The Mazda RX-7, especially the third-generation FD3S, remains an icon of Japanese sports car engineering. Its lightweight chassis, near-50/50 weight distribution, and high-revving 13B rotary engine deliver a driving experience few modern cars can match. For many owners, the stock twin-turbo setup is just the beginning. Aftermarket turbo kits—like the renowned Greddy (Trust) system—offer a proven path to substantial power gains, better reliability, and improved drivability. In this article, we break down everything you need to know about installing the Greddy Turbo Kit on your Mazda RX-7: the real costs, the performance boosts, the installation process, and the critical supporting modifications that separate a reliable 400 hp build from a ticking time bomb.

What’s in the Greddy Turbo Kit?

Greddy kits are known for being comprehensive, high-quality packages. For the RX-7, the kit typically includes the following core components, each engineered to work together without the piecemeal headaches of a custom setup:

  • Turbocharger: Usually a Greddy T67 or T78 (single large turbo), replacing the stock sequential twins. This eliminates many of the stock system’s complexity and heat soak issues.
  • Intercooler: A large front-mount intercooler (FMIC) with cast end tanks and a bar-and-plate core, designed to lower intake air temperatures even under sustained boost.
  • Piping kit: Mandrel-bent aluminum charge pipes and intake piping, with silicone couplers and T-bolt clamps. This replaces the restrictive stock plumbing.
  • Wastegate: A Greddy Type-R or Type-S external wastegate with a preset spring pressure (usually 7–10 psi). This provides precise boost control.
  • Blow-off valve: A Greddy Type S or Type RS recirculating or vent-to-atmosphere BOV, helping prevent compressor surge and protective of the rotors.
  • Downpipe and exhaust: A stainless steel downpipe (often with a high-flow catalytic converter or test pipe) that connects to the stock or aftermarket exhaust.
  • Oil and water lines: Braided stainless steel lines for turbo lubrication and coolant flow, with all necessary fittings.
  • Fuel management hardware: Some kits include a piggyback fuel computer (e.g., Greddy e-Manage) or at least a fuel cut defender, though a standalone ECU is highly recommended.

The Greddy Turbo Kit is designed to bolt onto the FD3S RX-7 13B-REW engine with minimal fabrication. It moves the turbo position to a more efficient location, freeing up space in the engine bay and improving airflow over the engine.

Cost Breakdown: What You’ll Really Spend

The price of the Greddy kit itself is only the beginning. A realistic budget needs to account for labor, supporting modifications, tuning, and unforeseen surprises. Here’s a detailed estimate based on current market rates.

1. The Kit Price

  • New kit: $3,000 – $4,500 (depending on model and included options). Note that Greddy no longer produces some of these kits, so you may need to find new-old-stock or buy used.
  • Used kit: $1,500 – $2,500, but condition can vary widely. Look for complete kits with all brackets, hoses, and the hardware.

2. Labor Costs

  • Professional installation by a rotary specialist: $800 – $1,500 (8–15 hours at $80–120/hr). A general shop may charge less but may not understand the RX-7’s unique quirks.
  • DIY: Free, but you’ll need extensive mechanical experience, rotary knowledge, torque wrenches, and patience. Plan for at least a full weekend.

3. Supporting Modifications (Essential)

To handle the added power and ensure longevity, you should budget for these items:

  • Fuel system upgrade: $400 – $1,000. Larger fuel pump (e.g., Walbro 255 lph), upgraded injectors (750cc–1600cc), and a fuel pressure regulator are often needed. The stock fuel system is marginal at 300 hp.
  • Standalone ECU: $1,200 – $2,500. A Haltech, Adaptronic, or Power FC (now hard to find new) with harness and tuning. This is non-negotiable for reliable power gains.
  • Tuning (dyno time): $400 – $700. Including wideband O2 sensor installation and several dyno pulls to dial in the air/fuel ratios and timing.
  • Clutch upgrade: $400 – $900. The stock clutch will slip above 300 hp. A stronger twin-disc or single-disc clutch is required.
  • Cooling system improvements: $200 – $600. Larger radiator, electric fan kit, and possibly an oil cooler upgrade. The FD runs hot in stock form; adding a big turbo adds heat.
  • Boost controller and gauge: $200 – $500. A manual or electronic boost controller, plus a boost gauge and wideband AFR gauge. You need to know what the engine is doing.
  • Exhaust system (if not included): $400 – $800. A full 3-inch cat-back exhaust reduces backpressure and improves spool.

Total supporting mods can easily add $3,000 – $6,000 to the project.

4. Miscellaneous

  • Gaskets, seals, fluids, spark plugs: $200 – $400. Replace the water pump, thermostat, and gaskets while you’re in there.
  • Potential engine refresh: $1,500+ if the engine has high miles or oil seal issues. Many owners rebuild or at least replace apex seals before adding boost.

Realistic total cost range: $5,000 – $12,000 for a proper, reliable installation. The kit itself is the cheap part.

Performance Boosts: What You’ll Feel

The Greddy Turbo Kit transforms the RX-7’s character. The stock sequential turbos are laggy and complex; the Greddy single-turbo setup delivers a broader powerband.

  • Horsepower gain: With a proper tune and supporting mods (fuel pump, injectors, ECU), expect 350–450 whp (wheel horsepower) at around 14–18 psi. That’s roughly 90–160 hp over a stock FD (which dynos around 230–250 whp).
  • Torque increase: Rotary engines love torque. Gains of 80–120 lb-ft at the wheels are common. The peak torque moves to a higher RPM but the area under the curve is much larger.
  • Boost response: A T67 turbo will spool fully by 3500–4000 RPM, providing strong mid-range pull all the way to the 8500 RPM redline. The Greddy T78 spools a bit later (4000–4500) but pulls harder up top.
  • Throttle response: The single turbo eliminates the changeover from primary to secondary turbos. No more hesitation—the engine feels more linear and controllable.
  • Sound: The single turbo has a distinctive whistle and a more aggressive exhaust note compared to the stock system. The BOV and wastegate add auditory drama.

These gains make the RX-7 genuinely fast by modern standards. A well-tuned Greddy kit can match or exceed the performance of early 2000s supercars, while retaining the RX-7’s legendary handling.

Installation Process: Step-by-Step Overview

Installing the Greddy Turbo Kit is a major job. Here’s what’s involved, but note that each kit may have slight differences:

  1. Prepare the vehicle: Disconnect the battery, drain coolant and oil, and remove the stock intake, air boxes, and intercooler pipes. Remove the intake manifold for access (optional but recommended).
  2. Remove stock turbos: Disconnect the oil and coolant lines, remove the stock turbochargers (a difficult job on the FD; often requires removing the heat shields and downpipe). The OEM sequential system is notoriously tight.
  3. Install turbo oil and water lines: Route the new stainless lines from the engine block/turbo pedestal to the turbo. Use new gaskets and crush washers.
  4. Mount the new turbo: Bolt the new turbo to the cast-iron exhaust manifold (or use a Greddy manifold if included). Torque to spec.
  5. Install the wastegate: Weld or bolt the wastegate into the downpipe (or take it to a shop if you don’t weld stainless).
  6. Place the intercooler: Remove the front bumper reinforcement (or use a Greddy support bar). Mount the FMIC using brackets. Connect the charge pipes from turbo to intercooler, then to the throttle body. Tighten all couplers.
  7. Install intake pipe and filter: Route the 3-inch or 4-inch intake pipe from the turbo to a cone filter. Extend the MAF sensor harness if needed (or use speed-density with standalone ECU).
  8. Downpipe and exhaust: Connect the downpipe to the turbo, install the exhaust system (cat/test pipe, cat-back). Ensure no leaks.
  9. Electrical connections: Wire the boost controller, boost gauge, and if using a piggyback ECU, splice into the stock ECU harness. For standalone, install the new ECU harness (major job).
  10. Fuel system upgrade: Install larger injectors, fuel pump, and pressure regulator. Retune the fuel maps (or have a tuner do it).
  11. Final assembly: Reinstall the intake manifold (if removed), connect all vacuum lines, double-check all clamps and fittings.
  12. Testing: Prime the oil system, check for leaks, start the engine, and look for coolant/oil/fuel leaks. Do a base tune or load the map. Then take it to a dyno.

Professional installation at a rotary shop (Rotary Performance or similar) is strongly advised unless you have extensive wrenching experience with the RX-7.

Critical Considerations for a Reliable Build

Throwing a turbo kit on a stock 13B-REW without supporting mods is asking for trouble. The rotary engine is sensitive to detonation and overheating. Here are the non-optional items to consider:

  • Engine condition: Before adding boost, perform a compression test. If the engine has below 6 kg/cm² compression in each rotor face, plan for a rebuild. Many owners budget for a mild street port and fresh seals.
  • Fuel system: The stock 550 cc injectors cannot support more than ~300 whp. Upgrade to at least 720 cc primary and 1000 cc secondary, or go with 1600 cc or larger for E85. A surge tank or modified fuel pump basket is recommended to avoid fuel starvation on track.
  • Tuning: Do not run the Greddy kit on the stock ECU. Use a standalone ECU (like a Haltech Elite 2500 or Adaptronic Select) with a professional rotary tune. The stock ECU cannot adjust timing for boost.
  • Cooling: The FD’s stock cooling system is marginal from the factory. Add a Koyo radiator, high-flow thermostat, and possibly a higher-capacity oil cooler. Consider venting the hood to extract heat.
  • Drivetrain: The stock clutch will not hold 400 whp. Upgrade to a properly rated clutch (ACT, Exedy, OS Giken). The 5-speed transmission is strong enough for up to 500 whp, but the differential mount and driveshaft may need reinforcement for aggressive driving.
  • Legal and insurance: Check your local emissions laws. In many regions, removing the catalytic converter or changing the ECU will fail smog. Notify your insurance company about modifications; otherwise, claims may be denied in an accident.

Common Myths and Questions

“Will the Greddy Turbo Kit make my RX-7 more reliable?”

Indirectly, yes. The stock sequential turbos are complex, prone to failure (boost control, cracking y-pipes, etc.), and create extreme engine bay heat. A single turbo setup eliminates many failure points and reduces heat soak. However, the added power stresses the engine; reliability depends entirely on the tune and supporting mods.

“Can I install it myself if I’m good with a wrench?”

Possible, but you’ll need special tools (e.g., a fuel line disconnect tool, a rotary-specific compression gauge, a timing light). You also need access to a welder for the wastegate and downpipe modifications. Most DIYers should budget for a shop to finish the exhaust and tune.

“What boost level can I run safely?”

On a stock block (unported, no studs), keep boost at 12–14 psi with conservative timing. Above 15 psi, you risk blowing the apex seals, especially if the engine is high mileage. With a street port, stronger side irons, and proper cooling, 18–20 psi is possible on pump gas (pump 93 octane or E85).

Conclusion: Is It Worth It?

Installing the Greddy Turbo Kit on your Mazda RX-7 is one of the most rewarding modifications you can make. The gains in horsepower and drivability—combined with the legendary handling of the chassis—create a truly exhilarating driving experience. The total cost (kit + labor + supporting mods) typically ranges from $5,000 to $12,000, which is a significant investment but often less than the cost of a fully built engine swap. For the dedicated enthusiast who understands that a turbocharger is only as good as the tune behind it, the Greddy kit offers a proven, well-engineered path to making your RX-7 faster, more responsive, and more reliable than the factory setup. Do your research, budget for the extras, and hire a rotary specialist if you’re not one yourself. The result is a car that will put a smile on your face every time you hit boost.