Reinforced inlet valves CITROËN BX 16V XU9J4

CITROËN engines covered

At Citroën, the XU9J4, PSA's 1.9 litre (1,905 cc) 16-valve four-cylinder, powers the BX 19 GTi 16V from 1987 to 1993, with 147 to 158 hp, then the BX 1.9 GTi from 1992 to 1993, with 160 hp.

Its cylinder head carries 8 inlet valves, two per cylinder, with a 7 mm stem. Often entered in rallies, the 16-valve BX runs this engine high and long, which wears the original valves.

CATCAMS reinforced inlet valves

The inlet valve opens on every cycle to let fresh air in, drops back onto its seat and slides in its guide, dozens of times per second at high rpm. It runs between 400 and 550 °C; in this range the original chrome-silicon steel drops from 500 MPa at 500 °C to 250 MPa at 600 °C and loses 50 % of its strength.

CATCAMS offers the 9249012M for this engine, supplied here as a set of 8: 34.6 mm head, 7 mm stem and 106.5 mm overall length.

Inlet valve technical specification

Fitting details

On reassembly, check that the collets match the groove of the valves.

Technical guide

The brand offered

A European maker of racing camshafts, CATCAMS also supplies the valves, springs and retainers that go with its profiles on tuned engines, from road to rally.

How to choose

The groove is the recess cut at the end of the stem, where the collets hold the upper retainer. A single part number is offered for this engine:

When reinforced valves become necessary

• Sharper camshaft or stiffer springs
• Higher rev limit
• Turbocharger or supercharger fitted
• Cylinder head rebuilt for rallying, hillclimb or circuit
• Worn original valves or seats already reground

Compatible vehicles