What are some ways to reduce the weight of a Mazda RX-7 FD?

There are many ways to shed weight from a third-generation Mazda RX-7 (FD), ranging from simple removals to more involved modifications. Depending on whether you want to maintain a comfortable street car or build a dedicated track weapon, here are several actionable options:

Easy & Free Removals (Difficulty: Easy)

• Trunk & Accessories: Remove the spare tire, jack, rear wiper motor, washer bottle, and rear speakers ⁴.
• Engine Bay Details: Remove the under-hood sound deadening and unbolt the engine lift points, which can be stored until you actually need to pull the engine ⁴.

Interior & Body (Difficulty: Moderate)

• Carpet & Plastics: Strip out the rear divider, interior storage bins, and hatch plastics ⁴. You can also swap the factory carpet, which has a very heavy rubber backing, for a lighter aftermarket option to save weight while retaining a stock appearance ⁴.
• Airbag: The passenger airbag is quite heavy and can be gutted to create a storage area or an ECU mount ⁴.
• Windows: Swap the heavy glass rear hatch for a Lexan window, which can be sourced from vendors like Mazda Motorsports ⁴. However, avoid using Lexan on the side windows for street cars; unlike tempered glass, Lexan does not shatter, making emergency escapes extremely difficult ⁴.

Engine Bay, Drivetrain & Systems (Difficulty: Moderate to Hard)

• A/C & Power Steering: Deleting the air conditioning and power steering systems is a common way to drop significant weight quickly ⁴.
• Turbo Setup: Converting from the factory sequential turbos to a single turbo setup will shed the weight of the extra piping, valves, and heavy sequential manifold while opening up room for more power ⁴.
• Rotating Mass: Installing an aluminum driveshaft (which saves roughly 13 lbs) and a lightweight crank pulley greatly reduces rotating mass, providing a very noticeable improvement in engine response ⁴.
• ABS & Brakes: Deleting the ABS system not only saves weight directly but also allows you to remove the wheel speed sensors and almost the entire floor wiring harness ⁴. You can also install a brake booster delete kit, such as the one from Chase Bays ⁴.

Wheels & Unsprung Weight (Difficulty: Easy)

• Upgrading to lightweight wheels significantly reduces rotational mass and unsprung weight, helping acceleration and cornering. Options like 17" Enkei RPF1s or Work Meisters (weighing around 17 lbs each) are excellent choices compared to heavy aftermarket 18" or 19" wheels ⁴. Keep in mind that the stock FD 16" wheels are already incredibly light at roughly 14 to 16 lbs, so ensure your aftermarket choice is an actual improvement ⁴.

Electrical System (Difficulty: Moderate)

• Battery: Swap to a lightweight battery, such as a PC680, Miata battery, or a Lithium-ion unit. Just note that Lithium-ion batteries may require you to plug the car into a tender if it sits for extended periods ⁴.
• Wiring: Stripping down the factory wiring harnesses by removing unused wires, unneeded tape, and heavy connectors for deleted accessories can easily drop 15+ lbs ⁴.