Reinforced valve spring kit Mitsubishi Lancer Evolution X 4B11T

€1,394.75 (tax incl.)

Kit of 16 reinforced valve springs for the Mitsubishi 4B11T engine of the Lancer Evolution X.

Brand: FERREA
Engine: 4B11T (Lancer Evolution X)
Springs: dual
Contents: springs, titanium upper retainers, lower spring seats, collets

The Mitsubishi engine covered

This kit is made for the 4B11T, the 2.0 litre, 16-valve turbocharged four-cylinder of the Mitsubishi Lancer Evolution X (CZ4A), built from 2007 to 2014.

FERREA asks for the original lower spring seat to stay in place, with the kit part stacked on top of it. The original spring, upper retainer and collets are replaced by those of the kit, which brings a titanium upper retainer.

FERREA reinforced valve spring kit

When the cam profile falls away, the spring must press the valve onto its seat at once. Above a certain speed the valve is no longer held: it hops off the cam and can strike the piston. Builders call this valve float.

The kit holds 16 dual springs, each of two nested coils: 334 N on the seat at 36.0 mm, then 778 N after 10.0 mm of lift.

Valve spring kit technical specification

Part number	Brand	Springs	Outer / inner Ø	Seat pressure	Open pressure	Rate	Max lift	Kit contents
KT4014	FERREA	Dual	Outer 28.0 / 20.8 mm Inner 20.8 / 16.5 mm	334 N at 36.0 mm	778 N at 10.0 mm	44.5 N/mm	12.0 mm	16 springs, 16 titanium upper retainers, 16 lower spring seats, 16 collets

Valve spring kit fitting details

Part	Mitsubishi original	Reinforced spring kit
Spring	1010A201	Kit specific: S10118 (dual)
Retainer	MN183953	Kit specific: E11089 (titanium)
Spring seat		Kit specific: SL1096 (with the original seat kept)
Collets	MN183955	Kit specific: K10091

The FERREA KT4014 kit contains 16 S10118 dual springs, 16 E11089 titanium upper retainers, 16 SL1096 lower spring seats and 16 K10091 collets. The original lower spring seat stays in place under the SL1096 part.

Installed height is set with the valve closed, from the bottom bearing face of the spring to its top one. The 334 N figure is guaranteed at 36.0 mm; if the height grows, the load decreases by one spring rate per added millimetre (see above). Kit lift is capped at 12.0 mm. Measure this height on every valve before fitting.

	FERREA
Installed height	36.0 mm
Seat pressure at this height	334 N

Technical guide

Our brands

FERREA came into being in Florida in 1978, on the initiative of Argentine engine builders who had settled in the United States. Its workshops turn out valves, springs, retainers and tappets for NASCAR cars, dragsters and circuit single-seaters.

How to choose

Harder springs let an engine climb higher in the revs, take a more incisive camshaft or run more boost, with no valve float. This kit gives 334 N on the seat and 778 N at 10.0 mm lift. Before ordering, check the lift of your cams: it has to stay below 12.0 mm, the ceiling of the kit. This measurement takes only a few minutes and spares you a poorly matched purchase. The right load is the most precise one: below it the valve floats, above it parts wear faster.

Criterion	Key point
Choosing the pressure	Useful load depends on three factors: cam lift, maximum engine speed and turbo pressure. If one of them climbs, the load has to be raised while keeping lift under the limit of the kit. Here, 334 N on the seat at 36.0 mm. Extra load that nothing requires only wears the valve gear.
Single or double spring	In a dual spring, two concentric coils work together: they share the load and damp vibration better than a single coil. According to FERREA, the titanium upper retainer is 40% lighter than a steel one, which cuts the mass the spring must follow. Collets and a lower seat complete the kit.

When reinforced springs become necessary

Camshaft lifting higher than standard
Rev limit raised well above the original
Bigger turbo or raised boost pressure
Competition engine with a rebuilt head for circuit or rally
Worn stock springs, floating valves

Compatible vehicles

Model	Engine code	Power	Years
Lancer Evolution X (CZ4A) 2.0 Turbo 4WD	4B11T		2007-2014

OEM part number (valve spring): 1010A201

Important: this kit is for the Mitsubishi 4B11T engine of the Lancer Evolution X. The Hyundai Genesis Coupé 2.0 T and the naturally aspirated 4B11 are not covered here. One kit of 16 fits a complete engine.