Reinforced exhaust valves Lexus GS430 LS430 SC430 3UZ-FE

Lexus engines covered

The 3UZ-FE is the 4.3 litre, 32-valve V8, always fitted with VVT-i variable valve timing, that powers the Lexus GS 430, LS 430 and the SC 430 convertible.

Its 16 exhaust valves carry original part number 13715-50070, which follows 13715-50060, with a 5.465 to 5.480 mm stem. On these long-distance cruisers, they endure long journeys at sustained speed in contact with burnt gases.

SUPERTECH reinforced exhaust valves

On a naturally aspirated engine, an exhaust valve head rises to 760 to 870 °C; forced induction takes it beyond 1,000 °C. Nearly 75 % of the heat leaves through the seat and around 20 % through the guide. An EV8 family steel withstands 550 MPa at 600 °C, then falls to 300 MPa at 800 °C: the head fatigues and distorts, and the valve seals less well.

Cut from Inconel, a nickel-based superalloy, the TEVI-1093D-16 keeps 860 MPa at 730 °C and 554 MPa at 815 °C: nearly 85 % more strength than EV8 steel around 800 °C. The head is dished.

At 30.5 mm, its head is 1.5 mm larger than the standard size: the cylinder empties its burnt gases faster and fills better. The exhaust seats are machined to this size before fitting.

Exhaust valve technical specifications

TEVI-1093D: 30.5 mm dished head (+1.5 mm), 5.47 mm stem, 95.1 mm length, Inconel.

Valve fitting

When fitting, the 90913-03028 collets must sit correctly in the groove of each stem.

The 16 exhaust seats of both cylinder heads are recut to take the 30.5 mm head.

Use all 16 valves from one set and take the opportunity to renew the exhaust valve stem seals.

Technical guide

Our brand

SUPERTECH Performance has been designing racing valves and valvetrain parts in California for more than thirty years. For the 3UZ-FE V8, the brand offers a dished-head Inconel exhaust valve, 1.5 mm oversize.

How to choose

This engine has only one version:

When reinforced valves become necessary

• Fitting a supercharger or a turbo (Inconel version recommended)
• Track use or sustained high-rpm driving
• Sharper camshafts
• Cylinder heads rebuilt after burnt exhaust valves

Vehicle compatibility

OEM part number (exhaust valve): 13715-50070 (supersedes 13715-50060)

Don't forget the inlet valves

Once the 3UZ-FE cylinder heads are off, remember to change the inlet valves and the valve stem seals too.