Reinforced inlet valves PEUGEOT 306 S16 405 XU10J4

PEUGEOT engines covered

The XU10J4 is the PSA 2.0 litre four with 16 valves and twin camshafts that powers the Peugeot 306 S16 from 1994 to 2001, as a 5-door and as a 4-door saloon, and the 405 II 2.0 16V from 1992 to 1999, with 150 to 158 hp.

Its head carries 8 inlet valves, two per cylinder. On an S16 built for track or rally, more revs and sharper camshafts put them through far more heat and impact than original use.

SUPERTECH reinforced inlet valves

Opened by its cam, the inlet valve lets the mixture into the cylinder, then comes back to beat against its seat on every cycle, with the stem sliding against its guide. In its 400 to 550 °C range, ordinary chrome-silicon steel holds 500 MPa at 500 °C but falls to 250 MPa at 600 °C, 50 % of its strength lost. An engine pushed higher up the rev range adds to this stress.

SUPERTECH shapes it from a chrome-nickel stainless steel for competition, related to EV8 (21-4N), holding 650 MPa at 500 °C, 30 % above the stock part, and 550 MPa at 600 °C, 120 % better. Black nitriding hardens its surface, and its flat head comes in a +0.5 mm oversize: 34.6 mm, with a 6.98 mm stem and a 106.4 mm length.

Inlet valve technical specification

PEIVN-28055F-8: set of 8 flat head valves.

Fitting details

No reinforced collets, valve stem seals or valve guides are listed for the XU10J4: the original PSA parts are refitted, preferably new.

With its 34.6 mm head at +0.5 mm oversize, the valve needs inlet seats cut to this dimension.

Technical guide

The brand offered

Born in the San Jose area of California, SUPERTECH has produced racing valves and valvetrain parts for over thirty years. Every design starts from a drawing dedicated to the engine, goes through ultrasound, radiography and laser, then is proven by competition tuners.

How to choose

The XU10J4 has just one part here: its head, 0.5 mm larger, sets the seat machining to plan and the gain in flow over the valve fitted by PSA.

When reinforced valves become necessary

• Camshafts with more lift or uprated valve springs
• Cut-out speed raised
• Forced induction fitted to the XU10J4
• S16 head redone for track, rally or hill climb
• Worn or marked original valves, or seats reground once

Compatible vehicles

Don't forget the exhaust valves

A restored S16 cylinder head deserves new valves on both sides; the reinforced exhaust valves designed for the XU10J4 can be found here: