TURBO & EXHAUST MANIFOLD

A standard cast-iron exhaust manifold, especially if the turbine housing is part of it, can only handle so much heat and pressure. The build-up of heat on a standard exhaust manifold can be a problem, because it’s transferred to the engine and can lead to internal damage, especially if the engine is run at high boost for a long period of time.

A ram-style tubular stainless steel manifold is a much better alternative to a standard cast-iron manifold on some engines, such as the Vauxhall LET/LEH. The name denotes the shape of the manifold, which resembles a ram’s horns (not to be confused with a ram pipe on the induction side). The flow of the pipework (extractors) provides less back pressure, which can in some cases create more bhp.

The turbo outlet pipe can be deemed to be restrictive and, in some cases, can be replaced by a more free-flowing alternative. On the diesel-powered MG ZR/ZS and Rover 200/400 (L-series engine) for example, tuning specialist Dark Ice Designs offers a performance outlet pipe, and has found this can increase torque by 12lb ft and power output by 5bhp across the rev range.