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S55 Common Modifications

Recommended hardware upgrades for the BMW S55 platform. These modifications support increased power levels and improve reliability for street and track use.

Always research thoroughly before purchasing modifications. Quality varies significantly between brands. When in doubt, consult with experienced tuners or the community.

Upgraded Intakes

The S55 responds well to intake upgrades that improve airflow to the twin turbochargers. Quality intakes reduce restriction and heat soak while increasing induction sound.

Recommendations:

  • -Eventuri Carbon Intake
  • -aFe Momentum Intake
  • -Dinan High Flow Intake
  • -BMS Performance Intake

The S55 benefits from intakes that feed both turbochargers evenly. Carbon fiber intakes offer the best heat resistance.

Upgraded Intercoolers

The stock S55 intercooler is larger than the N55 unit but still becomes a bottleneck when tuned. Upgraded intercoolers significantly reduce intake air temperatures.

Recommendations:

  • -Wagner Tuning Competition Intercooler
  • -CSF High-Performance Intercooler
  • -VRSF Race Intercooler
  • -Bar and plate construction preferred

The S55 generates significant heat with twin turbos. A quality intercooler is essential for consistent power on track.

Upgraded Charge Pipes

The S55 uses more robust charge pipes than the N55, but upgraded aluminium pipes still offer benefits for reliability and flow at higher boost levels.

Recommendations:

  • -Aluminium charge pipe kit
  • -Upgraded silicone couplers
  • -VRSF, BMS, or Mishimoto kits
  • -Upgraded throttle body inlet pipe (J Pipe)

While less failure-prone than N55 pipes, upgraded charge pipes ensure reliability at high boost levels.

Downpipes & Exhaust

The S55 has two downpipes (one per turbo). Upgraded downpipes significantly reduce backpressure and improve turbo spool, unlocking substantial power gains.

Recommendations:

  • -Catless downpipes for maximum flow (off-road use)
  • -High-flow catted downpipes for emissions compliance
  • -VRSF, ARM, or Evolution Racewerks downpipes
  • -Equal length design recommended

Both downpipes should be upgraded together. A tune is required to prevent CEL codes with catless downpipes.

Turbo Upgrades

The stock S55 turbos can support significant power with supporting mods. For beyond stock turbo limits, hybrid or full turbo upgrades are available.

Recommendations:

  • -Stock turbos can support significant power with supporting mods
  • -Hybrid turbos: Pure Turbos Stage 2, Vargas Turbo
  • -Full turbo upgrades for extreme builds
  • -Upgraded wastegate actuators recommended

The twin turbo configuration makes turbo upgrades more complex and expensive than single turbo setups.

Oil Catch Can

Like the N55, the S55 is prone to carbon buildup on intake valves. Catch cans help prevent oil vapors from contaminating the intake.

Recommendations:

  • -Baffled catch can with drain valve
  • -Mishimoto, JLT, or Burger Motorsports catch cans
  • -Regular emptying required

Essential for maintaining intake cleanliness. Track use increases oil vapor production.

Spark Plugs

Proper spark plug selection and gapping is critical for tuned applications to prevent misfires.

Recommendations:

  • -Stock spark plugs: NGK 97506
  • -Gap to ~0.022 inches for tuned applications
  • -Consider upgraded coil packs as an alternative to smaller gaps

Running smaller gaps reduces spark plug service life but helps prevent misfires under boost.

Fuel System Upgrades

Fuel system upgrades are essential for higher power builds and ethanol (E85) applications.

Low Pressure Fuel Pump (LPFP)

The S55 LPFP can support more power than the N55 unit. Stock LPFP is adequate for stock turbo E85 applications.

Recommendations:

  • -Stock S55 LPFP is adequate for stock turbo applications including E85
  • -Walbro 450/460 LPH fuel pump for E85
  • -Walbro 525 LPH for high power E85 applications
  • -BMP or Fuel-It! LPFP upgrade kits

High Pressure Fuel Pump (HPFP)

The S55 HPFP flows more than the N55 unit. Stock HPFP handles E85 fine but struggles beyond stock turbo power levels.

Recommendations:

  • -Stock S55 HPFP is adequate for stock turbo applications including E85
  • -Spool Performance FX-Series HPFP for upgraded turbo builds
  • -Dorch HPFP upgrades
  • -Upgraded HPFP recommended for beyond stock turbo power

Fuel Injectors

The S55 uses larger injectors than the N55. Stock injectors handle E85 fine on stock turbos but need upgrades beyond that.

Recommendations:

  • -Stock S55 injectors are adequate for stock turbo applications including E85
  • -Upgraded injectors required for beyond stock turbo E85 builds
  • -Port injection is an option for extreme builds
HPFP & LPFP Flow DataInjector Flow Data