Turbo manifolds

Turbo manifolds are a central part of a turbo setup and are used to connect the engine’s exhaust side to the turbo. It is through the manifold that exhaust gases are directed from the cylinder head to the turbo’s turbine housing, where the energy in the exhaust gases is used to drive the turbo. The choice of turbo manifold therefore has a major impact on space, spool, durability and how the entire turbo setup will function in practice.

In many engine projects, turbo manifolds are chosen based on fitment, flange type and the desired build. Some solutions are made to fit specific engines and car models, while others are used in more custom-built setups where a custom downpipe, external wastegate, screamer pipe or changed turbo position is part of the build. Depending on the setup, the manifold may be made for an internal or external wastegate, and it may be designed with a focus on compact installation, better flow or more room for larger turbos.

Turbo manifolds are available in several different types and constructions. Some are cast manifolds, which often prioritise compact design, strength and OEM-like fitment, while others are welded tubular manifolds, where the focus is often more on flow, runner design and flexibility in relation to turbo positioning. Material, wall thickness, welds and flange quality are all important, especially in setups with high heat load, high boost pressure and demanding use on track, road or in motorsport.

When choosing a turbo manifold, it is important to look at more than just bolt-on fitment. The flange for the cylinder head, turbo flange, wastegate flange, turbo position, space in the engine bay and compatibility with the rest of the setup all play an important role. There can also be major differences in whether the manifold is designed for twinscroll or single scroll, whether it fits standard or modified engine mounts, and how much adaptation is required in relation to heat shielding, oil lines, water lines and the downpipe.