Reinforced inlet valves NISSAN RB26DETT

NISSAN engines covered

The RB26DETT is Nissan's 2.6 litre 24-valve inline six with twin overhead camshafts and two turbos, from 280 to 333 hp. It powers the Skyline 2.6 Twin Turbo 4x4 coupés R32, R33 and R34 and the Stagea 2.6 Twin Turbo estate, from 1989 to 2008.

The engine has 12 Nissan 13201-05U00 inlet valves, held by 13210-D4200 collets under 13209-05U00 retainers. Raised boost, sharper camshafts or a higher rev limit load them well beyond stock use.

SUPERTECH reinforced inlet valves

On a tuned turbo six, each inlet valve opens dozens of times per second, then strikes its seat and slides in its guide under boost pressure. 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 offers them in standard size (34.65 mm head) and in +1 mm oversize (35.65 mm head), with a 5.97 mm stem, 102.30 mm long, and 103.80 mm for the +1 mm version with a longer stem tip. On the +1 mm size, the wider head opens a larger passage at the seat: the cylinder fills better and the engine gains power, with the inlet seats cut to the new size.

Inlet valve technical specification

NIVN-1032-L-12: stem tip 1.5 mm longer; fit with the SUPERTECH RET-NRB60/TS-2 retainer, never with an original-type retainer.

Fitting details

The +1 mm size requires the inlet seats to be cut to 35.65 mm, workshop work to plan with the cylinder head rebuild.

The longer NIVN-1032-L-12 needs the SUPERTECH RET-NRB60/TS-2 retainer instead of the original 13209-05U00 retainer.

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.

How to choose

The size is chosen according to the condition of the inlet seats and the filling wanted; the length according to the retainers fitted.

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): 13201-05U00