So Fix it

Seeing a vehicle with open headers is far less common than the majority of vehicles equipped with a full exhaust system. Open headers are extremely loud, potentially illegal on public roads and most commonly used on a race track. Open headers are the optimal design for exhausting engine gasses.

Exhaust Design

A full exhaust system is made of multiple components, which release gasses exhausted from an engines combustion chamber. Starting at the engines cylinder ports, an exhaust manifold or headers direct exhaust into a front pipe that leads into a catalytic converter, which acts as a filter. Exhaust then heads into a muffler, where engine exhaust sound is muffled, and finally it releases through a tailpipe. Open headers directly exhaust gasses from the engine through piping pointed outside.

Performance

Open headers provide optimal exhaust flow and velocity while minimizing back-pressure, which smothers engine power because of the direct path from engine to the air.

DMV & Emission Testing

The Department of Motor Vehicles sets vehicle requirements that vary by state. Open headers are often illegal because harmful exhaust gasses are not filtered and delivered straight into the air. Open headers will fail emission testing. There are exceptions. For example, Delaware requires every vehicle originally equipped with a catalytic converter to have one.

Exhaust wrap, sometimes called header wrap, is lighter, more stylish and probably more efficient than heat shields. It is used mostly on motorcycles but can also be used on cars. Headers are the exhaust pipes closest to the exhaust ports on a gasoline engine. They get hot enough to ignite paper, so motorcycle riders need some protection from that heat. Fiberglass wraps insulate more efficiently than metal shields. They might even increase your horsepower. Wrap manufacturers say that keeping all that heat in the pipes improves engine efficiency.

Instructions

1

Measure the diameter of your header or exhaust pipes with a micrometer. In most cases the diameter of your header pipes will be 1 3/8 inches to 3 inches.

2

Measure the length of all the pipes you intend to wrap. Measure with a steel measuring tape from the exhaust port to the mufflers or the point where you want to stop wrapping each pipe. In most cases, this wrap is applied to V-Twin motorcycles, which have two pipes.

3

Decide the width of the exhaust wrap you want to use. Most brands of exhaust wrap come in 1- and 2-inch widths.

4

Begin calculating the length of wrap you will need per linear foot of header or exhaust pipe at 70 inches for 1-inch wrap and 30 inches for 2-inch wrap. Those lengths are the amount of wrap you need for each foot of 1 3/8-inch header or exhaust pipe.

5

Add 6 inches of 1-inch-wide wrap for each linear foot of pipe that exceeds the diameter of 1 3/8 inch diameter pipe by 1/8 inch. For example, you will need 76 inches of wrap for each linear foot of 1 1/2-inch pipe and 82 inches for each linear foot of 1 5/8 inch diameter pipe. You will need 112 inches of 1-inch-wide wrap for each linear foot of 2 1/4-inch diameter pipes and 136 inches of 1-inch-wide wrap for each linear foot of 3-inch diameter pipes.

6

Add 3 inches of 2-inch-wide wrap for each linear foot of pipe that exceeds the diameter of 1 3/8-inch diameter pipe by 1/8 inch. For example, you will need 33 inches of 2-inch wrap for each linear foot of 1 1/2-inch diameter header pipe and 45 inches of 2-inch wrap for each linear foot of 2-inch diameter header pipe.