Torque Converter Selection - CHP How It Works

Driveline Pros At TCI And Pro Torque Offer Hard-Hitting Insight On Torque Converter Selection & Design.

Stephen Kim Nov 12, 2010 0 Comment(s)
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Joe Rivera: "A performance torque converter is usually the best bang for buck mod for a hot rod. Our customers with 2010 Camaros are picking up four- to six-tenths in the quarter-mile with one of our high-stall converters. It's hard to match that with a set of headers, or a cold-air induction system. It's not that a performance converter makes more power, but what it does is allow your car to transfer power better. By raising the stall speed, or slippage, a performance converter raises engine rpm at launch, which increases power at launch. For example, if an engine makes 100 lb-ft of torque at 1,500 rpm and 175 lb-ft at 2,500, which would you rather have? With a higher-stall converter, your engine isn't making any more power, but it's allowing the motor to get to a place where it's happier more quickly. OE converters follow a one-size-fits-all philosophy. They want grandma to be able step on the gas without the tires spinning. Performance enthusiasts don't want that. They want more power to reach the wheels quicker. As a result, new-car manufacturers stick with conservative stall speeds to prevent you from going WOT in First gear and frying the tires. On the other hand, aftermarket manufacturers want you to fry the tires. When tuning a converter, the goal is to match it to the operating range of the engine. If you have a converter that's closely matched to the engine's dynamics that gets it into the fat part of the powerband more quickly, it will transfer power to wheels more quickly, which translates to faster acceleration."

1012chp_08_o Torque_converter_selection Gear 2/4

Converter Components Stanley Poff: "To the untrained eye, a torque converter may look like a big circle with a bunch of fins inside it, but the various components it contains all serve important functions. GM converters can be broken down into two basic groups: non-lockup converters used in the TH350 and TH400, and lockup converters used in overdrive transmissions like the 700-R4, 200-4R, 4L60, 4L65, 4L80, and 4L85. The main components in a conventional non-lockup converter are the mounting cover, turbine, stator, and pump impeller. The mounting cover is what bolts to the flexplate and acts as a housing for all the internal parts. The pump impeller pumps and circulates fluid through the torque converter. As engine rpm increases, the rate of fluid flow through the converter increases until it reaches lockup. The turbine then catches the fluid from the pump impeller and circulates it to the stator and finally back to the pump, in a circular motion. By directing fluid from the turbine back to the pump impeller, the stator is responsible for the stall speed and torque multiplication of the converter. In addition to those four components, lockup converters add a lockup piston to the mix, which enables the converter to lock up at cruising speed. Once the engine reaches a certain temperature and rpm, a solenoid located on the transmission activates the lockup function."

Joe Rivera: "Data acquisition is the key to understanding and improving performance in all areas of racing. The same is true in the development and tuning of performance torque converters. The many years of racing and street car development we have been a part of has allowed us access to some of the best testing equipment available today, from high-end race data acquisition systems to rear-wheel dyno equipment. Even so, it's the race car that is the ultimate test for what we're doing.


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