Reinforced inlet valves NISSAN 240SX Altima KA24DE

NISSAN engines covered

The KA24DE is Nissan's 2.4 litre four-cylinder with twin overhead camshafts and 16 valves. It powers the 240SX and 200SX, the Altima L30, the Bluebird, the Presage, the D22 and Navara pickups and the Xterra, from 116 to 158 hp.

Its 8 original inlet valves, Nissan 13201-53F02, 13201-9E000 or 13201-0Z800, have a 36.5 to 36.7 mm head, a 6.965 to 6.980 mm stem and a 101.17 to 101.47 mm length. A turbo, sharper camshafts or a higher rev limit expose them to more heat and impact.

FERREA and SUPERTECH reinforced inlet valves

In a KA24DE each of the 8 inlet valves opens to let fresh air in, snaps shut against its seat and keeps sliding in its guide, cycle after cycle, thousands of times a minute at high revs. To do so it endures 400 to 550 °C. A plain chrome-silicon steel offering 500 MPa at 500 °C keeps only 250 MPa at 600 °C, just above: its strength melts away by 50 %. Adding a turbo, sharper cams or more revs increases by the same token the impacts, the frictional wear and the heat the valve must withstand.

The SUPERTECH valves are made of stainless from the EV8 family, which retains 650 MPa at 500 °C and 550 MPa at 600 °C, 30 % and then 120 % more than that steel; their black nitriding also hardens the stem surface and cuts wear against the guide. The FERREA Competition Plus valves use a special alloy rated at 20 % more heat strength and fatigue endurance, with a seat whose service life extends by 25 %, a real asset for a boosted or hard-worked engine.

Two enlarged heads are offered, leaving stem and length untouched: 37.1 mm (+0.5 mm) from SUPERTECH and 37.6 mm (+1 mm) from FERREA. With a more generous opening around the seat, air enters more easily, filling improves and power climbs, on condition that all 8 inlet seats are cut to the new dimension.

Inlet valve technical specification

Fitting details

FERREA pairs this engine with its K10062 radial groove collets, for a 7 mm stem. SUPERTECH specifies its VS-N7E valve stem seals, sold in sets of 8: one set covers the 8 inlet valves.

The 37.1 mm and 37.6 mm heads require the inlet seats to be machined to their size; the 36.6 mm valves fit seats reconditioned to factory size.

Technical guide

The brands offered

	FERREA Racing Components, established in Florida, at Fort Lauderdale, in 1978 by two Argentine tuners, handles all of its manufacturing itself. Each valve is forged as a single block from bar and finished entirely on computer-controlled machines, ready for NASCAR, drag strips or circuit racing.
	SUPERTECH Performance has focused for over three decades, in California, on competition valvetrains. Each part is conceived for one engine, checked by ultrasonic probing, radiography and laser, then developed with engine builders from the drag strip to the circuit.

How to choose

All four sets keep the KA24DE's original length: first pick the head size to suit the seats, then the brand according to the material you want.

When reinforced valves become necessary

• A turbo or supercharger bolted on
• Higher-lift camshafts or stronger springs
• Rev limiter set noticeably higher
• Head rebuilt for drift, track or rally
• Nissan valves marked or worn, or cylinder head seats already recut

Compatible vehicles

OEM part number (inlet valve): 13201-53F02 / 13201-9E000 / 13201-0Z800

Related products

KA24DE head off? Take the opportunity to replace the engine's exhaust valves too: their reinforced version is waiting for you on the page below: