The Mazda RX-8, with its distinctive freestyle doors and high-revving Renesis rotary engine, captured the hearts of enthusiasts seeking a unique sports car experience. However, the rotary's notorious appetite for oil, apex seal failures, and limited torque output have driven many owners to pursue a more robust powerplant. Enter the LS swap: the proven path to transform the RX-8 into a reliable, tire-shredding machine. While the process is well-documented, success hinges on selecting top-tier brands for the critical components. In this comprehensive guide, we explore three standout brands that deliver the core parts for a seamless RX-8 LS swap: Boss Motorsports, LSx Engines, and Melling Oil Pumps.

Planning Your RX-8 LS Swap: Laying the Foundation

Before diving into brand specifics, it's important to understand the scope of an LS swap. Converting a rotary-powered RX-8 to a GM LS V8 involves much more than dropping in a new engine. You need to address engine mounts, transmission adapters, cooling capacity, fuel delivery, wiring harness integration, and exhaust routing. The right brands simplify these challenges. This article focuses on three companies that have earned the trust of LS swappers through consistent quality and performance. Each plays a distinct role in the build, from the engine cradle to the lubrication system.

Boss Motorsports: Precision Mounting and Drivetrain Integration

Boss Motorsports has established itself as a leader in the RX-8 LS swap community. Their product line is engineered specifically for this platform, eliminating guesswork and fabrication time. For anyone undertaking this project, Boss Motorsports offers a suite of components that ensure the LS engine sits correctly and connects to the RX-8's drivetrain or a chosen transmission.

Engine Mount Kits

The foundation of any swap is a solid engine mount kit. Boss Motorsports provides custom-made brackets that position the LS engine in the RX-8 bay for optimal weight distribution and clearance. Their mounts use high-grade steel and polyurethane bushings, damping vibration while securely holding the engine. The result is a factory-like fit that simplifies header and accessory placement.

Transmission Adapters

Boss Motorsports offers transmission adapters that allow you to mate the LS engine to the RX-8's stock six-speed transmission or to common upgrade transmissions like the T56 Magnum. Their adapter plates are machined from billet aluminum and include all necessary hardware. This precision ensures the clutch alignment is correct, avoiding driveline vibrations and premature wear.

Headers and Exhaust Manifolds

Clearance in the RX-8 engine bay is tight. Boss Motorsports designs their headers specifically for LS-swapped RX-8s, routing exhaust gases efficiently without interfering with steering shafts or frame rails. Their stainless-steel headers improve exhaust flow, unlocking horsepower and torque, and are available with ceramic coating for heat management.

Additional Boss Motorsports Components

Beyond mounts and headers, Boss Motorsports offers power steering line kits, remote oil filter relocation brackets, and radiator support modifications. Their comprehensive approach means less time fabricating and more time enjoying the build. For the serious swapper, starting with a Boss Motorsports mount and header kit is a solid move.

LSx Engines: Complete Power Packages and Performance Upgrades

LSx Engines is a premier supplier of turnkey LS engine packages and performance components. They understand that an RX-8 builder wants a reliable, powerful engine ready to drop in. LSx Engines provides everything from a basic 5.3L LM7 to a fully built 427 stroker, tailored to your power goals and budget.

Complete Engine Packages

Instead of sourcing an engine from a junkyard and rebuilding it yourself, LSx Engines offers complete packages that include the engine, intake, fuel injection system, alternator, starter, and often a wiring harness. Their crate engines are dyno-tested and come with a warranty. For an RX-8 LS swap, a complete package saves significant time and ensures all components are matched.

Customization and Performance Upgrades

Every RX-8 builder has a different vision. LSx Engines provides a vast selection of camshafts, cylinder heads, intake manifolds, and fuel systems. Their technical staff can help you choose the right cam profile for street driving or track use. They also offer CNC-ported heads and custom tuning. This level of customization allows you to tailor the engine's power curve to work with the RX-8's lightweight chassis.

Technical Support and Customer Service

One of LSx Engines' greatest assets is their knowledgeable team. Swapping an LS into an RX-8 involves many small decisions—throttle cable, accessory drive setup, fuel line fittings. LSx Engines provides phone and email support to guide you through the process. Their reputation for helpfulness makes them a favorite among first-time swappers.

Why Choose LSx Engines for Your RX-8?

When you invest in an LSx Engines package, you receive a professionally assembled, performance-tested powerplant. Their attention to detail, from torque specs to gasket selection, reduces the likelihood of leaks or failures. For those wanting a straightforward path to LS power, LSx Engines delivers both product and expertise.

Melling Oil Pumps: The Heart of Your LS Engine's Lubrication

An LS engine's longevity depends on proper oiling. The factory oil pump is adequate for stock power levels, but when you're swapping an LS into a lighter car and likely pushing higher RPM or more horsepower, upgrading the oil pump is a must. Melling is a trusted name in the industry, supplying high-quality oil pumps to OEMs and the aftermarket for decades.

High-Volume Oil Pumps

Melling offers high-volume oil pumps that deliver increased flow to keep bearing surfaces cool and well-lubricated under high load. For an RX-8 LS swap, which may experience extended high-RPM driving, a high-volume pump provides peace of mind. Their pumps are engineered with precision rotors and hardened housings to withstand debris and wear.

Durability and Materials

Melling uses cast iron or billet steel gears depending on the application, ensuring the pump can handle elevated oil pressures without distortion. Their pumps are also available with a standard or heavy-duty pressure relief spring. For builds that see track time, a Melling high-pressure pump ensures consistent oil pressure even during hard cornering.

Compatibility with LS Variants

Melling oil pumps are designed to fit a wide range of LS engine configurations, including the popular LM7, L33, LS1, LS3, and LS6. They even offer pumps for the newer LT engines. When ordering, specify your engine platform. Melling's catalog is extensive, and their parts often include upgraded internal clearances for performance use.

Installation Tips for the RX-8 Swapper

When swapping an LS into an RX-8, the oil pan and pickup tube are critical for clearance and oiling. Melling pumps pair well with aftermarket oil pans designed for the RX-8 chassis. Ensure you use the correct pickup tube length and O-ring seal. A Melling pump combined with a baffled oil pan transforms the LS into a reliable track-ready engine.

Additional Components and Considerations for a Successful Swap

While Boss Motorsports, LSx Engines, and Melling cover structural, powertrain, and lubrication needs, a complete RX-8 LS swap also requires attention to cooling, fuel delivery, electronics, and exhaust.

Cooling System

The RX-8's factory radiator is insufficient for an LS V8. Many builders opt for an aluminum radiator from brands like Mishimoto or C&R Racing. Boss Motorsports offers a custom radiator support that allows a larger core to fit between the frame rails. Electric fans with a proper shroud are essential to keep temperatures in check during stop-and-go traffic.

Fuel System

An LS engine requires higher fuel flow. Upgrading to a Walbro 255 LPH in-tank pump or a surge tank with external pump is common. Ensure the fuel lines and filter are rated for the horsepower level. Braided stainless lines with AN fittings provide durability and easy routing.

ECU and Wiring

The factory Mazda ECU cannot control the LS engine. You'll need an aftermarket ECU like the Holley Terminator X or a GM Genuine ECM with a custom harness. Many companies sell plug-and-play harnesses for the RX-8 LS swap, simplifying the wiring process. LSx Engines can include a harness with your engine package.

Exhaust System

The Boss Motorsports headers terminate at a specific location under the car. From there, you need a custom exhaust system that clears the RX-8's subframe and diffuser. Many builders choose a dual 2.5-inch or 3-inch single exhaust with performance mufflers. Tuning the exhaust to your camshaft selection maximizes power and sound.

Building a Reliable RX-8 LS Swap: Tips from the Community

Thousands of enthusiasts have successfully completed this swap. The collective wisdom emphasizes a few key points: prioritize quality parts, take your time with wiring, and thoroughly test all systems before the first drive. Using proven brands like Boss Motorsports, LSx Engines, and Melling reduces frustration and increases reliability. Also, consider upgrading the clutch, flywheel, and differential to handle the increased torque. A limited-slip differential is highly recommended for an RX-8 LS.

Common Pitfalls to Avoid

Skipping the oil pump upgrade is a common mistake. The factory pump may not maintain pressure at sustained high RPM. Another pitfall is using universal engine mounts that require significant modification; Boss Motorsports mounts are specific to the RX-8 and should be your first choice. Finally, do not overlook the cooling system. An underperforming radiator will quickly overheat the LS, especially in warmer climates.

Conclusion

The Mazda RX-8 LS swap is one of the most rewarding projects a car enthusiast can undertake. By choosing the right brands, you ensure a smoother build and a more enjoyable driving experience. Boss Motorsports delivers the precise mounting and integration components you need. LSx Engines provides powerful, ready-to-run engine packages backed by expert support. Melling Oil Pumps safeguards your investment with reliable lubrication. Together, these brands form the backbone of a successful RX-8 LS swap. Whether you're chasing street performance or track day glory, investing in quality components from these industry leaders will pay dividends in reliability and fun.