DOC Race Top-Mount Single Precision Turbo Kit – BMW 335i / 135i (N54)

OVERVIEW

The DOC Race top mount single turbo kit is built for the N54 street machine that needs to make serious power without giving up drivability. DOC Race currently holds the N54 single turbo horsepower record at 889 hp with this platform, and the kit ships complete with the hardware needed to install it. Precision Turbo (PTE) units are used throughout because they combine top-tier performance with the durability to run for years without service.

The heart of the kit is the DOC Race T4 twin-scroll manifold. Redesigned in September 2020 as a one-piece unit for easier installation, it was proven on a handful of very high-output race cars before it was ever fitted to the DOC Race test car, and it is capable of supporting well beyond 1000 hp. Boost is regulated by a pair of Turbosmart 40mm wastegates mounted low and away from exhaust heat, so wastegate springs can be swapped on the dyno or after hard runs without pulling hot exhaust components.

Charge air is fed to the intercooler through a single 2.5" aluminum charge pipe, and the two-piece 3" stainless downpipe is V-band joined and connects to the factory exhaust or any aftermarket exhaust that accepts factory gaskets.

SPECS

• Holds the N54 single turbo horsepower record at 889 hp (DOC Race)
• One-piece DOC Race stainless T4 twin-scroll V-band manifold, redesigned 9/2020
• Manifold capable of supporting well beyond 1000 hp
• Two Turbosmart Comp40 40mm external wastegates supplied with 14 psi springs
• Wastegates mounted low, away from exhaust heat, for easy spring access
• Single 2.5" aluminum intercooler charge pipe
• 3" stainless steel two-piece V-band downpipe, connects to factory-location exhaust
• Turbo options and DOC Race power ratings: 5862 GEN2 CEA – 640 hp; 6062 GEN2 CEA – 750 hp; 6266 GEN2 CEA – 800 hp; 6466 GEN2 CEA – 900 hp; 6766 CEA – 935 hp; 6870 GEN2 CEA – 1100 hp
• Fits rear-wheel-drive models only
• Lead time: 6–8 weeks from order

PARTS INCLUDED

• Precision (PTE) turbocharger
• 2 x Turbosmart Comp40 wastegates with 14 psi springs
• DOC Race stainless multi-piece V-band manifold
• 3" stainless upper downpipe
• 3" lower downpipe (connects to factory location exhaust)
• V-band clamps
• 2 x stainless dump tubes
• 2.5" aluminum intercooler charge pipe
• 2.5" silicone couplers and clamps
• 4" shorty filter
• 5/8" oil drain line hose
• Heat shield
• T4 turbo gasket
• 6 x OEM style doughnut gaskets
• 4 x 10x1.25 studs and nuts
• -4AN oil feed line kit
• Coolant block-offs and oil feed adapter fitting
• CNC coolant pipe and hardware
• Coolant tank relocation bracket
• Coolant hose to water pump with hose clamps
• 5/8" silicone hose to coolant tank, 5/8" barb fittings and hose clamps
• Assorted nuts and bolts
• 10 ft silicone vacuum hose and 3 x vacuum tees
• DOC Race turbo blanket

TECH RESOURCES

Additional Parts Required

• Engine management / tuning. The kit must be tuned by an established N54 tuner. Options we stock include the JB4 Tuner for N54 BMW; MHD flash tuning is also commonly used on this platform.
• Upgraded fueling above 550 hp. Factory injectors support roughly 550 hp. DOC Race advises adding an aftermarket port injection system beyond that level and runs an AD-Engineering port injection kit with additional injectors on the DOC Race car, driven daily without stalling.
• Upgraded intercooler is recommended if one is not already fitted — for example the CSF High-Performance N54 Intercooler.
• Supporting hardware for your power target — charge pipe / BOV combination, clutch, and fresh brakes, tires and any deferred maintenance.
• Preventative maintenance parts DOC Race suggests replacing during the install: 2 x BMW OEM 2-bolt exhaust gaskets (18307553603) and 1 x BMW coolant pipe O-ring (11537545302).
• A MAC solenoid is not included and is not required to install the kit. It is only needed if you want to change boost settings from a tuning device such as a JB4 or Motiv boost box.

Installation

• Subframe removal is not required. With the one-piece manifold the engine is lifted approximately 2" and the manifold is installed from above.
• The kit ships as two packages.
• DOC Race does not publish a downloadable installation manual for this kit. Contact Speed Logic at (888)-564-4215 for fitment and installation support.

Notes

• Call Us For More Information At (888)-564-4215!!!
• Please be aware if you place an order for a turbo kit today it will not ship for 6-8 weeks.
• This kit fits RWD models only. Please email us for AWD pricing.
• DOC Race does not publish an official part number for this kit, so no part number is listed. Model-year coverage is not stated by the manufacturer — confirm your exact year, drivetrain and transmission with Speed Logic before ordering. xDrive/AWD cars are not covered; email us for AWD pricing.

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