Reinforced valve spring kit Porsche 996 M96.03 M96.70

The Porsche engines covered

This kit is made for the 3.6 litre, 24-valve flat-six of the Porsche 911 type 996, in its two versions: the naturally aspirated M96.03 of the Carrera models, 320 to 345 hp, and the boosted M96.70 of the 996 Turbo and GT2, 420 to 483 hp, built from 2000 to 2005.

FERREA asks for the original lower spring seats to be removed and replaced by the ones in the kit. The original upper retainers and collets also give way to the kit parts, with titanium upper retainers. The SUPERTECH kit also supplies its own upper retainers and lower spring seats.

FERREA and SUPERTECH reinforced valve spring kits

As the lobe fades away, the spring must seat the valve again at once. As revs build, inertia takes charge: the valve bounces, leaves the cam and may reach the piston, a case of valve float.

The FERREA kit brings 24 double springs, two nested springs per valve: 436 N on the seat at 33.5 mm, then 979 N at 9.0 mm lift. The SUPERTECH kit SPRK-1002D-M96 also brings 24 double springs: 329 N (74 lbs) on the seat at 33.4 mm, then 805 N at 10.0 mm lift.

Valve spring kit technical specification

Valve spring kit fitting details

The FERREA KT4034 kit holds 24 S10122 double springs, 24 E11094 titanium upper retainers, 24 SL1099 lower spring seats and 24 K10092 collets. The original lower spring seats are not reused. The SUPERTECH kit SPRK-1002D-M96 holds 24 SPR-H1002D double springs, 24 RET-K20A2/T3 upper retainers and 24 SEAT-H1002-S14 lower spring seats.

Installed height is the distance separating, valve closed, the base of the spring on its lower spring seat and the underside of the upper retainer. The 436 N load is quoted for 33.5 mm; any higher, it drops by the spring rate for each added millimetre (see above). FERREA lift is also capped at 11.2 mm, because the upper retainer then comes close to the valve stem seal.

Technical guide

Our brands

	FERREA opened its workshops in Florida in 1978, started by engine builders who came from Argentina. The brand makes its own valves, springs, retainers and tappets, and its parts run in NASCAR as well as in drag racing and on the track, from retainers to springs.
	SUPERTECH is a California maker whose valve springs have been fitted to racing engines for more than thirty years. Before shipping, every series of springs goes through laser, ultrasonic and X-ray checks, to rule out any internal flaw, even one invisible to the naked eye.

How to choose

Raising the spring load lets an engine reach higher revs, accept a sharper camshaft or run more turbo pressure while the valves keep following the cam. This FERREA kit delivers 436 N on the seat and 979 N at 9.0 mm lift. Check how high your camshafts actually lift before ordering: with the FERREA kit, past 11.2 mm the upper retainer no longer clears the valve stem seal. A few minutes of measuring settles the question. The SUPERTECH kit gives 329 N on the seat and 805 N at 10.0 mm lift.

When reinforced springs become necessary

• Camshafts lifting higher than the original
• Rev limit pushed far beyond standard
• Stronger boost, turbo or supercharger
• Heads reworked for circuit, hill climb or rally
• Tired original springs or valves in float

Compatible vehicles

Related products

Cylinder heads removed? Have valves and guides checked before fitting new springs. The inlet and exhaust valves for each engine are offered below: