Although the terms exhaust manifold and header are often used interchangeably, these two components are not identical, though they do serve the same basic purpose. Exhaust manifolds are typically used on regular production vehicles (e.g., your commuter car), while headers are often found on high-performance applications.
Of course, there’s more to it than that, so let’s dig a little deeper into the differences between exhaust manifolds and headers.
What is an Exhaust Manifold?
Most production vehicles have exhaust manifolds, rather than headers. The manifolds collect exhaust gases from the ports in the engine’s cylinder heads, then route those gases to the rest of the exhaust system.
Exhaust manifolds are typically made from thick cast iron. The manifolds feature short inlets, which may be of varying lengths, that come together in a single collector. Engines with a ‘V’ or flat configuration have two exhaust manifolds (one for each bank of cylinders), whereas inline or straight engines have just one manifold.
Vehicle manufacturers almost always use exhaust manifolds as original equipment because the design is durable and relatively inexpensive to produce.
What are Headers on a Car?
Now that we’ve covered exhaust manifolds, we’re left with the question—what is the purpose of headers?
Like exhaust manifolds, headers are designed to route exhaust gases from the engine to the exhaust system. The primary difference is that headers create less exhaust backpressure than exhaust manifolds, thereby allowing the engine to breathe more easily.
Headers are usually made from thin-walled stainless steel tubing. Each header features long, equal-length primary tubes that allow the exhaust gases to flow more freely than they would through an exhaust manifold.
Although some high-performance vehicles come from the factory with headers, most are added on as an aftermarket upgrade to give the car more power. You’ll usually find headers on race cars, hot rods, and other custom applications.
Recap: The Differences Between Exhaust Manifolds and Headers
Even though exhaust manifolds and headers both serve the same basic purpose—routing exhaust gases from the engine to the exhaust system—they have some key differences. Here’s a recap:
- Exhaust manifolds are typically used on regular production vehicles; headers are normally found on high-performance cars
- Exhaust manifolds are typically made from thick cast-iron; headers are usually made from thin-walled stainless steel tubing
- Exhaust manifolds feature short inlets (which may be of varying lengths); headers have long primary tubes of equal length
- Exhaust manifolds usually have heat shields; headers do not
- Headers create less backpressure than exhaust manifolds
Are Headers Worth it?
On paper, headers sound like a great idea. You just bolt a set onto your vehicle and—voila!—you have an engine that breathes better and performs better, right?
Unfortunately, it’s not that simple.
Headers usually only provide a noteworthy power gain on souped-up, high-performance engines. You’re unlikely to notice any benefit from installing a set on your unmodified daily driver.
In fact, adding a set of headers to a late-model, computer-controlled car can cause problems, such as an illuminated check engine light. Also, because most headers don’t come with heat shields, they can cause the engine compartment to become abnormally hot, creating a variety of issues.
Another factor to take into consideration is that, in some states, most aftermarket headers are illegal. You’ll definitely want to do your homework before installing a set of headers on your car.