What Are Exhaust Manifolds

What Are Exhaust Manifolds?

Exhaust manifolds are designed to couple each exhaust port of an engine’s cylinder head to a single outlet pipe. Functionally, the steely unit collects ejected waste gasses from the multiple cylinders and ejects them into a single pipe conduit. Viewed from a purely structural viewpoint, the little collector unit is manufactured as a blocky series of aligned ports. Its job is to merge the collected streams of cylinder-burnt gasses, to combine the multiple exhaust outlets into a single channel. Let’s take a closer look.

Engine-to-Exhaust System Interface

Exhaust manifolds bolt to car engines via heat-resistant gaskets. They’re the compact factory-installed workhorses that convert multiple exhaust outputs into a lone stream so that the unified volume of dirty gas can be expelled down one channel and out through a car’s tailpipe. Unfortunately, that compact profile does not favour free engine respiration. It’s a bit like dropping your head to your chest and trying to breathe freely. It just doesn’t work well, and you end up feeling breathless. An aftermarket exhaust manifold opens up output next to the point that it’s generated. As a result, that hypothetical neck is now stretching to maximize volumetric flow.

Examining the Structural Configuration

This is a critical juncture because it’s the first turn and mixing chamber encountered by the pressurized emissions after they leave the confines of the engine. Consequently, a structure that causes volumetric constriction will decrease the efficiency of the system. Certainly, the multiple output ports are properly sealed by the gasket. Their diameter is broad and the manifold chamber is fairly spacious, but the internal space defined by the contours of the manifold junction are still far from ideal. Again, back pressure problems will manifest when this engine fixture is spatially constrictive.

Accounting for Material Shortcomings

The cast iron or fabricated steel housing is capable of absorbing copious amounts of heat, but that same material will become brittle as it ages. Likewise, the coarse microcrystalline structure used by the sourced metal creates a subtle drag factor, so exhaust ejection ratios are further attenuated. In simple terms, the exhaust collecting aptitude of the product is not in question, but it’s structural and material build does place a big question mark over the collector’s backpressure minimizing capabilities.

An nth amount in and one out exhaust manifold configuration works expeditiously, but geometry improvements and material subsidization will enhance this critical juncture point. Better yet, consider looking into a header replacement if you’re really passionate about horsepower scavenging.


Trufit Exhaust
437 Warrigal Road,
Moorabbin, VIC 3189
Areas serviced: Melbourne
Tel: 03 9555 5688

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