BNR S4V4 Turbocharger Upgrade

The BNR S4 version 4 turbocharger has a 3.5” inlet and works with a 3.5” or larger intake pipe.   All the tuners like using an aftermarket boost control solenoid with a single barbed wastegate actuator.  The S4’s point milled billet compressor wheel is rated for 53 lb/min air flow and is the smallest of the 71mm Garrett compressor wheels. The BNR S4 is the most popular turbocharger in the MZR market!  The S4 will max out the original engine and has enough on the table to make mid 500  WHP with Auxiliary fueling in internal wastegated orientation.   Great response and amazing sounds come from this unit!  Makes a great entry level turbocharger for built engines.

• BNR G30-770 CHRA Rated at 66 lb/min
• VSR Balanced
• BNR Upgraded compressor housing with Antisurge port
• Heavy Duty 15 psi wastegate actuator
• Heavy Duty wastegate swing valve construction
• 30 mm wastegate port
• .72 a/r turbine housing

Install kit includes:

• • 9 M10 1.5 stainless studs
  • 9 M10 1.5 stainless nuts
  • 9 M10 stainless washers
  • 2 M12 copper sealing washers
  • 4 M14 copper sealing washers
  • 2 Oil outlet gaskets
  • Stainless MLS turbine inlet gasket
  • Stainless MLS turbine outlet gasket
  • Firewall side extended stainless water line

BNR Supercars specializes in the Mazdaspeed3 and Mazdaspeed6 turbochargers. 

Peak numbers are not what we are into.  We like designing turbocharger upgrades that produce maximum under the curve power and torque.  It makes these cars much more responsive and fun to drive on the street.  When you get greedy and go for that peak number, it kills the bottom and mid-range torque.   No bottom end torque makes the engine not as responsive for autocross/road racing and in BNR's opinion not as fun to drive!

These engines are doing very well handling 400-450 WHP with the stock bottom end.  Most people looking for a reliable replacement over the stock smoking KO4 usually go for the S1 or S2 turbocharger models since a tune isn’t required.  If your car is fully bolted with high performance fuel pump internals we suggest an S3 with a tune.  Fully bolted with added methanol injection go with the S4 and a tune.   Stock engine internals, don’t even think about doing an S5 or S6!

*Divorced down pipes do not work with BNR turbocharger upgrades!  If they are used, the wastegate valves will not open properly causing extreme high boost problems!*

*Built engines need a custom oil supply line for turbocharger protection! 

*S5 and S6 model turbochargers to cover the cost of the custom oil drain line! 

*Please note, turbos may ship directly from BNR, so please allow extra time for the turbo to be built and delivered.