Reinforced exhaust valves Nissan 240SX Altima KA24DE

Nissan engines covered

The KA24DE is Nissan's 2,389 cc four-cylinder (89 mm bore, 96 mm stroke) with twin camshafts and 16 valves. It powers the 240SX, the Altima, the Navara D22 and many Japanese models of the 1990s and 2000s.

It has 8 exhaust valves, two per cylinder, Nissan part numbers 13202-53F00, 13202-9E000 then 13202-0Z800 depending on the year: 31.2 to 31.4 mm head, 6.945 to 6.960 mm stem and 98.67 to 98.97 mm overall length.

SUPERTECH reinforced exhaust valves

On the exhaust side, the head metal rises to 760 to 870 °C on a naturally aspirated engine and passes 1,000 °C as soon as a turbo is involved. About 75 % of that heat goes back through the seat, around 20 % through the guide. EV8 family steel, taken as the reference for the original, drops from 550 MPa at 600 °C to 300 MPa at 800 °C: the overheated head fatigues, warps and no longer seats properly.

The NEVN-1010-8 is in black nitrided stainless steel: nitriding hardens the surface and protects the stem against wear in the guide. The NEVI-1011-8 is in Inconel, a nickel-based superalloy that keeps 860 MPa at 732 °C and 554 MPa at 816 °C, about 85 % more than EV8 steel around 800 °C.

Both part numbers have an enlarged head: +0.5 mm (31.8 mm) for the NEVN-1010-8, +0.7 mm (32.0 mm) for the NEVI-1011-8. Burnt gases leave faster and the cylinder empties better, provided the exhaust seats are machined to that diameter.

Exhaust valve technical specifications

The NEVN-1010-8 has an undercut stem below the head.

Valve fitting

Compare the original collets 13210-40F00 then 13210-D4200 with the groove of the SUPERTECH valves before reassembly.

With a 31.8 or 32.0 mm head, the 8 exhaust seats are machined to the new size before fitting.

The original valve stem seals (13207-53F00, 13207-D0111, 13207-2B500) and the 13213-53F60 exhaust guide complete the cylinder head survey.

Technical guide

Our brand

SUPERTECH Performance, a Californian maker of racing valves and valvetrains for more than thirty years, offers the KA24DE a black nitrided stainless steel exhaust valve at +0.5 mm and an Inconel version at +0.7 mm.

How to choose

The choice is made on head size and material:

When reinforced valves become necessary

• Turbo fitted (Inconel version recommended)
• More aggressive camshafts or firmer springs
• Drift or track use
• Cylinder head rebuild with worn exhaust valves
• Enlarged seats to gain flow

Vehicle compatibility

OEM part number (exhaust valve): 13202-53F00, 13202-9E000, 13202-0Z800

Don't forget the inlet valves

A KA24DE cylinder head off the engine is the right time to check the inlet valves and the valve stem seals as well.