Reinforced inlet valves NISSAN GT-R VR38DETT

NISSAN engines covered

The VR38DETT is Nissan's 3.8 litre 24-valve V6 with four overhead camshafts and two turbos, hand-assembled for the GT-R R35. From 480 hp at the GT-R launch in 2007, it rose year after year to 608 hp, with the NISMO version rated at 600 hp from 2014.

The engine has 12 Nissan 13201-JF00A inlet valves, held by 13210-53Y00 collets under 13209-AC700 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 EV8 stainless steel, which keeps 650 MPa at 500 °C and 550 MPa at 600 °C, 30 % and then 120 % more than the original steel. Black nitriding hardens the stem surface and makes it smoother, for lasting movement in the guide.

SUPERTECH offers them in standard size (37.15 mm head) and in +1 mm oversize (38.15 mm head), with a 5.97 mm stem and a 95.00 mm length. 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

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

Fitting details

The +1 mm size requires the inlet seats to be cut to 38.15 mm, workshop work to plan with the cylinder head rebuild.

Valve clearance on the VR38DETT is set with calibrated tappets: after replacing the valves, check the clearance and change the tappets where needed.

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.

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-JF00A