Exhaust Manifolds & Downpipes

Exhaust Manifolds & Downpipes Explained

The exhaust manifold collects the engine output gases from each exhaust port and transfers this to one outlet pipe, which in turn feeds the intermediate pipe (B-pipe). Turbocharged engines will also have a downpipe that collects the turbine output gases and feeds it into the exhaust manifold single outlet pipe. Downpipes can be catted or catless – however, the latter is illegal in certain jurisdictions – so please do check first before committing. If the engine top-end has been modified, uprated or forged, invariably the exhaust manifold will require changing too. Equally if the turbocharger unit is altered, a new downpipe is required.

Common problems

Typically made from cast iron or stainless steel, exhaust manifolds can crack under extreme heat or simply over time through wear. The exhaust manifold gaskets can perish causing the manifold to leak. Issues will manifest with either a burning smell emanating from the engine bay, an excessively noisy exhaust, and/or loss of engine power.

Thinking of upgrading?

Retrofitting aftermarket exhaust manifolds are often made from welded tubular steel, which is stronger, lighter, rust resistant and more resilient. Better design creating a less disruptive airflow can also lead to efficiency gains. Be aware that changing one or both these components will likely alter the exhaust note. Exhaust manifolds can be creative, flamboyant works of art fit for display in an automotive gallery; capable of lighting up any engine bay. Accentuating intricate pipe work with precise tig welds in an anodised blue finished titanium is the stuff of photographers dreams.