Reinforced exhaust valves Peugeot 106 S16 Citroën Saxo 16V TU5J4

Peugeot and Citroën engines covered

The TU5J4 is the 1.6 litre 16-valve engine of the Peugeot 106 S16, built from 1996 to 2004 as the NFX with 118 then 120 hp: a naturally aspirated four-cylinder that likes to rev.

The 16-valve Citroen Saxo, as the 120 hp 1.6 16V and then the 118 hp VTS, uses the TU5J4 from 1996 to 2004: a naturally aspirated twin-cam 1.6 litre known for its top-end pull on rally stages and on the road.

It has 8 exhaust valves, two per cylinder, with a 6 mm stem; in sporting use they spend long periods in contact with very hot burnt gases.

FERREA, SUPERTECH and CATCAMS reinforced exhaust valves

Each time it opens, the exhaust valve sits in the burnt gases: the metal of its head reaches 760 to 870 °C on a naturally aspirated engine, over 1,000 °C when turbocharged. About 75 % of the heat leaves through the seat and 20 % through the guide. An EV8 family steel holds 550 MPa at 600 °C and only 300 MPa at 800 °C: the head fatigues, distorts and sealing drops.

FERREA supplies valves from its 6000 series in EV8 stainless steel, in standard size and with an enlarged head. SUPERTECH offers a black nitrided stainless steel valve and an Inconel valve, a nickel base superalloy that keeps 860 MPa at 732 °C and 554 MPa at 816 °C, about 85 % more than EV8 family steel around 800 °C. CATCAMS completes the range with two valves, one of 24.5 mm and one of 26 mm with an enlarged head.

The F6760 keeps the stem and length of the F6758 but its head grows from 24.56 to 25.56 mm: burnt gases leave faster and the engine gains power; the exhaust seats are machined to this size.

Exhaust valve technical specifications

The FERREA and SUPERTECH valves have a 5.96 mm stem and a 104.4 mm length; the CATCAMS valves a 6 mm stem and a 104.2 mm length.

Valve fitting

Check the collets on reassembly: they must be sound and held firmly in the stem groove.

The stem slides in the guides: check their clearance and replace the valve stem seals during the rebuild.

The exhaust seats are reground with the new valves; with the 25.56 mm F6760 or the 26 mm 9249006M they are machined to the new size.

Technical guide

Our brands

	SUPERTECH, an American maker of racing valvetrain parts, offers two exhaust valves with a 24.5 mm head for the TU5J4: one in black nitrided stainless steel and one in Inconel, the most heat resistant on this page.
	FERREA, another American specialist, supplies two valves from its 6000 series in EV8 stainless steel: the F6758 in standard size (24.56 mm) and the F6760 with a head enlarged by 1 mm (25.56 mm).
	CATCAMS, a European maker of camshafts and valvetrain parts, offers two exhaust valves with a 6 mm stem for this engine, with a 24.5 mm or a 26 mm head (1.5 mm oversize).

How to choose

The choice depends on head size and material:

When reinforced valves become necessary

• More aggressive camshafts
• Track, rally or hill climb use
• Marked or leaking exhaust valves
• Cylinder head rebuild

Vehicle compatibility

OEM part number (exhaust valve):

Don't forget the inlet valves

With the TU5J4 cylinder head open, also change the inlet valves and the valve stem seals.