Frank H. Cicerale
March 1, 2008
We swapped out the stock torque converter in this S197 Mustang for one of TCI's Super Streetfighter converters. The results speak for themselves. You can almost slip a couple of credit cards under the left front.

In today's performance world, adding power to your pushrod or modular engine has never been easier. With the advent and increased usage of power adders such as nitrous oxide, turbochargers, and both centrifugal and positive-displacement superchargers, 400-or-more rear-wheel horse-power is certainly attainable.

With the increase in horsepower output from the engine comes the need to effectively transfer the power from the crankshaft to the rear tires. While beefing up the rearend and adding a set of gears to take full advantage of the available power is on just about everyone's "to-do" list, it's just as important to be able to transfer the power efficiently through the driveline. In the case of a manual-transmission-equipped car, picking the right combination of clutch, flywheel, and transmission (and transmission gearing) is the key to leaving the starting line hard without smoking the clutch and/or wasting power. For cars that are equipped with an automatic, though, the job of making sure the power moves from the engine to the transmission, and ultimately to the rear tires, is a task handled by the torque converter.

We cruised to JDM Engineering for the converter swap. Things were kicked off when we removed the exhaust system, then unbolted the driveshaft loop from the transmission.

In this article, we will show you what an efficient torque converter is worth on the track. Pick a converter that's too tight, and the engine will struggle to get into the powerband; ultimately, the e.t. will suffer. Select one that's too loose, and the power will slip away, leaving you with poor on-track performance.

When it comes to driveline components, the torque converter is arguably the most complex part you'll choose. It is a fluid coupler, which also acts as a torque multiplier during initial acceleration. What this means is that, using the engine's torque, the converter and all of its internals multiply that torque to get the car to move out of the gate. Still, the converter can slip so the engine doesn't stall while idling in gear. Furthermore, today's converters have provisions for full lockup, and there's virtually no slippage once the vehicle is up to speed. This enhances the life expectancy of the transmission and also increases fuel mileage.

Before we delve into the innards of upgrading to a performance converter and the protocol for choosing the right one, let's take a look at what makes a converter tick.

A torque converter consists of five (or sometimes six) parts: the cover, the turbine, the stator, the sprag, and the impeller pump (and sometimes a clutch/lockup mechanism). The cover is the basic part of the converter, and in actuality, serves to contain the parts. Used for bolting up the unit, its job is to attach the converter to the flywheel. The turbine rides within the cover and is attached to the drivetrain with a spline to the input shaft of the transmission. As the transmission pump forces fluid through the converter, one turbine sends the fluid to the turbine facing it. This movement of fluid across the turbine blades is what drives the converter and the trans. Think of having two electric desk fans facing each other. Turn on one fan and it drives the blades on the other. Additionally, the amount of blades and their angle greatly affect things such as stall speed and converter flash.