How Torque Converters Work

Torque Converter Tech with the Proc t TCI Automotive

Stephen Kim Sep 11, 2013 0 Comment(s)
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Turbo Converters
The growing popularity of turbo cars has brought their unique converter needs to the forefront. They need lots of slippage early in a run to help spool the turbos, but need the converter to tighten up at the far end of the track to prevent excessive power loss. To accomplish this, converter manufacturers manipulate the impeller fin configuration, core selection, and stator design. These tricks result in a converter that yields both high slip just off the line, and couples tightly as a car makes its way down the track. TCI Automotive uses larger-diameter cores to obtain desirable fluid velocity in addition to employing specific clearances to yield an effective converter setup for turbo combinations.

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Tune it Yourself
Most torque converters must be cut in half to access their internals. This can be a major hassle for track cars that may need their converters opened up several times before the stall characteristics are perfectly dialed in. To address this issue, TCI Automotive's Pro-X billet aluminum torque converters feature bolt-together covers for easy servicing. The ability to simply unbolt and disassemble a torque converter has revolutionized the drag race scene. Now a racer can simply open up his torque converter and experiment with different stator designs or even replace the impeller pump while at the track. This ability to easily manipulate the behavior of the torque converter while at the track is truly invaluable for racers, allowing them to adjust their converters to suit specific conditions they face. In Outlaw 10.5 classes, a 200- to 400-rpm change in stall speed can be the difference between making a great pass and blowing off the tires. Changing the stall speed is a simple process that involves disassembling and shimming the stator closer to the turbine or closer to the pump. That means you can fine-tune your setup without the downtime involved with sending your converter back to TCI Automotive for adjustment. Furthermore, Pro-X billet converters can handle up to 3,000 hp.

Converter Diameter
The diameter of a torque converter plays an important role in its performance characteristics. The torque converter diameter establishes the moment arm, or the distance of the outer fin openings from the center of rotation. With a smaller torque converter, the fluid applies less torque to the turbine because the openings are closer to the center of rotation, thus allowing the engine to operate at a higher rpm for a given load. When the openings are moved outward—as in the case of a stock converter—the moment arm is longer, which applies more torque to the turbine for the same amount of force. This results in a lower rpm for an engine operating at a given load. Also, as the diameter of a torque converter increases, greater fluid velocities are achieved as a result of a longer fluid path and the natural effects of centrifugal force. All of these conditions explain why stock converters are typically larger in diameter and stall at lower rpm, and why racing converters tend to be smaller and stall at a higher rpm.

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Trans Fluid
The density of the transmission fluid plays a key role in determining how much force is transmitted when the fluid strikes against a surface of the converter fins. Fluids with different densities will alter the power transmission capacity and efficiency of a torque converter. At the same time, a balance must be maintained in density and heat dissipating qualities of a fluid. One vital role of the fluid is to continually dissipate heat created by the torque converter and a certain dissipating capacity is required. Likewise, the fluid must also maintain lubricity without adversely affecting transmission clutch performance. TCI Automotive recommends changing the trans fluid every 40 to 50 passes in a typical drag application. More extreme applications may require an increased frequency in fluid changes. Monitoring the appearance of your fluid between runs is a good way to gauge its health as well. TCI Automotive offers a full line of Max Shift synthetic and conventional fluids, as well as break-in fluids.

6L80E Converters
Ever since its introduction, the GM 6L80 transmission has given converter companies and enthusiasts a less-than-desirable experience. The technology used in this transmission can prove challenging and elude even the best of aftermarket tuning experts. The big news for TCI Automotive this year is the introduction of a new torque converter for the GM 6L80 transmission found in '10-and-up Camaros. TCI Automotive's new converter is equipped with several industry-exclusive features, including a high-stall, triple-disc, bolt-together lockup capabilities that do not require any tuning at all. It's a drop-in replacement for the stock converter and has all the road manners of the stock converter. Unlike the stock converter, however, it offers a much higher stall speed and significantly increased torque capacity. Furthermore, it can be completely disassembled, serviced, and even reconfigured to a new stall speed all by simply unbolting it.

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