The Borg-Warner EFR6758 is the bigger brother to the 6258, allowing for more horsepower potential with minimal sacrifice in spool, featuring some of the latest and greatest technology. The team behind the EFR program are motorsports and engineering enthusiasts through and through and this product line existing for motorsport purposes is purely down to their skunkworks team and the drive to make the best product for all motorsport disciplines.
“The First Two Cars to Receive EFR Turbos Were the Author’s Porsche 911 and Fellow Employee Doug Erber’s Mazda Miata. Accelerating our Product Observations Through the Installation Process Was a Key Early Step in the Program, Leading to Mid-Stream Improvements. ”
You can read more about the development process and detail around the finished product here; efr_technical_training_book
Compressor Specifications
- Compressor Type: Forged-Milled Wheel (FMW) Extended Tip
- Compressor Wheel OD (exducer): 67mm
- Compressor Wheel Inducer: 53.9mm
- Max Flow Rate: 53 lb/min (530bhp potential)
- Built-in Recirculated BOV: Improve response on throttle transitions
- Compressor Housing: 2.5″ inlet, 2.0″ hose coupler outlet.
Turbine Specifications
- Turbine type: Low Inertia Gamma-Ti Turbine Wheel
- Turbine Wheel OD: 58mm
- Stainless Steel Investment Cast Housing
- 0.64 A/R T25 Housing (Internal WG)
- 0.80 A/R T4 Twin Scroll Housing (Internal WG)
- Turbine outlet: GT-Vband (aka small 3″ vband) ~92mm OD for all EFR turbos
Features
- Dual Row Ceramic Ball Bearings – lowest friction and fastest spool/response, most extreme durability, built-in oil control orifice – (aka oil restrictor)
- Watercooled Center Section – water cooling is recommended, 14mm banjo bolts
- Double seals on both turbine and compressor end for extreme durability and resistance to any oil seepage
- Boost Control Solenoid Valve Integrated to Compressor Housing
- Integrated Speed Sensor mounting provisions
- Capable of 4.0 Pressure Ratio or 43PSI of Boost
Compressor Map
BOFI Tuning Recommendations / Notes
On an optimised setup this turbo can be pushed as far as 32psi of boost pressure on a built 1.8 BP engine, theoretically making around 480-500bhp at the absolute limit. A reasonable power goal for this setup would be 420-440bhp with the 6258 sitting around 400-420.
On E85 this turbo has achieved over 490bhp on a dynojet chassis dyno.
See our BorgWarner EFR Equipped Car here!