T4 EFR Twin Scroll Manifold
The world's only cast twin scroll turbo manifold for the Mazda MX-5, made in-house from NiResist D5S Type 2 for BorgWarner EFR T4 internal wastegate turbos.
Made by Kraken
Built in our own European workshop, start to finish.
Shipped by road or air
Dispatched to the UK, fully tracked.
- If it fails, we replace it→
If a part we made fails, we make you a new one.
Questions about fitment?
Send us a message →T4 EFR Twin Scroll Manifold
£500.00
Complete kit
Build the complete kit
This part is also in the Turbo Kit Builder. Configure a full bolt-on system and order it in one go.
Open the kit builder →The Only Cast Twin Scroll T4.
The T4 twin scroll manifold is cast in-house from NiResist D5S Type 2, a high-nickel iron rated for the sustained heat and thermal cycling a turbine flange endures. It is cast as one piece, with the runners paired 1-4 and 2-3 to feed two separate scrolls. This is the only cast true twin scroll T4 manifold made for the MX-5, and its 38mm runners flow enough to support over 600 bhp.
Cast In NiResist D5S
The T4 is cast in-house from NiResist D5S Type 2, a high-nickel iron used for turbine housings and exhaust manifolds, providing resistance to cracking under sustained heat. Each manifold is cast as one piece, avoiding the runner-to-runner joints a fabricated manifold relies on.
1-4 / 2-3 Runner Pairing
The runners are paired 1-4 and 2-3 to feed two separate scrolls, keeping the exhaust pulses from interfering and allowing for faster spool. The 38mm runners flow enough to support over 600 hp, matched to BorgWarner EFR 6258, 6758 and 7163 turbos with a T4 inlet and internal wastegate. The manifold mounts top-side and retains air conditioning and power steering. Mounting the turbo on top keeps the studs in compression rather than under the cantilevered load of a side-mounted turbo. The supplied stainless steel studs and nuts are sufficient; Inconel is not required.
Performance
On a Dyno Dynamics rolling road, this T4 twin scroll build recorded 343.1 kW (460 hp) and 539 Nm at around 27 psi. Boost was in by 3,000 rpm, with power climbing to redline. Figures vary with turbo and tune.
Specifications
Manifold Questions
Which turbos fit this manifold?+
BorgWarner EFR 6258, 6758 and 7163, with a T4 inlet and internal wastegate.
Does it fit the NA and NB MX-5?+
Yes. It fits the Mazda MX-5 NA and NB, both the 1.6 and 1.8 engines.
Do I need an external wastegate?+
No. The EFR turbo has an internal wastegate.
Does it clear air conditioning and power steering?+
Yes, both are retained.
What is included?+
A stainless steel gasket and four 10mm stainless steel studs and nuts.
Do I need Inconel studs?+
No. The turbo mounts on top of the manifold, keeping the studs in compression rather than under the cantilevered load of a side-mounted turbo. The supplied stainless steel studs and nuts are sufficient.
What is NiResist D5S?+
A high-nickel cast iron used for turbine housings, providing resistance to exhaust heat and cracking.
Shipping & Returns
Worldwide Shipping
Orders to the UK ship by road or air. Every order is tracked.
Returns
Unused items in original packaging may be returned within 14 days of delivery. Custom-built or configured kits are non-returnable. Contact us to arrange a return.
Warranty
If a part we make fails, we make you a new one.
