The Differences Between Your Race Car and Daily Driver Torque Converter

The Differences Between Your Race Car and Daily Driver Torque Converter

Comparing the torque converter in your daily driver (or tow vehicle) to the one in your drag race car is like comparing the kid that grows up to be an office manager to his or her sibling that pursued a career in the US Marine Corps.  While they both come from the same beginnings, one took a much different path and was molded to a specific, heavy duty purpose. 

And if your daily driver is your race car, or you don't drive an automatic, or you don't even have a race car, here's a video of Australian burnout competitions. 

Torque converters for passenger vehicle designs have evolved over the decades with large improvements in:

  • Fuel economy
  • Lock up clutch life and smoothness of operation
  • General durability and reliability (well, mostly)

Drag racing converters are designed and modified to:

  • Remain reliable under increasingly demanding conditions 
    • Rapid development in turbo, supercharged, and nitrous powerplants
    • Extreme automatic transmission fluid temperatures as a result of staging requirements in these setups, turbos particularly
  • Work in unison with the engine and suspension to transfer power through the drivetrain and to the ground without losing traction
  • Work in unison with the engine, gearing, camshaft, tire diameter, and other factors to keep the car in its best average horsepower RPM range

The differences in these mission requirements are highlighted in the methods of manufacturing and modification.  Here are the two major examples.

Torque converter front (or cover)

In an OEM converter, the front is typically constructed of stamped steel, and in modern vehicles will contain some variant of a lock up clutch.  The light stamped steel cover and lock up clutch aid the car in lowering fuel consumption.  The pads that secure the converter to the flexplate are simply welded to the stamped cover and feature a mild-mannered 3/8" bolt.

In comparison, the forged steel cover as featured in our 8, 9, and 10-inch race converters is machined from a single forged steel piece.  The bolt holes are increased to 7/16" (and available at 1/2" in some cases).  In this case, the lockup isn't even part of the assembly, as this converter is designed for a non-lockup transmission.  (Though lock-ups do exist for many typically non-lockup transmissions)

Stator assembly

The stator of this OEM converter is designed for a specific car, with a specific engine, drive train, and gearing option to provide a very exact performance profile. This one, like many others for daily driven vehicles, actually contains some components that are plasticlike or composite. Such materials would be unsuitable and likely melted or destroyed in a heavy duty race application. (The OEM sprags and stators are often the first components to fail when adding additional power).

plastic, HAHA

Our racing stator is made from 8620 steel and finished machined on a CNC mill to accept a heavy duty sprag, diode, or spragless insert.  Steel and special alloy aluminum stators give the converter designer many options to adjust the stall, torque multiplication, and efficiency of operation.  

As we often write, all torque converters have a shared origin, even the fancy all-billet race converter designs from from the OEM versions. Modifiying or building a drag racing converter addresses the specific requirements of the racer, and should be noted when deciding on a full race converter vs. a "street/strip" version.

Posted by Brandon Barrentine at 2:39 PM