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HOW TO BUILD A PERFORMANCE EXHAUST MANIFOLD - PART 2

 
Mandrel Bends
Components
Pipe and Tube Supply
MERGE COLLECTORS CAN HAVE A HUGE INFLUENCE OF THE EFFECTIVENESS OF A MANIFOLD. THIS MONTH WE MAKE ONE FOR A SIX-CYLINDER

Merge collector. The term sounds like a job description in the financial sector, but it’s actually a critical component of an exhaust manifold, and one where attention to detail pays big dividends. The collector is the point were the primaries join, and the angle of the merge can alter the position of peak torque in much the same was as altering primary bore and length can. It’s technology that’s been used in F1 for decades now but it’s taken a while for it to filter through to the DiY home tuning market.

A good merge collector can speed up exhaust gas velocity and that can allow running a cam with more overlap. Accuracy while fabricating is paramount as a couple of degrees error can have significant effects. And in a 4:2:1 system there are three merge collectors so it’s a time consuming job to get it right.

The components are readily available but the biggest cost is skilled labour, an area where PPC readers can produce good results by following our step-by-step guide.