Reinforced inlet valves NISSAN L28

NISSAN engines covered

The L28 is Nissan's 2.8 litre 12-valve inline six with a single overhead camshaft, from 120 to 147 hp depending on version. From 1977 to 1990 it powers the Datsun 280C, the Cedric 430, the Laurel C230 and the Patrol 160 and 260.

The engine has 6 inlet valves, one per cylinder. Sharper camshafts, a higher rev limit or a race build load them well beyond stock use.

SUPERTECH reinforced inlet valves

On a tuned six-cylinder, each inlet valve opens dozens of times per second, then strikes its seat and slides 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 is gone.

SUPERTECH makes these valves 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 stem harder and smoother, so it wears less in the guide.

SUPERTECH supplies it with a 44 mm head, a 7.96 mm stem and a 116.65 mm length.

Inlet valve technical specification

SUPERTECH: dished head, undercut stem under the head and back cut.

Fitting details

Technical guide

The brand offered

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.

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