5000hp 1971 Plymouth GTX: Best Transmission?

5000hp 1971 Plymouth GTX transmission. When building a high-horsepower classic Mopar like a 1971 Plymouth GTX with a 5000hp target, the transmission becomes a critical component. The original transmission won't handle that kind of power, so you'll need a robust aftermarket solution.

Choosing the right transmission for a 5000hp 1971 Plymouth GTX is paramount for ensuring the car's performance, reliability, and overall driving experience. Several factors come into play, including the engine's power curve, the intended use of the vehicle (street, strip, or both), budget considerations, and personal preferences. This article will explore the best transmission options for such a high-horsepower build, diving into the pros and cons of each to help you make an informed decision.

When dealing with an engine producing 5000 horsepower, the transmission needs to be exceptionally strong and capable of handling immense torque. Here are some top contenders for a 1971 Plymouth GTX build: — Unveiling The World Of The Eddy Edward Radio Show

1. Turbo 400 (TH400)

The Turbo 400, or TH400, is a heavy-duty automatic transmission known for its strength and reliability. It's a popular choice in high-performance applications due to its robust design and relatively simple construction.

Key Features:

• Strength and Durability: The TH400 can handle significant horsepower and torque, making it suitable for a 5000hp engine.
• Wide Availability: It's readily available and supported by numerous aftermarket companies, offering a range of parts and upgrades.
• Ease of Modification: The TH400 can be built to withstand even more power with upgraded components.
• Gear Ratios: Typically comes with a 2.48:1 first gear, 1.48:1 second gear, and 1:1 third gear.

Considerations:

• Weight: The TH400 is heavier than some other transmission options, which can slightly affect the car's weight distribution and overall performance.
• Efficiency: It's not the most fuel-efficient option due to its design and internal friction.

2. Powerglide

The Powerglide is another popular choice for high-horsepower drag racing applications. It's a two-speed automatic transmission known for its simplicity and strength.

Key Features:

• Simplicity: Fewer internal parts mean less to break, making it highly reliable.
• Strength: Can handle extreme power levels, commonly used in drag racing.
• Weight: Generally lighter than a TH400, which can be an advantage for performance.
• Aftermarket Support: Extensive aftermarket support with numerous upgrades available.

Considerations:

• Two Speeds: Only having two gears can be a disadvantage on the street, as it provides less flexibility in different driving conditions.
• Gear Ratio Spread: The large gap between the two gears can affect acceleration and drivability.

3. 4L80E / 4L85E

The 4L80E and its updated version, the 4L85E, are electronically controlled four-speed automatic transmissions. They offer a good balance of strength and drivability, making them suitable for both street and strip use.

Key Features:

• Four Speeds: Provides better gear ratio coverage compared to a TH400 or Powerglide, improving acceleration and fuel efficiency.
• Electronic Control: Allows for precise shift control and tuning.
• Strength: Can be built to handle high horsepower and torque levels.
• Overdrive: The overdrive gear helps reduce RPMs at highway speeds, improving fuel economy and reducing wear.

Considerations:

• Complexity: The electronic control system adds complexity compared to older mechanical transmissions.
• Cost: Can be more expensive to set up due to the need for a transmission controller and associated wiring.

4. Manual Transmissions (e.g., Tremec T56 Magnum)

For those who prefer the control and engagement of a manual transmission, options like the Tremec T56 Magnum are excellent choices. These transmissions are built to handle high horsepower and torque while providing a more interactive driving experience.

Key Features:

• Driver Control: Manual transmissions offer the most control over gear selection and engine RPM.
• Strength: The Tremec T56 Magnum is known for its robust construction and ability to handle high power levels.
• Gear Ratios: Multiple gear ratios allow for precise matching to the engine's power curve and vehicle's use.
• Driving Experience: Many enthusiasts prefer the feel and engagement of a manual transmission.

Considerations:

• Complexity of Installation: Swapping to a manual transmission in a car originally equipped with an automatic can be complex and costly.
• Learning Curve: Requires more driver skill to operate smoothly and efficiently.
• Cost: High-performance manual transmissions and associated components can be expensive.

5. Aftermarket Racing Transmissions

Several companies specialize in building transmissions specifically for racing applications. These transmissions are designed to handle extreme power levels and provide consistent performance under demanding conditions. Examples include transmissions from companies like M&M Transmission, Neal Chance Racing Converters, and Liberty's Gears. — Minnesota Vikings Quarterbacks: A Comprehensive Guide

Key Features:

• Extreme Strength: Built to withstand the highest horsepower and torque levels.
• Customization: Can be tailored to specific racing applications and engine characteristics.
• Performance: Optimized for quick, consistent shifts and power delivery.

Considerations:

• Cost: These are typically the most expensive options.
• Streetability: May not be ideal for street use due to their aggressive nature and specialized design.
• Maintenance: May require more frequent maintenance and specialized knowledge.

Selecting the right transmission involves considering several factors to ensure it meets your specific needs and goals.

Horsepower and Torque Capacity

The most critical factor is the transmission's ability to handle the engine's output. A 5000hp engine produces a tremendous amount of torque, so the transmission must be rated to handle at least that much, if not more, to provide a safety margin. Always check the manufacturer's specifications and consider the potential for future power upgrades.

Intended Use

The intended use of the car will significantly influence your transmission choice:

• Street Use: If the car will primarily be driven on the street, drivability and comfort are important. A transmission with multiple gears and smooth shifting characteristics, like a 4L80E or a manual transmission, may be preferable.
• Drag Racing: For drag racing, strength and consistency are key. A Powerglide or a Turbo 400, built for racing, are popular choices due to their robustness and ability to handle quick, hard shifts.
• Street/Strip: If the car will be used for both street driving and drag racing, a 4L80E or a well-built TH400 can offer a good compromise.

Budget

Transmissions can range widely in price, from a few thousand dollars for a basic rebuilt unit to over $10,000 for a high-end racing transmission. Factor in the cost of the transmission itself, as well as any necessary modifications, such as a new driveshaft, transmission cooler, or controller.

Drivability and Shift Quality

Drivability is crucial, especially for street-driven cars. Consider how smoothly the transmission shifts and how well it matches the engine's power curve. Electronically controlled transmissions like the 4L80E offer the ability to fine-tune shift points and firmness, allowing for a customized driving experience.

Installation and Modifications

Some transmissions are easier to install than others. Swapping to a different type of transmission (e.g., from automatic to manual) can require significant modifications, including changes to the transmission tunnel, crossmember, and pedal assembly. Ensure you have the necessary expertise or budget for professional installation. — New Zealand Vs USA Basketball: Who Will Win?

Aftermarket Support and Upgradability

Choose a transmission with strong aftermarket support. This means there are plenty of parts and upgrades available if you need to repair or further strengthen the transmission in the future. Popular transmissions like the TH400 and Powerglide have extensive aftermarket support, making them easy to maintain and upgrade.

If you already have a transmission in your 1971 Plymouth GTX, you might consider modifying it to handle the increased power. This can be a cost-effective option, but it's essential to ensure the transmission can be built to withstand the stress. Common modifications include:

• Upgraded Clutches and Steels: Replacing the stock clutches and steels with high-performance versions can significantly increase the transmission's torque capacity.
• Hardened Input Shaft: The input shaft is a common failure point in high-horsepower applications. Upgrading to a hardened shaft can prevent breakage.
• Valve Body Modifications: Modifying the valve body can improve shift quality and firmness, as well as allow for higher shift points.
• Transmission Brake: A transmission brake is a popular modification for drag racing, allowing the driver to build boost at the starting line.

What is the strongest automatic transmission for high horsepower?

The Turbo 400 (TH400) and Powerglide are widely regarded as two of the strongest automatic transmissions for high-horsepower applications. The TH400 is a robust three-speed transmission known for its durability, while the Powerglide is a two-speed transmission favored for its simplicity and strength in drag racing.

Can a 4L80E handle 5000hp?

A properly built 4L80E can handle 5000hp, but it requires significant upgrades. These upgrades typically include high-performance clutches, steels, a billet input shaft, and a modified valve body. It's crucial to work with a reputable transmission builder experienced in high-horsepower applications.

Is a manual transmission better for high horsepower?

Manual transmissions can be an excellent choice for high horsepower applications, offering precise control and a direct connection between the engine and wheels. Transmissions like the Tremec T56 Magnum are designed to handle substantial power levels. However, they require more driver skill and can be more complex and costly to install, especially in a car originally equipped with an automatic transmission.

How much does it cost to build a transmission for 5000hp?

The cost to build a transmission capable of handling 5000hp can vary widely depending on the transmission type, the extent of modifications needed, and the builder's rates. Generally, you can expect to spend anywhere from $5,000 to $15,000 or more for a fully built, high-performance transmission.

What are the signs of transmission failure in a high-horsepower car?

Signs of transmission failure in a high-horsepower car include:

• Slipping gears: The transmission may fail to engage or hold a gear under load.
• Harsh or erratic shifting: Shifts may be abrupt, delayed, or inconsistent.
• Unusual noises: Whining, clunking, or grinding sounds can indicate internal damage.
• Fluid leaks: Leaks can lead to low fluid levels and transmission damage.
• Burning smell: A burning odor can indicate overheated transmission fluid.

Choosing the right transmission for a 5000hp 1971 Plymouth GTX is a critical decision that impacts performance, reliability, and driving experience. Options like the Turbo 400, Powerglide, 4L80E, and Tremec T56 Magnum each offer unique advantages and considerations. By carefully evaluating your specific needs, intended use, and budget, you can select a transmission that not only handles the immense power but also enhances your overall driving pleasure. Whether you opt for a robust automatic or a controlled manual, ensuring the transmission is built to withstand the power is key to enjoying your high-performance Mopar for years to come.

If you are still unsure about the best transmission for your build, consulting with a transmission specialist or high-performance shop can provide valuable insights and guidance tailored to your specific project. They can help you navigate the complexities of transmission selection and ensure your 1971 Plymouth GTX performs at its best.