Turbo Manifold Mazda Rotary 13B - RX7 FD
Mazda RX-7 FD 13B Twin-Scroll Turbo Manifold
Developed specifically for Mazda RX-7 FD 13B rotary applications, the Walton Motorsport 13B Turbo Manifold provides a large-flow, twin-scroll turbo platform designed around the unique exhaust characteristics of the rotary engine.
Using a divided T4 turbo flange, large 54.76 mm ID runners and twin external wastegates, the manifold is aimed at serious single-turbo FD builds where exhaust flow, boost control and turbocharger performance are the priorities.
Mazda 13B Turbo Manifold - Divided T4 Twin-Scroll Configuration
Unlike a conventional four-cylinder manifold feeding into a merge collector, the 13B manifold uses two separate primary paths feeding directly into a divided T4 turbo flange.
Keeping the exhaust paths separated removes the need for a conventional collector and maintains the divided turbine inlet configuration all the way to the turbocharger.
For a high-output 13B single-turbo build, this provides a simple, high-flow exhaust path while allowing the turbo system to take advantage of a twin-scroll turbine housing.
Large 54.76 mm ID Runners
Rotary engines move a substantial volume of hot exhaust gas, particularly as boost, engine speed and power increase.
The manifold uses 54.76 mm internal-diameter tubing, tapering into the divided T4 turbo flange to provide the exhaust-flow capacity required for serious 13B applications.
The existing design is specifically listed as suitable for BorgWarner S300-series turbochargers, making the intent of the manifold clear: this is a large-frame single-turbo solution rather than a small response-oriented street manifold.
Mazda 13B Turbo Manifold - Twin External Wastegate Boost Control
Each side of the divided manifold has its own 40 mm external wastegate connection, with both V-band wastegate flanges fitted.
The twin-wastegate arrangement maintains wastegate control across both sides of the divided exhaust system and provides high wastegate priority for accurate boost management.
The manifold is optimised around twin Turbosmart Gen-V CompGate40 wastegates, providing a matched boost-control solution for the twin-scroll arrangement.
Mazda 13B Turbo Manifold - Optional Twin Screamer Pipes
Walton Motorsport also offers a matching set of twin 40 mm screamer pipes for the RX-7 FD manifold.
These can be selected with the manifold to complete the wastegate discharge side of the system and are designed around the manifold's twin CompGate40 configuration.
Building Your FD Mazda 13B Turbo System
This manifold is intended as the foundation of a serious single-turbo 13B FD combination.
Turbocharger selection, wastegates, downpipe, intake, charge system, fuel system and engine management should all be specified around the engine build, intended boost level and how the car will be used.
For customers planning an RX-7 FD single-turbo conversion and unsure whether the divided T4/S300-style configuration is appropriate for their engine and power goals, contact Walton Motorsport before ordering and we can help establish the appropriate specification.
Further Questions?
Turbo Manifold Mazda Rotary 13B - RX7 FD - T4 Twin Scroll / Twin 40mm Port (Flanges Fitted) is backordered and will ship as soon as it is back in stock.
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Turbo Manifold Mazda Rotary 13B - RX7 FD
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Built to Last. Backed for Life.
A lifetime warranty is easy to offer. Building a turbo manifold that's unlikely to ever need it is the hard part.
You can find the full details of the Walton Motorsport Warranty HERE
Every Walton Motorsport manifold is engineered to withstand the extreme temperatures, vibration and abuse that come with high-performance street and race applications. From material selection and fabrication to our cast collectors and proven designs, durability is built into every product.
The biggest inconvenience of a failed manifold isn't the repair—it's the downtime, the labour to remove it, and the event or track day you might miss. That's why our focus has always been on preventing failures before they happen, not simply replacing parts after they do.
We're proud to stand behind every manifold we manufacture with a Lifetime Warranty. While no mechanical component is indestructible, our goal has always been simple: build products that earn your trust by performing reliably for years to come.
Because when you choose Walton Motorsport, the last thing you should be worrying about is your manifold.
Material Selection
Every Walton Motorsport manifold starts with carefully selected 304 stainless steel tubing. Not all 304 stainless is manufactured to the same standard, and the quality of the tubing plays a critical role in the durability of the finished product.
Turbo manifolds are subjected to thousands of extreme heat cycles throughout their life. Lower-quality tubing can fatigue over time, and we've seen inferior materials crack or split along the welded seam under these conditions. That's why we specify the exact tube grade and wall characteristics we know will perform reliably in demanding street and motorsport applications.
Our cylinder head flanges are designed in-house and precision cut using modern fibre laser technology, providing exceptional dimensional accuracy and repeatability. Compared to traditional CO₂ laser cutting, fibre laser cutting delivers cleaner edges and tighter tolerances, ensuring an accurate fit and consistent sealing.
Manufacturing Process
Port-Matched Flange Construction
Rather than simply welding the runners to the face of the flange, Walton Motorsport machines each runner to pass through the flange before it is TIG welded from both sides. The ports are then hand-finished to produce a smooth, uninterrupted transition from the cylinder head into the runner.
This manufacturing method delivers several important advantages:
- Increased weld strength and long-term durability.
- Improved gas flow by eliminating abrupt transitions.
- A smoother change from the oval exhaust port to the round runner.
- Reduced turbulence for improved exhaust efficiency.
The result is a manifold that is stronger, flows better, and is built to withstand years of hard use.
Cast Merge Collector
At the heart of every Walton Motorsport manifold is our proprietary cast merge collector, designed entirely in-house.
Our latest collector design delivers the highest wastegate flow we've achieved while maintaining excellent merge efficiency into the turbine. The internal geometry provides smooth gas transitions, minimising turbulence and helping to reduce exhaust gas temperatures without sacrificing performance.
Unlike fabricated collectors assembled from multiple sections, our one-piece cast design eliminates internal joints and welds within the collector itself. This not only optimises gas flow but also significantly improves structural integrity, reducing the likelihood of collector failures that can damage turbochargers or engines.
Every design decision is made with the same objective: maximum performance, exceptional durability, and complete confidence when pushing your engine to its limits.
For a deeper look at our engineering philosophy and manufacturing methods, visit our Technical Centre.
Proven Motorsport Experience
In every Walton Manifold
