GrimmSpeed Chase JB400 Turbocharger


GrimmSpeed SKU: GRM123005

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The GrimmSpeed Turbocharger Program started by recognizing a need in the market for a robust, quick-spooling and high-performing turbo. Design began from the ground up and took over 3 years of hard work, testing and development to introduce a product that we're proud to have carry The GrimmSpeed Name. The focus of this project was to offer a stock location OE replacement turbo, which when paired with GrimmSpeed supporting mods, allows enthusiasts to take full advantage of their EJ series turbo engine.

Both of our new turbocharger options feature state of the art proprietary compressors, turbines, CHRA's and wheel designs which maximize the power made on your EJ engine at two different price points. The overall design went through tedious gas flow test analysis, strenuous failure testing and engine pounding dyno/road testing, all to create the new standard for EJ engines: The GrimmSpeed Chase JB400 and Overtake BB500 Turbochargers!

The Chase JB400 Turbo is the smaller of our two offerings, this journal bearing unit is a perfect bolt-on to any stage 3 car, with which you are able to maximize the car’s power potential with instant results through installation/tuning. The Chase JB400 features a robust 49lb compressor wheel, with a 53mm turbine wheel to offer quick response and power in the mid-range where you need it. The Chase Version was able to hit 440WHP and 460WTQ on The GrimmSpeed Stage 3-equipped 2020 STI with the addition of only tuning and fuel mods. The impressive bit is that the vehicle was able to hold over 400WTQ from 4150RPM, an RPM range where the stock turbo begins to lose power. Compared to a tuned stock turbo STI, the Chase 400 is able to produce 70 more horsepower and 66 more ft/lbs of torque.


  • Compressor Wheel Size (Inducer/Exducer): 51.2mm / 73.8mm Extended tip, 48 Trim
  • Turbine Wheel Size (Inducer/Exducer): 53.8mm / 47mm, 76 Trim
  • Compressor Flow: 49 lb-min
  • Compressor Inlet Diameter: 2.4"
  • Compressor Wheel Type Material/Alloy: Billet 2618
  • Compressor Housing Alloy: A356
  • Turbine Housing Alloy: D5S
  • Bearing Type: Journal
    • Severe duty 360 degree thrust bearing and twin hydrodynamic bearings –very robust for this size of turbocharger, to ensure reliability at high boost levels and in race applications
    • Dual piston rings and advance oil flinger design to combat oil leakage and CHRA pressurization
  • Compressor A/R: 0.65
  • Turbine A/R: 0.88
  • Adjustable Wastegate: Pre-set at 15Psi base pressure


  • 2004-21 Subaru STI
  • 2002-07 Subaru WRX [Other modifications required]
  • 2004-08 Subaru Forester XT [Other modifications required]
  • 2008-14 Subaru WRX [Equipped with GrimmSpeed Intercooler, STI-Style Conversion Hose, etc]
  • 2005-09 Subaru Legacy GT [Equipped with GrimmSpeed Intercooler, STI-Style Conversion Hose, etc]
  • 2005-09 Subaru Outback XT [Equipped with GrimmSpeed Intercooler, STI-Style Conversion Hose, etc]