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BMW 118i F20/F21 136hp B38B15A 2015-2019
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BMW 118i F20/F21 136hp B38B15A 2015-2019
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Kit of 12 reinforced valve springs for the BMW and MINI B38.
This kit fits the BMW B38 three-cylinder turbo engine, 1.2 and 1.5 litre with 12 valves, used in the BMW 1, 2, 3 and 4 Series, X1, X2 and i8 as well as in the MINI F54, F55, F56, F57, F60 and their successors, since 2013.
The valves, with a 5 mm stem on the inlet side, are operated by roller finger followers with a hydraulic element and closed by single springs: 11 34 7 618 835 or 11 34 8 623 323 on the inlet, 11 34 8 603 911 on the exhaust. They are held by the retainers 11 34 7 539 917 (inlet) and 11 34 7 614 134 (exhaust) and by the collets 11 34 1 438 142 and 11 34 1 461 405.
The cam pushes the valve open; the spring is what sends it back onto its seat and forces it to follow the cam profile right to the end. As the engine picks up revs, the valve and its retainer build up momentum: a spring that is too soft then lets them fly, the valve bounces and may touch the piston. This is called valve float, and it puts a ceiling on any gain in revs or lift.
The SUPERTECH kit keeps one spring per valve, as originally fitted, and publishes its behaviour precisely: 334 N seat pressure at a height of 37.0 mm, 689 N once the valve is lifted by 10 mm, with a rate of 35.6 N/mm and coil bind reached at a height of 23.2 mm. Each spring comes with its own dedicated retainer, RET-BMB48-TI on the inlet side and RET-BMB48-TE on the exhaust side, for a complete rebuild with nothing else to buy.
| Part number | Brand | Springs | Outer / inner Ø | Seat pressure | Open pressure | Rate | Max lift | Kit contents |
|---|---|---|---|---|---|---|---|---|
| SPRK-MCB38 | SUPERTECH | Single | 334 N at 37.0 mm | 689 N at 10 mm | 35.6 N/mm | 12 springs, 12 retainers |
| Part | BMW original | Reinforced spring kit |
|---|---|---|
| Spring | Single: inlet 11 34 7 618 835 or 11 34 8 623 323; exhaust 11 34 8 603 911 | Kit specific |
| Retainer | Inlet 11 34 7 539 917; exhaust 11 34 7 614 134 | Kit specific |
| Spring seat | Original kept | |
| Collets | Inlet 11 34 1 438 142; exhaust 11 34 1 461 405 | Original kept |
SUPERTECH SPRK-MCB38: 12 SPR-FE20BE springs, 6 RET-BMB48-TI retainers (inlet) and 6 RET-BMB48-TE retainers (exhaust) supplied.
The installed height is the gap between the spring seat and the retainer when the valve is closed. The SUPERTECH seat pressure applies to 37.0 mm; a greater height, after recutting the valve seats for example, loses for every millimetre the equivalent of the spring rate shown in the specification table.
| SUPERTECH | |
|---|---|
| Installed height | 37.0 mm |
| Seat pressure at this height | 334 N |
 | From San Jose, California, SUPERTECH has been working on competition valvetrains for some thirty years and more. Its springs are wound from high purity chrome-silicon-vanadium wire, its retainers cut from titanium reserved for military use, and its production is checked by ultrasound, X-ray and laser. |
Reinforced springs delay the moment when the valve leaves the cam: that is what makes a remap with more boost, a raised rev limit or reworked camshafts possible without valve float. This kit delivers 334 N seat pressure and 689 N at 10 mm lift. The point to watch: the lift of the new camshaft, to be compared with the coil bind height stated by SUPERTECH, 23.2 mm.
| Criterion | Key point |
|---|---|
| Choosing the load | The 75 lbs quoted by SUPERTECH is the force on the seat expressed in pounds, i.e. 334 N, and the 155 lbs the load once the valve is open by 10 mm, i.e. 689 N. The right load follows from your cam lift, the maximum revs you are after and the boost level: as these rise, the spring has to get firmer. No excess though, as a spring stiffer than needed wears the cams and puts more strain on the finger followers and their hydraulic elements, which end up collapsing. Better to start from the load published by the manufacturer and only exceed it if the camshaft demands it. |
| Single or double spring | The kit keeps a single spring per valve, like the original B38 layout. We do not offer a double spring version for this engine. |
| Model | Engine code | Power | Years |
|---|---|---|---|
| 116i / 118i (F20 / F21) | B38 | 2015-2019 | |
| 116i / 118i (F40) | B38 | 2019- | |
| 118i (F52) | B38 | 2017-2019 | |
| 116 / 118 / 120 Mild-Hybrid (F70) | B38 | 2024- | |
| 216i / 218i / 225xe (F45) | B38 | 2014-2021 | |
| 216i / 218i / 220i / 225e / 230e (U06) | B38 | 2021- | |
| 218i / 220i (F22 / F23) | B38 | 2015-2021 | |
| 216i / 218i (F44) | B38 | 2019- | |
| 216 / 218 / 220 (F74) | B38 | 2024- | |
| 216i / 218i Gran Tourer (F46) | B38 | 2015- | |
| 318i (F30 / F31) | B38 | 2015-2019 | |
| 418i (F32 / F36) | B38 | 2015-2020 | |
| X1 sDrive18i / xDrive25e (F48) | B38 | 2015-2022 | |
| X1 sDrive16i / 18i / 20i / xDrive25e / 30e (U11) | B38 | 2022- | |
| X2 sDrive18i / xDrive25e (F39) | B38 | 2018-2023 | |
| X2 sDrive16i / 18i / 20i (U10) | B38 | 2023- | |
| i8 (I12 / I15) | B38 | 2014-2020 | |
| MINI Cooper / One (F55 / F56 / F57) | B38 | 2013- | |
| MINI Cooper C / One (F65 / F66) | B38 | 2024- | |
| MINI Clubman Cooper / One (F54) | B38 | 2015-2024 | |
| MINI Countryman Cooper / ALL4 / SE / One (F60) | B38 | 2016- | |
| MINI Countryman C (U25) | B38 | 2023- |
OEM part number (valve spring): inlet 11 34 7 618 835 or 11 34 8 623 323; exhaust 11 34 8 603 911
A head stripped to change the springs also deserves new inlet and exhaust valves, especially on a high mileage engine. Our valves for the B38:
| BMW B38A15 B38B15 inlet valves → |
| BMW B38B15 exhaust valves → |
