Reinforced inlet valves HONDA D16Y D16Z6 D17A

HONDA engines covered

The D16Y, D16Z6 and D17A make up Honda's single overhead camshaft, 16-valve D series: 1,590 cc for the D16, 1,668 cc for the D17A, with or without VTEC depending on version. They are found in the Civic V to VII, the CRX III, the Jazz II, the Stream and the FR-V, from 1991 to 2007.

Each engine has 8 inlet valves, two per cylinder, held on the D17A5 by Honda 14781-PJ7-003 collets. Sharper camshafts, stiffer springs, a higher rev limit or a turbo work them well beyond stock use.

SUPERTECH and FERREA reinforced inlet valves

The inlet valve opens the way for fresh air dozens of times per second at high revs, strikes its seat at every closing and slides constantly in its guide. It runs between 400 and 550 °C, where the original chrome-silicon steel falls from 500 MPa at 500 °C to 250 MPa at 600 °C, 50 % of its strength lost.

SUPERTECH valves are made from a racing stainless steel of the EV8 family, which keeps 650 MPa at 500 °C and 550 MPa at 600 °C, 30 % and then 120 % more than the original steel. Black nitriding makes the surface harder and smoother: the stem rubs and wears less in the guide. FERREA offers three series for these engines: Competition Plus, 20 % stronger when hot and under fatigue, with a seat lasting 25 % longer, then the 6000 and 5000 Series.

Two oversizes exist besides the 30.0 mm standard size: +0.5 mm (30.5 mm head) and +1 mm (31.0 mm head), stem and length unchanged. The wider head lets more air in and improves filling, provided the inlet seats are cut to the new size. At FERREA, each series comes in the 30.0 mm standard size and as +1 mm (31.0 mm), with a 118.6 mm length.

Inlet valve technical specification

HIVN-1102-8: dished head, for the D16Z6, D16Y8 and D17.
FERREA: part numbers for the D16Z6, D16Y7 and D16Y8 of this page.

Fitting details

The +0.5 mm and +1 mm oversizes require inlet seats cut to 30.5 or 31.0 mm, workshop work to plan with the cylinder head rebuild.

Valve clearance is adjustable on these engines: after replacing the valves, check and adjust it (0.18 to 0.22 mm cold on the inlet side for the D16Y, D16Z6 and D17A).

Technical guide

Our brands

	SUPERTECH works out of San Jose, California, and has supplied valvetrain parts for racing engines for more than 30 years: valves, springs, retainers and guides. Each part number starts from a specific cylinder head, goes through ultrasound, X-ray and laser checks, then is proven with engine builders, from drag strip to circuit.
	FERREA Racing Components took root in 1978 in Fort Lauderdale, Florida, around two Argentine engine tuners. The company forges its valves in one piece from bar stock, machines them entirely on CNC and proves them in NASCAR and drag racing engines.

How to choose

The size depends on the condition of the inlet seats in the cylinder head and the airflow gain wanted.

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

OEM part number (inlet valve): 14711-P08-000 (D17A5)

Related products

A rebuilt D-series or R18 cylinder head also gets new exhaust valves. They are available here: