Racing Exhaust

Increase airflow through an engine and it will make more horsepower. Reduce restriction on the intake side with a free-flowing air intake, larger carburetor or throttle body, and large runner intake manifold, or use forced induction with a turbocharger and supercharger, and much more oxygen will be crammed into the combustion chambers. With more oxygen you can burn more fuel and create more force driving the pistons, and therefore make more power. But just as the human body must exhale carbon dioxide, an engine has to get rid of the spent combustion gases through the exhaust. Reducing restriction on the exhaust side with the right exhaust system components not only prevents a bottleneck that can reduce airflow and power, if done properly it can actually improve flow into the cylinders for even more power production.

It’s easier to reduce exhaust restriction on a race car because in most cases an exhaust system with components to reduce noise and control exhaust emissions is not required. The remaining components that would impede exhaust flow must be replaced, so headers are installed in place of the factory exhaust manifolds because the stock manifolds are restrictive and flow poorly. Header construction consists of individual tubes, one for each exhaust port, that all meet in a larger tube called a collector. The individual tubes allow exhaust pulses to flow unobstructed from the cylinder head. All header tubes are mandrel bent. Mandrel bending ensures smooth bends and makes sure the tube maintains its size and shape throughout the entire length. Tubes that aren’t mandrel bent can lose a percentage of their diameter in sharp bends, which creates exhaust flow restriction. Mandrel bending provides consistent bends, so exhaust flow is uniform throughout the entire length of the tube. But while the primary goal is to reduce restriction and increase flow, headers have still another benefit.

Well-designed headers produce a “scavenging” effect. When an exhaust gas pulse exits a header tube into the collector, a negative pressure wave is created that travels back up the header tube to the exhaust port during valve overlap. This negative pressure helps pull any remaining exhaust gas from the cylinder and helps draw the incoming intake charge into the cylinder. Because the tubes empty in a collector, this negative pressure can also help pull exhaust gas from other cylinders. This, of course, is very beneficial to engine performance but the tubes must be the right diameter and length for scavenging to be effective during the desired rpm range, and ideally, all tubes should be approximately the same length. Larger tubes are generally better for high rpm, and smaller tubes for maintaining exhaust gas velocity for low end torque. The scavenging effect is usually most pronounced on full length, long tube headers.

Our headers come in plain steel, aluminized steel, stainless steel and titanium. Steel headers will not last very long unless they are coated. Some steel headers come with a durable ceramic coating, but others may just have something to keep them from rusting in the box. The latter must be painted with high temperature paint before they are installed, but even that kind of paint won’t last however, and they must be periodically recoated, or they will rust away. Stainless steel headers will not rust but they will usually turn blue near the head flange. A quality set of headers will have a substantial head flange to prevent exhaust leaks and all connections will have high quality welds.

However, if you don’t see exactly what you’re looking for in our header selection, or have a custom build in mind, we have the components that can make it easier to build your own, including header plates and flanges, and header collectors. We also offer header wrap that can reduce underhood temperatures and keep heat within the headers to improve exhaust flow speed and the scavenging effect. And because some tracks have muffler requirements and decibel restrictions, we can supply you with racing mufflers. Our selection includes header mufflers, collector adapters, exhaust pipes, clamps and hangers for exhaust system building.