B&M 20485 Nitrous HoleShot 3800 Torque Converter, 1965-1991 GM TH400, TH425 TH375B, 1965-1981 GM TH350

10 in. diameter, 10.75 in. bolt circle, 3500-3800 RPM stall

PART# 20485

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NOTE: Stall speed listings are based on engines producing 230lb. ft. of torque at 2,500 rpm. More torque at 2,500 rpm will give you a higher stall speed, less torque at 2,500 rpm will give you a lower stall speed than the stall speed ratings than indicated in the description.


B&M Nitrous HoleShot 3800 stall for GM 1965-91 TH400, TH425, TH375 and 1968-81 TH350, TH375B (not TH350C.) The Nitrous Holeshot 3800 stall converter is an excellent choice for vehicles with engine modifications, particularly big cams that tend to reduce low end power and torque. The higher stall speed of this converter will launch the car in a higher rpm range where more torque is readily available, resulting in quicker acceleration. Nitrous Holeshot converters feature furnace brazed impeller and turbine, new precision steel alloy pump drive tube, new heavy duty needle bearings between the stator and impeller (not a thrust washer) and needle bearings between the stator and turbine.

Other features include a new turbine hub, new springs and rollers in the stator and anti-balloon plates. The anti-balloon plates will allow these converters to stand up to the instant horsepower that a Nitrous plate or fogger system delivers. These are serious converters for serious performance street cars. To prevent contamination left from worn parts being circulated in your new components causing premature wear, we strongly recommend protecting your investment by adding a B&M transmission cooler with all new transmission installations. Listed converters are NOT to be used in trans-brake applications. Not for use in trans-brake applications.


  • Fully Balanced and Pressure Tested
  • Dual pattern 10.75 and 11.50-inch bolt circle
  • Needle Bearing Between Stator and Turbine
  • Furnace Brazed Impeller and Turbine
  • Anti-balloon Plate for Added Strength
  • Steel Alloy Pump Drive Tube
  • Higher Stall Speed, Quicker Acceleration
  • B&M Quality & Durability

Product Attributes

Emission Code5
Product TypeTorque Converters
California Proposition 65 RequiredNo
Part Number20485



This part is legal for sale or use on Emissions Controlled Vehicles, Uncontrolled (Non-Emissions Controlled) Vehicles, and Racing Use Only Vehicles because it does not affect vehicle emissions and is not covered by emissions regulations.

Tech Resources

For vehicles with GM TH400, TH425, TH375 & TH350, TH375B (Not TH350C) Automatic Transmissions


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