Overview

FTI Performance TH400 Level 4 Transmissions TH400-4K21

Brand: FTI Performance
Manufacturer’s Part Number: TH400-4K21
Part Type: Automatic Transmissions
Product Line: FTI Performance TH400 Level 4 Transmissions
Summit Racing Part Number: FTI-TH400-4K21
UPC: 887753824790
Number of Gears: 3
Bellhousing Bolt Pattern Manufacturer: Chevy
Transmission Shift Pattern: Reverse
Valve Body Style: Full manual
Transmission Advertised Horsepower Rating: 900
Torque Converter Included: Yes
Flexplate Included: No
Transmission Controller Included: No
Wiring Harness Included: No
Transmission Cooler Included: Yes
Advertised Flash Stall Rating: 3,400–3,800 rpm
Trans-Brake Included: Yes
Lockup Compatible: No
Transmission Pan Style: Deep
Transmission Pan Material: Aluminum
Transmission Pan Finish: Natural
Yoke Style: Slip-on/bolt-on
Input Spline Quantity: 30
Input Shaft Material: Hardened steel
Input Shaft Style: TH350/400
First Gear Ratio (Automatic Transmissions): 2.43
Clutch Hub: Billet Steel
Transmission Case Style: OEM
Transmission Case Material: Aluminum
Transmission Case Finish: Black
Transmission Shield Built In: No
Flexplate Shield Built In: No
Fluid Fill Location: Case
Transmission Fluid Included: Yes
Transmission Fluid Quantity Included: 12 qt.
Dipstick Included: Yes
SFI Rating: SFI 4.1/30.1
Remanufactured: Yes
Quantity: Sold as a kit

FTI Performance TH400 Level 4 Transmissions

Overview

The FTI Performance TH400 Level 4 Transmission TH400-4K21 is a complete, race-ready transmission system engineered for serious performance enthusiasts. Designed to handle up to 900 horsepower, this kit delivers exceptional strength, precision shifting, and reliability for high-demand applications. As a result, it provides everything needed for a powerful and consistent drivetrain setup.

Performance & Components

In addition, this package includes a billet torque converter with a 3,400–3,800 rpm stall rating, optimized for aggressive launches and improved track performance. The integrated trans-brake and full manual valve body offer precise control, allowing drivers to maximize reaction times. Because of this, racers benefit from quicker launches and more consistent results.

Advanced Engineering

Moreover, the transmission features high-performance clutches and steels, a 34-element intermediate sprag, and a high-flow pump to ensure durability and efficient operation. The race-prepped case, billet forward clutch hub, and heavy-duty components further enhance strength under extreme conditions. For this reason, it is capable of withstanding repeated high-stress runs without compromise.

Applications & Benefits

Finally, this complete kit includes essential components such as performance ATF, a locking dipstick, and a full cooler system, simplifying installation and setup. Suitable for drag racing, street/strip builds, and high-powered vehicles, it offers versatility alongside performance. Ultimately, it delivers a comprehensive, high-performance solution for drivers seeking durability, control, and race-proven reliability.