Turbo Manifold Ford YB Large Primary
Ford Cosworth YB Large Primary Turbo Manifold
Developed for high-output Ford Cosworth YB combinations requiring greater exhaust-flow capacity, the Walton Motorsport Large Primary Turbo Manifold uses 42.56 mm ID primary runners to support higher-horsepower, higher-RPM and larger-displacement YB builds.
This is the higher-flow alternative to Walton Motorsport's standard YB manifold and is intended for engines where outright airflow and top-end performance justify moving away from the smaller, more response-focused primary configuration.
Ford Cosworth YB Turbo Manifold - 42.56 mm ID Large Primary Runners
The defining feature of this manifold is its 42.56 mm internal-diameter primary runners.
Increasing primary diameter provides additional exhaust-flow capacity for heavily developed YB engines operating at greater engine speeds, displacement and power levels.
The trade-off is straightforward: where the standard manifold prioritises a broader balance between gas speed, response and flow, the Large Primary shifts that balance towards high-RPM airflow and power potential.
Ford Cosworth YB Turbo Manifold - Built for Serious YB Engine Combinations
The Large Primary is particularly relevant to YB builds where increased displacement, cylinder-head flow, turbocharger capacity or sustained high-RPM operation means the standard manifold is becoming a restriction.
It is therefore not automatically the better manifold simply because the engine is modified.
For many road, rally, circuit and responsive competition combinations, the standard manifold may remain the better match. The Large Primary should be selected when the engine combination actually requires the additional runner capacity.
Ford Cosworth YB Turbo Manifold - Modern V-Band Turbo Options
The Large Primary manifold is currently configured for Garrett V-Band G25, G30 and G35 turbochargers, including GTX30 and GTX35 applications.
The turbocharger should be selected around the complete engine combination and intended powerband, particularly given the increased airflow capability of the larger-primary manifold.
Ford Cosworth YB Turbo Manifold - Wastegate & Boost Control
The manifold features a 40–50 mm external wastegate port, supplied without a flange fitted.
This allows the final wastegate specification and position to be selected around the turbocharger, boost target and vehicle installation.
Ford Cosworth YB Turbo Manifold - Important Fitment Difference
The Large Primary manifold is compatible with the Smith & Jones block, but does not fit Mk1 or Mk2 Escort applications.
That's an important distinction from Walton Motorsport's standard YB manifold, which has been specifically developed to accommodate Mk1/Mk2 Escort YB conversions subject to the documented installation modifications.
Ford Cosworth YB Turbo Manifold - Standard or Large Primary?
Choose the standard YB manifold when response, broader application compatibility and compact packaging are priorities, including Mk1/Mk2 Escort conversions.
Choose the Large Primary when the engine's displacement, RPM, airflow and power requirements justify its 42.56 mm ID runners, and the vehicle installation provides the required space.
If you're unsure which manifold is appropriate for your YB build, contact Walton Motorsport before ordering with your engine specification, turbocharger and vehicle application.
Further Questions?
Turbo Manifold Ford YB Large Primary - Garrett V-Band (G25/G30/G35, GTX30/GTX35) / 40 - 50mm Port Size (NO flange fitted) is backordered and will ship as soon as it is back in stock.
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Turbo Manifold Ford YB Large Primary
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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
