The Mechanics and Merits of a Lockup Torque Converter in Drag Racing

‍Drag racing, the epitome of speed and power, is a sport continuously challenged by technology. One such innovation is the lockup torque converter, an automatic transmission component designed to enhance performance and fuel efficiency. As a drag racing enthusiast, you might be wondering whether using a lockup torque converter is beneficial for your vehicle. This article aims to answer that question, offering a detailed exploration of lockup torque converters and their pros and cons in the world of drag racing.

Understanding Torque Converters

Before we delve into lockup torque converters, let’s first understand what a torque converter is. Essentially, a torque converter is a device that transfers rotating power from an engine, or the prime mover, to a rotating driven load. This fluid coupling device serves as a mechanical clutch, separating the load from the power source.

A torque converter’s main characteristic is its torque multiplication ability, which comes into play when the output rotational speed is relatively low. This multiplication effect is facilitated by the fluid from the converter’s curved vanes deflecting off the stator.

Traditional Torque Converters and Their Drawbacks

Traditional torque converters were notorious for causing RPM slippage of fluid between their turbine and impeller. This slippage led to oil turbulence, which in turn generated heat – detrimental to both the converter and transmission. To mitigate this, car manufacturers used air vanes positioned outside the torque converter to cool the oil. However, this mechanism only found limited success in small vehicles.

The Advent of Lockup Torque Converters

Lockup torque converters were introduced to tackle the issue of heat generation and improve fuel efficiency. These devices feature a clutch that locks the engine to the transmission input shaft, leading to a direct 1:1 drive ratio.

The locking mechanism, often operated hydraulically, enables the torque converter components to serve as a rotating flywheel mass. This reduces the load on the radiator and promotes fuel economy.

Lockup Torque Converter Failure Indicators

A lockup torque converter can fail in various ways. It can remain locked up, causing the engine to stall when the car is braked. Alternatively, it may not lock at all, leading to increased fuel consumption and radiator temperature. The converter can also slip when engaged, allowing the engine speed to rise at a constant speed.

Lockup Torque Converters in Drag Racing

In drag racing, the use of lockup torque converters has become a topic of debate. Some believe that these devices offer an advantage over manual transmissions, while others argue that they hinder performance.

Pennsylvania-based Transmission Specialties, a pioneer in manufacturing lockup converters for high-end drag racing, has over 30 years of experience in the market. They believe that lockup torque converters offer a distinct advantage in racing, particularly in Pro Modified, Pro Street, and other high-powered machines.

On the other hand, many racing bodies, including the NHRA, have banned the use of lockup torque converters, citing safety and performance reasons. This has led to a pushback from manufacturers and racers who believe that these devices offer no advantage over clutch-equipped cars.

Pros and Cons of Using a Lockup Torque Converter in Drag Racing

There are several advantages and disadvantages associated with using a lockup torque converter in drag racing.


  1. Fuel Efficiency: A significant advantage of using a lockup torque converter is its contribution to fuel economy. When the converter locks, it reduces the slippage, leading to less fuel consumption.
  2. Reduced Heat Generation: By reducing slippage, lockup converters also minimize heat generation, reducing the risk of overheating and subsequent damage to the transmission.
  3. Improved Performance: Some racers have reported enhanced performance when using a lockup torque converter, particularly in terms of acceleration and top speed.


  1. Complexity of Operation: Operating a lockup torque converter can be more complex than a traditional converter, requiring additional control mechanisms and careful management.
  2. Risk of Failure: As mentioned earlier, lockup torque converters can fail in a number of ways, potentially leading to performance issues and even damage to the vehicle.
  3. Regulatory Restrictions: Perhaps the most significant drawback for drag racers is the fact that many racing bodies have banned the use of lockup torque converters.

The Verdict: To Lockup or Not?

Whether or not to use a lockup torque converter in drag racing depends on a variety of factors, including the specific regulations of the racing body, the exact requirements of the vehicle, and the personal preferences of the driver. While lockup converters can offer advantages in terms of fuel efficiency and reduced heat generation, they also come with their own set of challenges and potential risks.

In conclusion, lockup torque converters are a technological innovation that has the potential to enhance the performance and efficiency of drag racing vehicles. However, their usage should be carefully considered, keeping in mind the specific requirements and constraints of the sport.

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