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N55 Common Modifications

Recommended hardware upgrades for the BMW N55 platform. These modifications support increased power levels and improve reliability.

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

Upgraded Intakes

Upgraded intakes allow more airflow to the turbocharger, reduce heat soak, and increase induction sound. The N55 benefits from quality intake upgrades, especially at higher power levels.

Recommendations:

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

Quality construction matters. Look for intakes with proper MAF housing and heat shielding.

Upgraded Intercoolers

The stock intercooler is adequate for stock power but quickly becomes a bottleneck when tuned. Upgraded intercoolers significantly reduce intake air temperatures for more consistent power.

Recommendations:

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

Larger intercoolers provide better heat dissipation. Consider your climate and power goals when sizing.

Upgraded Charge Pipes

The stock charge pipes are plastic and prone to cracking under increased boost pressure. Aluminium charge pipes are essential for any tuned N55.

Recommendations:

  • -Aluminium hot side and cold side charge pipes
  • -Upgraded silicone couplers with quality clamps
  • -VRSF, BMS, or Mishimoto charge pipe kits

This is a critical reliability upgrade. Stock charge pipes can fail suddenly, causing boost leaks and potential damage.

Downpipe & Exhaust

The factory downpipe is restrictive. Upgraded downpipes reduce backpressure, improve turbo spool, and unlock additional power especially when combined with a tune.

Recommendations:

  • -Catless downpipe for maximum flow (off-road use)
  • -High-flow catted downpipe for emissions compliance
  • -VRSF, ARM, or Evolution Racewerks downpipes
  • -3.5" diameter recommended for higher power applications

A tune is required to prevent CEL codes with catless downpipes. Consider full turbo-back exhaust for best results.

Upgraded Diverter Valve / BOV

The stock diverter valve handles stock boost levels but can struggle with increased boost. Upgraded valves ensure proper boost relief.

Recommendations:

  • -Upgraded piston-style diverter valves
  • -Turbosmart or Forge Motorsport DVs
  • -OEM N55 DV is more reliable than N54 but still benefits from upgrade

Essential for Stage 2+ applications. Prevents boost spikes and protects the turbo.

Oil Catch Can

Direct injection engines like the N55 are 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

Helps prevent carbon buildup. Without a catch can, periodic walnut blasting may be needed.

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. The stock fuel system can support approximately 450-500 HP on pump gas, but upgrades are needed beyond that.

Low Pressure Fuel Pump (LPFP)

The stock LPFP can support approximately 450-500 HP on pump gas. For ethanol blends beyond E50 or higher power levels, an upgraded LPFP is essential.

Recommendations:

  • -Walbro 450/460 LPH fuel pump
  • -Walbro 525 LPH for high power E85 applications
  • -BMP or Fuel-It! LPFP upgrade kits
  • -Upgraded fuel wiring harness recommended
  • -Stock LPFP supports up to E50 blend maximum

High Pressure Fuel Pump (HPFP)

The N55 HPFP is more robust than the N54 unit but still has limits. Upgraded HPFPs support higher fuel flow for increased power.

Recommendations:

  • -Spool Performance FX-Series HPFP
  • -Dorch HPFP upgrades
  • -Stock HPFP is limited - upgrade recommended for Stage 2+
  • -Upgraded HPFP essential for E85 at higher power

Fuel Injectors

Stock injectors are adequate for Stage 1-2 builds. Higher power applications require upgraded injectors to deliver sufficient fuel.

Recommendations:

  • -Stock injectors are adequate for most tuned applications
  • -Upgraded injectors required for heavy E85 use
  • -Port injection is an option for extreme builds
HPFP & LPFP Flow DataInjector Flow Data