Reinforced exhaust valves Peugeot 306 S16 405 XU10J4

Peugeot engines covered

The XU10J4, Peugeot's 16-valve 2.0, powers the 306 S16 (types 7A, 7B, 7C, N3, N5) from 1994 to 2001 and the 405 II (4B) 2.0 16V from 1992 to 1999.

It has 8 exhaust valves. The reinforced valve has a 29.6 mm head, a 6.96 mm stem, a 104.9 mm overall length and a 4.4 mm tip.

SUPERTECH reinforced exhaust valves

In the XU10J4 cylinder head, the 8 exhaust valves see the gases pushed out by the pistons at every cycle. Without a turbo their head stays between 760 and 870 °C; forced induction would take it past 1,000 °C. The seat alone drains about 75 % of this flow, the guide about 20 %. As the yardstick for the original valve, EV8-family steel falls from 550 MPa at 600 °C to 300 MPa at 800 °C; held near the red line of a 306 S16 for long, the head overheats, wears, warps and no longer closes properly.

SUPERTECH's PEEVI-28056F-8 comes out of Inconel, a nickel superalloy whose strength reaches 860 MPa at 732 °C and 554 MPa at 816 °C, around 85 % better than EV8 near 800 °C: a safety margin for a four-cylinder that often works at full load.

Its 29.6 mm head sits on a 6.96 mm stem, for a 104.9 mm length and a 4.4 mm tip. The 8 exhaust seats are refaced to 29.6 mm on reassembly, to restore a clean contact and a good seal.

Exhaust valve technical specifications

Valve fitting

Before reassembly, check that the collets suit the lock groove of the PEEVI-28056F-8.

With a 29.6 mm head, the exhaust seats are cut to that diameter.

Technical guide

Our brand

SUPERTECH Performance has built its name in California over 30-plus years of valves and valvetrain parts: springs, guides, titanium retainers. Whether the job calls for Inconel, titanium or stainless, each valve matches one engine and is fine-tuned together with drag and rally specialists.

How to choose

For the XU10J4 of the 306 S16 and 405 2.0 16V, the range comes down to one valve: the PEEVI-28056F-8, in Inconel, with a 29.6 mm head. So the choice simply means checking the seats, which are refaced to this diameter:

When reinforced valves become necessary

• Turbo or supercharger conversion on the XU10J4 (Inconel advised)
• Sharper cams or stiffer springs
• Circuit, rally or hillclimb use in a 306 S16
• Exhaust valves worn out, pitted or leaking at the seat
• Complete cylinder head rebuild on a 306 or a 405

Vehicle compatibility

OEM part number (exhaust valve):

Don't forget the inlet valves

With the XU10J4 head stripped, it is the moment to replace the inlet valves too, with new stem seals on all 16 valves. The matching part for this four-cylinder: