The stainless steel six-branch tubular exhaust manifold replaces the standard two-piece cast iron manifold with individual primary pipes for each of the six cylinders. Each primary pipe is tuned in length and diameter to optimise exhaust gas scavenging, the process by which the vacuum created by the departing exhaust pulse from one cylinder assists in drawing the exhaust gases from the next cylinder in the firing order. On a six-cylinder engine with its overlapping exhaust events, the potential for pulse interference in a standard manifold with shared collectors is significant, and the six-branch design addresses this directly by giving each cylinder its own dedicated primary pipe before the gases merge in a common collector.
Practical Benefits
The practical improvements are a noticeable increase in mid-range torque and throttle response, smoother power delivery throughout the rev range, and a more characterful exhaust note that is distinctly six-cylinder, deeper and more purposeful than the sound through the standard cast iron manifold. The stainless steel construction provides complete corrosion immunity, cast iron manifolds develop surface rust and can crack at stress points around the port flanges, particularly if the cylinder head studs are over-tightened or if the manifold has been subjected to repeated thermal cycling over many years of use. A cracked cast iron manifold causes an exhaust leak that is audible as a ticking or blowing noise at the head face, accompanied by a localised sooty stain on the cylinder head.
Fitting and Compatibility
The manifold bolts directly to the cylinder head using the standard fifteen studs shared between the inlet and exhaust manifolds, and connects to the existing front pipe assembly via the standard manifold-to-pipe flange and seals. The stainless manifold is compatible with both the standard mild steel exhaust system and the Club stainless steel exhaust system. For the best results, a stainless manifold paired with a stainless exhaust system provides a complete corrosion-free exhaust path from cylinder head to tail pipe, eliminating every potential point of exhaust deterioration. The combination of improved gas flow from the six-branch manifold and unimpeded flow through the stainless exhaust system delivers the maximum performance benefit available from the exhaust side of the engine.