How do I build the ultimate 13B-REW engine for a Mazda RX-7 FD?

Building a high-horsepower 13B-REW for your Mazda RX-7 (FD) is an intensive project that requires careful component matching, especially if you want to push past the 450rwhp mark.

Difficulty: Expert

Here is a blueprint for an ultimate 13B-REW single-turbo build based on proven high-performance configurations.

Engine Management

Older systems like the Haltech 1000, 1500, or HKS units are discontinued and outdated. Instead, use a modern ECU like the Haltech Elite ⁴. Alternatively, the AEM Infinity is an excellent choice for advanced features, allowing full control over flex-fuel tuning (adjusting boost and tune automatically for 91 octane through E85), drive-by-wire throttle bodies, and boost regulation based on throttle position ⁷.

Turbocharger System

For modern, efficient power delivery, the Borg Warner EFR series is highly recommended over older turbos like the T04Z.

• EFR 8374 (Internal Wastegate): An excellent choice for a responsive single-turbo FD ⁴.
• EFR 9174: Capable of pushing up to 600rwhp, though 550rwhp is generally considered plenty fast and a more realistic goal for a street-driven FD ⁴.
• If you are on a tighter budget, the Borg Warner SXE series is a solid alternative ⁴.

Fuel System (E85 Setup)

To safely run E85 at high horsepower levels, a complete overhaul of the fuel system is mandatory. A standard 255lph pump will not suffice.

• Pumps: You will need twin 460lph fuel pumps to safely support anything above 430–450rwhp on E85 ⁴.
• Injectors: For setups exceeding 530rwhp, upgrade to a 6-injector combination using an Xcessive Lower Intake Manifold (LIM). Use ID1350X injectors for the primaries and four ID1750X injectors for the secondaries ⁴. If keeping the stock LIM, running four ID1750X injectors is standard ⁴.
• Fuel Rails: Full Function Engineering (FFE) fuel components are a top choice to tie the system together ⁴.

Engine Internals & Bolt-Ons

• Internals: Ensure the rotors are properly clearanced and balanced, and use OEM Mazda 2-piece 2mm apex seals for reliable sealing ⁷.
• Trigger Wheel: Upgrade to a Full Function Engineering 36-tooth trigger wheel for highly accurate ignition timing ⁴.
• Oil Pan: Install an engine oil pan brace kit (such as the one from Banzai Racing) to reinforce the pan and prevent leaks under chassis flex and high boost ⁷.
• Water Injection: Adding a water injection kit will provide an extra margin of safety against detonation ⁴.

Supporting Upgrades

There is a massive difference between a 450hp build and a 600hp build. If you aim for the 600rwhp limit, you must upgrade virtually every supporting component, including the cooling system (radiator, FMIC/V-mount), ignition coils, and drivetrain to handle the sheer heat and torque output ⁴.