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2005-2014 Torque Converters Explained

Written By: Glenn Cope II

An introductory guide to 2005-2014 S197 Mustang transmission torque converters on how they work, what they're used for and why you might want to upgrade yours.

Facts about a 2005-2014 Mustang’s Torque Converter

  • Torque converters are the link between an engine and the transmission
  • Stall speed is the rpm at which the converter achieves hydraulic lock
  • Torque converters in modern Mustangs are perfect for daily driving as well as performance driving
  • To maximize performance, it is best to match up the stall speed with the power curve of the motor

In the S-197 Mustangs there have been two automatic transmissions: 2005 through 2010 had the 5R55S five speed, and 2011 onward come with the 6R80 six speed unit. Both are electronically controlled transmission units with lockup torque converters. Like all S-197 Mustangs, the performance of the car with either transmission can be improved with a quality, high stall torque converter. Use the transmission tag identifier if your curious as to whether your Mustang has the stock transmission or not.

2006 GT and a 2014 GT ready for a run

What Does a Mustang's Torque Converter Do, and What About Stall Speed?  

Torque converters are the link between the Mustang's engine and the transmission. A torque converter's “stall speed” is the rpm at which the converter achieves a hydraulic lock, the point at which the car has to move or cause the engine to stall. Although generally a car will never reach that ultimate stall speed. The higher the stall speed the further into the power band the engine can reach without having to move. This allows the car to launch off the line with more power and rpm, greatly reducing elapsed times at the drag strip.

TCI Mustang Torque Converter

Is a Performance Torque Converter Okay for my Daily Driver?   

In short, the answer is yes. In the past, high stall torque converters were not the greatest thing to have in your daily driven street car. They would cause your Mustang to be in a constant state of slippage since the stall speed would be higher than the actual rpm needed to maintain the car's speed on the road. Because of the advent and wide spread usage of “lockup” type torque converters, this slippage is a thing of the past at cruising speed. A lockup torque converter has a large clutch plate inside that is applied by hydraulic pressure in the higher gears as directed by the powertrain control module, effectively locking up the torque converter and making for a solid connection between the motor and transmission. This means you can have your cake and eat it too. You get the high stall torque converter for those great launches at the drag strip as well as the lockup feature for the improved efficiency and mpg at cruise speed. We can all thank the fuel economy gods for this torque converter improvement.

2005-2012 Eleanor styled Mustang

Choosing a Torque Converter For Your Mustang 

Choosing the correct high stall torque converter for your Mustang makes a difference. In many instances there can be a half second or more drop in your quarter mile time. It would take a great deal of engine modifications to match the performance improvement that the high stall torque converter is capable of providing. Getting the correct stall speed to match the power curve of the motor is critical to maximizing performance. You want a converter that has a stall speed where the engine is getting to the meat of its power band. Somewhere in the area of 500 to 750 rpm below the torque peak for a max performance application is ideal. A street application can go for something more sedate if you rarely see the drag strip.  

Something else you must consider is that do make more heat, so it is a good idea to add a transmission oil cooler. This is a simple thing to do and there are many available kits that will more than compensate for the added heat. All in all, a good high stall torque converter can be one of the best performance modifications for your automatic transmission equipped Mustang!

Mishimoto Mustang Oil Cooler
Fitment includes: 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, GT, V6, Bullitt, Boss