BorgWarner Turbo Rebuild

K03

The most common KKK turbo in the VW/Audi ecosystem. OEM on the 1.8T engine in multiple configurations across Audi A4, A6, VW Passat, and Golf. Part numbers typically begin 5303-970-XXXX (complete) or 5303-988-XXXX (CHRA). Water-cooled journal bearing. The K03 is frequently brought in worn from extended oil intervals or contaminated oil on high-mileage 1.8T engines.

K04

The K04 is a step up from the K03 in the same family. OEM on the Audi TT 225HP, S3, and Golf R32. Also the most common VW/Audi 1.8T upgrade path, since many K03-equipped platforms use the K04 as a direct upgrade. Part numbers 5304-XXXX. Same water-cooled journal bearing design. The K04-015 (53049700015) is one of the most-rebuilt KKK units we see.

K14 / K16

K14 is used on smaller European diesel applications including VW Polo 1.4 TDI and related platforms. K16 covers a range of European diesel OEM applications across the Volkswagen Group and other European makes. Both are journal bearing units. Common failure is sludge from extended diesel oil intervals which restricts the small oil passages in the compact CHRA.

K24

The K24 was OEM on the Porsche 944 Turbo and 944 Turbo S, and has been used in various marine and industrial applications. Larger than the K03/K04 family. Journal bearing. The Porsche 944 Turbo K24 is a frequent rebuild unit given the age of these vehicles: coking and oil contamination from decades of service are the typical findings at teardown.

K26

The K26 covers a wide range of configurations across automotive, marine, and industrial applications. Porsche 911 Turbo (930 series), various MAN bus applications, Mercruiser and Yanmar marine engines. Multiple compressor and turbine wheel combinations within the K26 frame. Contact us with your specific part number (5326-XXX-XXXX) to confirm the configuration for your rebuild.

K27

The K27 is a heavy-duty commercial diesel unit used across Deutz, Cummins, and various truck platforms. The K27-3072 configuration covers 250-550 HP and is listed in the BorgWarner AirWerks catalog. The K27 has also served as a Holset HX35W replacement in some Cummins applications. Journal bearing. Used extensively in European commercial truck and bus platforms.

K28 / K29 / K31

K28 covers performance and larger diesel applications. K31 is the large-frame unit used on the Detroit Diesel 12.7L Series 60 in truck and bus applications; the K31 uses a Forged Milled Compressor Wheel (billet) as standard. K29 covers Caterpillar and various commercial applications. All journal bearing units in the traditional KKK architecture.

KP31 / KP35 / KP39 / BV39

The KP-series and BV39 are variable geometry (VNT) turbos used extensively across VW, Audi, Seat, Skoda, and Mercedes diesel platforms. KP31 for small engines, KP35 for medium, KP39 and BV39 for the popular 2.1D Mercedes Sprinter and various TDI applications. The variable nozzle vane system requires the same VGT service attention as Holset VGT units: vane carbon buildup is the dominant failure mode. Part numbers begin 5431, 5435, 5439.

K33 / K34 / K36 / K37 / K42 / K44

Larger KKK frames used in industrial, agricultural, and commercial applications. K33 and K34 cover mid-range industrial engines. K36 and K37 are used in heavier commercial applications. K42 and K44 cover large industrial and marine diesel applications. Contact us with your nameplate part number (format 53XX-970-XXXX) and we will confirm what the rebuild involves.

The Schwitzer S-series is the dominant performance diesel turbocharger family in North America. All S-series turbos use twin hydrodynamic journal bearings and adjustable housing orientation (both compressor and turbine housings can be repositioned independently). The aftermarket shorthand "S366" or "S480" indicates the frame size (S300 or S400) and the compressor wheel inducer diameter in mm. Full BorgWarner nomenclature includes turbine wheel size and A/R (e.g., S300SX3 66/80 .91).

S300 / SX3

The S300SX3 (cast wheel) is the workhorse of the AirWerks lineup. Available in S360 (60mm), S362 (62mm), S363 (63mm), S364 (64mm), S366 (66mm), and S369 (69mm) compressor wheel configurations. T3 and T4 turbine housing options. The S366 is the single most popular diesel performance turbo in North America, capable of 500+ RWHP in the right application and widely used as both a single and the high-pressure charger in compound setups over an S400.

S300 SX-E

The SX-E (Super eXtended) line upgrades the S300SX3 with a Forged Milled Compressor Wheel (FMW), 360-degree thrust bearing, integrated speed sensor port, and extended tip technology. Same frame and housing options as SX3 but significantly improved efficiency and airflow capacity. The S300SX-E is BorgWarner's current production performance line for the S300 frame and the preferred choice for serious street and track diesel builds.

S400 / SX3

The S400 frame is BorgWarner's large-frame diesel performance unit. T4 and T6 turbine housing options. Common configurations include S464 (64mm), S467 (67mm), S472 (72mm), S476 (76mm), and S480 (80mm). The S467.7 is one of the most popular large-frame units for Cummins and Powerstroke builds supporting 600-800 RWHP. S400 units are frequently used as the low-pressure (atmospheric) charger in compound S300/S400 setups.

S400 SX-E

The S400SX-E applies the same FMW, 360-degree thrust bearing, and extended tip technology to the large S400 frame. T6 turbine housings are available for maximum exhaust flow on very high HP applications. The S488 SX-E (88mm compressor) is capable of supporting over 1,200 HP in extreme applications. Large-frame SX-E units are the choice for top-tier competition diesel builds.

S200 / S1 / S100

The smaller Schwitzer frames used on OEM diesel applications in commercial and agricultural settings. S100 and S200 appear on Deutz, Volvo Penta, and various light-duty diesel platforms. While less common than S300/S400 in the performance market, these units are regularly rebuilt for commercial applications. Contact us with your specific part number and we will confirm rebuild availability.

Every EFR turbocharger uses a dual ceramic ball bearing assembly with metal cage, a Gamma-Ti (titanium aluminide) turbine wheel, an integrated compressor recirculation valve (CRV), a boost control solenoid valve (BCSV), and a Forged Milled Compressor Wheel (FMW). The Gamma-Ti turbine wheel is lighter and more heat-resistant than conventional Inconel, enabling higher shaft speeds and faster response than ball bearing turbos using conventional materials. However titanium aluminide is brittle when cold: this is the most common EFR failure we see. The wheel must be fully up to operating temperature before any boost demand. Cold hard revs on an EFR are the fastest way to crack the turbine wheel. All EFR units are VSR balanced in-house at rebuild, and the ceramic ball bearing cartridge is matched to the rebuilt assembly.

EFR6258

The smallest and fastest-spooling EFR unit. 62mm compressor / 58mm turbine. The EFR6258 is the go-to upgrade for 4-cylinder applications where response is the priority: Mazda MX-5, Honda K-series, Subaru EJ, and smaller displacement builds. Part numbers 179140 (supercore) and 179150 (with 0.64 A/R housing). Integrated CRV and BCSV are standard on all EFR units.

EFR6758

67mm compressor / 58mm turbine. Steps up from the 6258 in flow capacity while retaining the small turbine for fast response. Popular on 2.0L-2.5L 4-cylinder builds and smaller 6-cylinder applications where 300-550 HP is the target range. A balance of response and peak power that suits most aggressive street builds on 4-cylinder platforms.

EFR7163

71mm compressor / 63mm turbine. One of the most popular EFR units for medium-frame 4-cylinder and small 6-cylinder applications. Capable of 400-650 HP depending on application. The 7163 is frequently used on 2.0L-3.0L 6-cylinder builds where the 6758 has been outgrown. Available in multiple A/R turbine housing configurations. Part number reference: 11711013004 (compressor cover).

EFR7670

76mm compressor / 70mm turbine. Steps into the mid-large frame range. Used on 2.5L-4.0L engines targeting 500-750 HP. Suitable for single-turbo 2JZ builds that have outgrown the factory twin setup, larger 4G63 builds, and RB26 upgrades. The 7670 is where the EFR line transitions from 4-cylinder-focused to genuinely capable on 6-cylinder platforms. Part number reference: 12761013034.

EFR8374

83mm compressor / 74mm turbine. One of the largest practical single-turbo EFR units for gasoline performance applications. 500-900 HP capable. Popular for large-displacement single-turbo builds on 3.0L-5.0L engines. The 8374 pushes the limits of what can be achieved with a gasoline-fueled single turbocharger while maintaining ball bearing response characteristics. Part number reference: 12831013012.

EFR9174 / EFR9180

The largest EFR units. 91mm compressor with 74mm (9174) or 80mm (9180) turbine. 700-1100 HP capable on gasoline. The EFR9174 and EFR9180 are serious race units: at this size the ball bearing advantage in spool time is most apparent versus comparably-sized journal bearing turbos. Contact us before shipping, since large-frame EFR rebuilds are assessed individually based on configuration and ball bearing cartridge condition. Part numbers shared: 12911013005.