Reinforced exhaust valves Nissan Skyline GT-R RB26DETT

Nissan engines covered

The RB26DETT is the 2.6 litre twin-turbo, 24-valve inline six of the Skyline GT-R R32, R33 and R34, also used in the Stagea 260RS.

Its cylinder head carries 12 exhaust valves; the SUPERTECH valves have a 6.94 mm stem. The two turbos at the manifold outlet and the high boost sought in tuning put them under heavy strain.

SUPERTECH and FERREA reinforced exhaust valves

With the turbos loaded, the metal of the exhaust head goes beyond 1,000 °C, against 760 to 870 °C on a naturally aspirated engine. About 75 % of the heat leaves through the seat, 20 % through the guide. An EV8 family steel is the benchmark for the original part: 550 MPa at 600 °C, 300 MPa at 800 °C. As boost rises, the head fatigues, warps and ends up leaking at the seat.

SUPERTECH supplies Inconel, a nickel-based superalloy that keeps 860 MPa at 732 °C and 554 MPa at 816 °C, about 85 % more than the original steel around 800 °C, in solid form (NEVI-1032-7, NEVI-1032-7-L) and sodium-filled (NEVI-1032-7-HS), which helps move heat from the head to the stem. FERREA offers its Super Alloy, a nickel-based superalloy intended for turbo applications, from the Competition Plus range, with 20 % more hot strength and 25 % longer seat life.

The +1 mm versions take the head from 30.15 to 31.15 mm: the burnt gases leave faster and scavenging improves, by about 10 to 12 cfm of flow per millimetre of head. The 12 exhaust seats are then machined to that diameter.

Exhaust valve technical specifications

Valve fitting

The SUPERTECH valves on this page have a single groove: they are fitted with single groove collets, to be compared with the collets you reuse before refitting the springs.

The NEVI-1032-7-L has a stem tip 1.5 mm longer: the original retainer is not suitable, it is fitted with the RET-NRB60/TS-2 retainer.

At 30.15 mm (FERREA F2131P) the seats are left as they are; with a +1 mm version, the 12 exhaust seats are cut to 31.15 mm.

Technical guide

Our brands

	SUPERTECH Performance, in California, has made racing valves for more than thirty years. For the RB26DETT it offers Inconel in +1 mm, solid, sodium-filled or with a longer tip.
	FERREA, founded in 1978, produces its valves in Florida and Argentina. For the RB26DETT it offers its Super Alloy for turbo applications, in standard size and +1 mm.

How to choose

The choice comes down to size, material and length:

When reinforced valves become necessary

• Increased boost pressure
• Larger turbos
• E85 fuel or high power
• Track days
• Cylinder head rebuild with marked exhaust valves

Vehicle compatibility

OEM part number (exhaust valve): 13202-05U01

Don't forget the inlet valves

An RB26DETT cylinder head on the bench is the right time to replace the inlet valves and the valve stem seals as well.