LS Discovery Engine Performance Information

Performance Engine Builds and Drivetrain Modifications

In our experience, the electronic ZF 4HP22 and 4HP24 in the Land Rover Discovery have been capable of handling the performance of stock GM 4.8L and 5.3L LS engines. While the Discovery LS Kit has only been tested with stock output LS engines, and many of our clients have found that the power boost from a stock LS engine to be plenty for the Discovery, some of our clients have used cams and done other modifications to get more power out of LS. We cannot guarantee the operation of parts above stock 5.3L LS power levels. However, this page lays out some general guidelines and tips for planning your build if you would like to consider this route. Most of this information also can apply to those using a stock 5.3L that want to go the extra mile.

  • The 4HP22 in the 1999-2002 Discovery is weaker than 4HP24 in the 2003-2004 Discovery. The 4HP22 has been tested with a stock 5.3 and has been capable of handling the power. However, if you want to push beyond the power levels of a 5.3, it is logical to upgrade to the 2003-2004 Discovery 4HP24 while doing the engine swap. These transmissions are readily available at junkyards and can be easily found by searching at They are typically around $300-$500. The 2003-2004 Discovery 4HP24 is the cheapest and best bolt-in transmission upgrade that can be made to the 1999-2002 Discovery's.

  • Only use cams that are designed for truck or towing applications. High horsepower cams often lose torque at low RPMs which is the opposite of what you need in a Land Rover Discovery. Typically, also high performance cams do not make much power until high in the RPM range. With the Discovery transmission shifting typically between 2000-3000 RPM and always before 5500 RPM, this power would never be used. Therefore a truck cam is the best option. Additionally, cams that require a torque converter upgrade are not recommended. Virtually all cam upgrades will require a custom tune on the GM ECM for proper operation.

  • The stock 4HP24 torque rating is 335 ft-lbs, which is about the stock rating of most Gen 3 5.3L LS engines. Pushing beyond that figure requires extra cooling. The enemy of most transmissions is heat. Adding an extra transmission cooler with or without a fan will help keep temperatures at better levels, especially if off-roading or in hot environments, and will extend the life of the transmission.

  • Conduct regular transmission fluid and filter changes.

  • Axle and differential upgrades are recommended with any power increase if using the vehicle heavily off-road.

  • If seeking the absolute best performance out of this engine and transmission combination, a standalone transmission computer upgrade is an good consideration. Such an option gives complete control over shifting patterns and line pressures to get the best performance. This may also be advisable if your vehicle has other modifications, such as large, oversized tires. ACE has used aftermarket controllers with the ZF 4HP24 on in-house builds and can provide guidance about using these products while maintaining the other electric features of the kit. This, however, is not required and can also be added at a later time.

  • There are several skilled ZF rebuilders who specialize in building these transmissions, some of which can do performance-oriented ZF rebuilds. While Discovery transmissions are known for being robust, many are aging, so if pushing an older transmission with a cammed, performance LS, budget accordingly for a future transmission rebuild.

Additionally, 5.7L and 6.0L Gen 3 LS engines are electrically and physically compatible with the kit. These engines are above the stock torque ratings of the ZF 4HP24 and have not been tested at this time. Contact us before considering these engines.

  • 6.0L LQ4 iron block: 2001-2007 Chevy Silverado 2500 (VIN Option U), must be the "short crank" model

  • 6.0L LQ9 iron block: 2002-2006 Cadillac Escalade (VIN Option N), high-compression, performance LQ4

  • 5.7L LS1 aluminum block: 1999-2004 Chevy Corvette, 2004 Pontiac GTO, requires truck accessory drive

  • 5.7L LS6 aluminum block: 2001-2004 Chevy Corvette Z06, 2004-2004 Cadillac CTS-V, requires truck accessory drive

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