Reinforced valve spring kit Subaru Toyota FA24

€1,355.02 (tax incl.)

Reinforced valve spring kit of 16 springs for the FA24 2.4 engine of Subaru and Toyota.

Brand: FERREA
Engines: FA24 2.4 (BRZ, GR 86)
Springs: double
Contents: springs, upper retainers, lower spring seats, collets

The Subaru and Toyota FA24 engine

The FA24 is the 2.4 litre, 16-valve, flat-four engine of Subaru, fitted to the BRZ and to the Toyota GR 86.

The kit replaces the standard spring with its upper retainer, lower spring seat and collets; the box holds each part in the quantity needed for the engine's sixteen valves.

FERREA reinforced valve spring kit

When the cam releases the valve, the spring has to push it back onto its seat. At high revs inertia holds it up: without enough load it bounces, closes late and may touch the piston. The valve is then said to float.

Here each valve gets a double spring, two springs nested together that split the effort and limit vibration better.

Valve spring kit technical specification

Part number	Brand	Springs	Outer / inner Ø	Seat pressure	Open pressure	Rate	Max lift	Kit contents
KT4063	FERREA	Double						16 springs, 16 upper retainers, 16 lower spring seats, 16 collets

Valve spring kit fitting details

Part	Subaru original	Reinforced spring kit
Spring		Kit specific: S10192
Retainer		Kit specific: E20065
Spring seat		Kit specific: SL1200
Collets		Kit specific: K10094

The KT4063 gathers 16 double springs S10192, 16 upper retainers E20065, 16 lower spring seats SL1200 and 16 collets K10094, the whole fixing of each spring.

For installed height, valve closed, measure between the spring's two bearing points: the lower seat that carries it and the retainer that covers it. The load is only exact for one given height. The longer that dimension gets, after a head skim for instance, the lower the load falls, by the rate for every millimetre. Measure every valve before fitting.

	FERREA
Installed height
Seat pressure at this height

Technical guide

Our brands

FERREA has been based in Florida since 1978. It designs and machines its own valves, springs, retainers, tappets and roller rockers, meant for racing as much as for modified road cars. Its kits bring springs, retainers and collets together.

How to choose

Firmer springs keep each valve riding its cam in the revs where the stock part would let go: limiter pushed back, livelier cam profile, turbo pushed harder. Stay close to the real need all the same, since springs that are too hard wear cams and tappets early. Here the double coil spreads the effort over two springs rather than concentrating it on one, which spares the valvetrain.

Criterion	Key point
Choosing the pressure	Three things decide the right load: how far the camshaft lifts the valve, the engine speed you are aiming for and the boost you run. Going past what is needed brings no gain and tires the valvetrain sooner. Measure the height of the new spring before fitting the assembly, valve by valve. A camshaft with moderate lift and modest revs get by with a lighter load.
Single or double spring	Two springs nest on each valve, one inside the other: the effort is split between them and oscillations die down. The solution calls for a more involved fitting than a single spring, which explains the retainers and collets supplied with the kit for each of the sixteen valves.

When reinforced springs become necessary

Camshaft livelier than the stock one
Rev limiter pushed back by the tuner
Larger turbo or raised boost pressure
Head reworked for track or competition use
Tired springs, valves floating before the limiter

Compatible vehicles

Model	Engine code	Power	Years
Subaru BRZ	FA24
Toyota GR 86	FA24

Important: this kit is for the 2.4 litre FA24 engines, identified by their code. The 2.0 litre FA20 engines are not covered, even when the model is the same.