Reinforced exhaust valves Nissan Patrol TB48DE

Nissan engines covered

The TB48DE is Nissan's 4.8 litre 24-valve inline six fitted to the Patrol GR V Y61 since 2000 and, depending on the market, to the Patrol VI Y62.

Its cylinder head carries 12 exhaust valves, two per cylinder, Nissan part number 13202-VC200. SUPERTECH offers them with a 6.95 mm stem and a 98.3 mm overall length.

SUPERTECH reinforced exhaust valves

An exhaust valve stays immersed in hot gases: its head reaches 760 to 870 °C without forced induction and passes 1,000 °C with a turbo or supercharger. The seat removes about 75 % of that heat, the guide about 20 %. EV8 family steel, used as the reference for the original, loses nearly half its strength between 600 °C (550 MPa) and 800 °C (300 MPa): beyond that, the head fatigues and distorts.

The NEVN-3470F-12 is in black nitrided stainless steel, a treatment that hardens the surface and limits stem wear in the guide; its stem is undercut below the head and its head is flat.

SUPERTECH lists it at +1.5 mm, a 34.8 mm head: burnt gases leave more freely, provided the 12 exhaust seats are machined to that diameter.

Exhaust valve technical specifications

SUPERTECH note: the NEVN-3470F is listed as "34.80 (+1.5mm)", "Flat Face" and "undercut" for the Patrol TB48DE I6 24v.

Valve fitting

Before reassembly, check that the collets used match the groove of the NEVN-3470F-12.

With a 34.8 mm head, the 12 exhaust seats are machined to the new size before fitting.

The 12 valves of the set share the same 6.95 mm stem and the same 98.3 mm length.

Technical guide

Our brand

SUPERTECH Performance, a Californian maker of racing valves and valvetrain parts for more than thirty years, offers the TB48DE a flat head black nitrided stainless steel exhaust valve at +1.5 mm.

How to choose

A single part number is offered for this engine:

When reinforced valves become necessary

• Supercharger or turbo added
• More aggressive camshafts
• Heavy off-road or towing use
• Cylinder head rebuild with tired exhaust valves
• Enlarged seats to improve flow

Vehicle compatibility

OEM part number (exhaust valve): 13202-VC200

Don't forget the inlet valves

A TB48DE cylinder head off the engine is the right time to check the inlet valves and the valve stem seals as well.