Reinforced inlet valves HONDA L15A LEA

HONDA engines covered

The L15A and its LEA1 hybrid version, paired with the IMA electric motor of the CR-Z, are Honda 1,497 cc 16-valve four-cylinders, from 90 to 132 hp. They are found in the Airwave, City V, Freed, Jazz Shuttle, Mobilio and CR-Z, from 2001 onwards.

Each engine has 8 inlet valves, two per cylinder. A sharper camshaft, stiffer springs, a higher rev limit or forced induction ask far more of them than stock use.

SUPERTECH 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.

SUPERTECH supplies it in the engine's standard size: 28.0 mm head, 5.48 mm stem, 118.85 mm length.

Inlet valve technical specification

HIVN-1050-8: dished head, undercut stem under the head, back cut and 5.40 mm stem tip.

Fitting details

Technical guide

The brand offered

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.

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 L15A cylinder head, the reinforced exhaust valves are available here: