Reinforced inlet valves TOYOTA 1JZ-GE 1JZ-GTE

TOYOTA engines covered

The 1JZ is Toyota's 2.5 litre straight six with 24 valves, twin overhead camshafts and shim adjustment. The naturally aspirated 1JZ-GE and the turbocharged 1JZ-GTE power the Chaser, Cresta, Crown, Mark II, Soarer, Verossa and the JZA70 Supra, from 1988 to the mid-2000s.

Its cylinder head carries 12 inlet valves: original part numbers 13711-46020, 13711-46021 then 13711-46022 on the 1JZ-GE, 13711-88400 then 13711-88410 on the 1JZ-GTE. Raised boost, sharper camshafts or drift and track use expose them to more heat and harder impacts.

SUPERTECH reinforced inlet valves

Each inlet valve opens the way for fresh air, closes by striking its seat and slides in its guide, at a temperature of 400 to 550 °C. In that zone, the chrome-silicon steel of common valves drops from 500 MPa at 500 °C to 250 MPa at 600 °C: half of its strength is gone, 50 %.

Both SUPERTECH part numbers are black nitrided, which hardens the stem surface and reduces wear in the guide; the stem is undercut below the head and the head is back cut to ease the air flow.

The TIVN-1009-12 takes the head from 32 to 33 mm, with stem and length unchanged: air goes through a wider area, the cylinder fills better and the engine gains power, once the 12 inlet seats are machined to that diameter.

Inlet valve technical specification

Fitting details

These valves have a single groove: they are fitted with 6 mm single groove collets, such as the KPR-6T-ST, which grip the stem firmly.

The 33 mm TIVN-1009-12 needs inlet seats machined to its size; the 32 mm TIVN-1008-12 fits on seats that are simply reground.

Valve clearance is set with shims: after replacing the valves, check it and adjust the shims.

Technical guide

The brand offered

A Californian racing valvetrain specialist for more than thirty years, SUPERTECH Performance machines valves, springs and guides and puts every batch through ultrasound, X-ray and laser checks.

How to choose

The groove is the notch machined at the end of the stem, where the collets that hold the retainer sit. On the 1JZ, both sets have a single groove; the choice is made on the size:

When reinforced valves become necessary

• Raised boost or bigger turbo
• Higher lift camshafts or stiffer springs
• Higher rev limit
• Cylinder head rebuilt for drift, track or drag racing
• Worn original valves or seats already reground

Compatible vehicles

OEM part number (inlet valve): 13711-46020 / 13711-46021 / 13711-46022 (1JZ-GE), 13711-88400 / 13711-88410 (1JZ-GTE)

Related products

With the 1JZ cylinder head off, replace its 12 exhaust valves as well: