Reinforced exhaust valves Renault Clio RS F4R

Renault engines covered

The F4R is Renault's 2 litre, 16-valve four-cylinder; its F4R 730, 736 and 738 versions power the Clio II RS from 2000 to 2009, the F4R 830 and 832 the Clio III RS from 2006 to 2014.

It has 8 exhaust valves, two per cylinder. The original valve (7701 474 286, superseded by 7701473101 and 13202-00QAE) has a 29 mm head and a 5.5 mm stem; these high revving engines expose it to strong heat.

CATCAMS and SUPERTECH reinforced exhaust valves

The F4R of the Clio RS revs high and for long periods, and its exhaust valve takes the flow of gases leaving the chamber every time it opens. Measured in the alloy, head heating reaches 760 to 870 °C on this unboosted unit; forced induction would push it beyond 1,000 °C. The seat dissipates about 75 % of that heat and the guide nearly 20 %. The yardstick chosen for the original, the EV8 steel family, falls from 550 MPa at 600 °C to 300 MPa at 800 °C. Higher revs, heavier load or forced induction: the head climbs further in temperature, wears through fatigue, distorts and seat sealing worsens.

The reinforced versions rely on a material that copes better with heat. SUPERTECH makes its REVI-28338F in Inconel; this nickel-rich alloy keeps 860 MPa at 730 °C and still 554 MPa near 815 °C, about 85 % more strength than EV8 steel around 800 °C: a comfortable margin for a tuned F4R or one often run at full load. CATCAMS for its part supplies the 9255002M, whose 29 mm head and 5.5 mm stem match factory dimensions, as a set of 8 to equip the whole engine. The choice therefore sets the superior heat resistance of one against the dimensional faithfulness of the other.

The REVI-28338F-3 keeps the stem and length of the -2, but its head grows from 29 to 30 mm. The exhaust clears sooner, breathing in becomes easier and the F4R gains power. Exhaust seat machining to 30 mm then becomes necessary.

Exhaust valve technical specifications

The three sets share a 108.9 mm length; they differ by head, stem and material.

Valve fitting

The 9255002M is fitted with LK5.5 collets; with the SUPERTECH valves, check that the collets seat properly in the groove before releasing the springs.

The original guides (7700 109 151) are checked during the rebuild; replace the valve stem seals (7700103938) at every reassembly.

The exhaust seats are reground during the rebuild; with the 30 mm head they are machined to that size.

Technical guide

Our brands

	SUPERTECH, founded in California, has worked for over 30 years in Silicon Valley for racing engines: valves and springs, guides, and retainers cut from titanium. Every valve, in Inconel, stainless steel or titanium, is designed for one engine and approved by demanding tuners.
	CATCAMS, a Belgian manufacturer, designs its own profiles and grinds its camshafts under numerical control. Tappets, adjusting shims, valve springs and retainers complete the offer; its camshafts have run in British touring cars and at the 24 Hours of Le Mans.

How to choose

The retainer bears down on the collets, which secure the valve firmly. On the F4R, every single version measures 108.9 mm: so you weigh up two head sizes, which determine the seat work, and then two brands.

When reinforced valves become necessary

• New high-lift camshafts, firmer springs
• Fuel cut moved up to rev higher
• Turbo or supercharger grafted onto the F4R (Inconel version recommended)
• Frequent track, rally or hill climb outings
• Head overhaul because of worn or pitted exhaust valves

Vehicle compatibility

OEM part number (exhaust valve): 7701 474 286 = 7701473101 = 13202-00QAE

Don't forget the inlet valves

With the F4R cylinder head on the bench, it is worth renewing the inlet valves too, along with brand new valve stem seals. The Clio RS inlet valves are offered here: