Reinforced inlet valves CITROËN AX Sport TU24

CITROËN engines covered

The TU24 is the sporting version of PSA's 1.3 litre (1,294 cc) four-cylinder with two valves per cylinder. It powers the Citroën AX Sport from 1987 to 1988, with 95 hp.

Its cylinder head has 4 inlet valves, one per cylinder, with an 8 mm stem. A peaky engine, widely used in rallying and hillclimbs, it works its valves hard at high rpm.

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 9249010M for this engine, supplied here as a set of 4: 39.3 mm head, 8 mm stem and 111.3 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 offers the valves, springs and retainers that suit its profiles, for small rally engines as well as circuit engines.

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