Reinforced valve spring kit BMW S58
Kits of 24 reinforced valve springs for the BMW S58 twin-turbo six-cylinder.
- Brand: FERREA
- Engine: S58B30A (M2 G87, M3 G80, M4 G82, X3 M, X4 M, Alpina B3, B4)
- Springs: single or conical
- Contents: springs, retainers, spring seats
The BMW M S58 twin-turbo six-cylinder
The S58B30A is the 3.0-litre twin-turbo straight six of recent BMW M cars: M2 (G87), M3 (G80, G81), M4 (G82, G83), X3 M and X4 M, as well as the Alpina B3 and B4. It has four valves per cylinder, so 24 springs.
From the factory, BMW uses two spring part numbers, 11 34 7 523 971 and 11 34 8 603 911, twelve of each. The inlet valves have a 5 mm stem and the exhaust valves a 6 mm stem, with collets 11 34 1 438 142 and 11 34 1 461 405.
FERREA reinforced valve spring kits
Closing the valve and keeping it on the cam is the spring's whole job. The faster the engine turns, the more energy the valve carries; too little load lets it lift off, bounce or even hit the piston.
KT4059 quotes 400 N seat pressure at 37.0 mm, with titanium retainers 40% lighter than steel according to FERREA.
Valve spring kit technical specification
| Part number | Brand | Springs | Outer / inner Ø | Seat pressure | Open pressure | Rate | Max lift | Kit contents |
|---|---|---|---|---|---|---|---|---|
| KT4059 | FERREA | Single | Outer 23.4 / 16.8 mm | 400 N at 37.0 mm | 35.2 N/mm | 11.0 mm | 24 springs, 24 titanium retainers, 24 spring seats, 24 stem seals with integrated seat | |
| KT4061 | FERREA | Conical | 24 springs, 24 titanium retainers, 24 spring seats, collets (12 K10122, 12 K10123) |
Valve spring kit fitting details
| Part | BMW original | Reinforced spring kit |
|---|---|---|
| Spring | 11 34 7 523 971 / 11 34 8 603 911 (12 of each) | Kit specific: S10186 single (KT4059) or S2035 conical (KT4061) |
| Retainer | Kit specific, titanium: E11153 / E11154 (KT4059) or E12052 / E12053 (KT4061) | |
| Spring seat | Kit specific: SL1191 and SL1189 / SL1190 (KT4059) or SL1193 (KT4061) | |
| Collets | 11 34 1 438 142 (Ø 5 mm) / 11 34 1 461 405 (Ø 6 mm) | Original kept (KT4059) or K10122 / K10123 (KT4061) |
KT4059 includes 24 S10186 single springs, 24 titanium retainers (12 E11154 inlet, 12 E11153 exhaust), 24 SL1191 spring seats and 24 stem seals with integrated seat (SL1190 inlet, SL1189 exhaust). KT4061, from the PRO range, brings 24 S2035 conical springs, 24 smaller E12053 and E12052 titanium retainers, 24 SL1193 spring seats and its own K10122 and K10123 collets.
With the valve closed, installed height is the dimension between the lower and upper retainers. The quoted seat pressure is only correct at that exact height. After seat recutting the height grows and every additional millimetre costs as many newtons as the spring's rate figure. Measure each valve individually before assembling the new kit.
| FERREA | |
|---|---|
| Installed height | KT4059 : 37.0 mm |
| Seat pressure at this height | 400 N |
Technical guide
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Founded in Florida in 1978, FERREA Racing Components bears the name of Horacio Ferrea, an Argentine engine builder who teamed up with Daniel Urrutia. It makes valves, springs and valvetrain parts in its own workshops, used in NASCAR, on drag strips and on race circuits. |
How to choose
More pressure holds the valve against its cam lobe at high rpm: it lets you use a sharper camshaft, more boost or a higher limiter without valve float. Your cam lift has to remain under the kit's max lift, 11.0 mm for KT4059; beyond it, the coils touch before full opening.
| Criterion | Key point |
|---|---|
| Choosing the pressure | The S10186 spring of KT4059 gives 400 N seat pressure at 37.0 mm, with a rate of 35.2 N/mm. The right level depends on cam lift, target rpm and boost pressure, which climbs quickly on this twin-turbo once remapped. Stay close to the actual need: an overly stiff spring only wears cams and rocker fingers, for no extra power at all. KT4061 from the PRO range changes layout with its conical spring, smaller retainers and its own collets. |
| Single or conical spring | Single (KT4059): one cylindrical spring per valve, as from the factory, with titanium retainers and new stem seals. Conical (KT4061): a spring narrower at the top, paired with a smaller-diameter retainer, which reduces moving mass. |
When reinforced springs become necessary
- Camshafts with higher lift than stock
- Rev cut raised by remapping
- More boost pressure on this twin-turbo
- Head prepared for circuit, drift or rally use
- Tired stock springs, valves floating near the redline
Compatible vehicles
| Model | Engine code | Power | Years |
|---|---|---|---|
| Alpina B3 (G20) Biturbo | S58B30A | 2019-2025 | |
| Alpina B3 Touring (G21) Biturbo | S58B30A | 2019-2025 | |
| Alpina B4 Gran Coupé (G26) Biturbo | S58B30A | 2022-2025 | |
| BMW M2 (G87), M2 CS | S58B30A | 2022- | |
| BMW M3 (G80) Competition, M3 CS | S58B30A | 2020- | |
| BMW M3 Touring (G81) Competition | S58B30A | 2022- | |
| BMW M4 (G82) Competition, M4 CS, M4 CSL | S58B30A | 2020- | |
| BMW M4 Cabriolet (G83) Competition | S58B30A | 2021- | |
| BMW X3 M (F97), X3 M Competition | S58B30A | 2019- | |
| BMW X4 M (F98), X4 M Competition | S58B30A | 2019- |
OEM part numbers (valve springs): 11 34 7 523 971 and 11 34 8 603 911.
Related products
A head strip-down is the right moment to replace the inlet and exhaust valves as well, so they work with the firmer springs. Check the guides too.
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Brand
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ReferenceKT4059
