb or rally
• Damaged, worn or already reground original valves

Compatible vehicles

OEM part number (inlet valve): 14711-PCX-000 (F20C)

Related products

Rebuilding an S2000 head also means renewing the exhaust side and every valve stem seal. Both engines' exhaust valves are grouped on this page: