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Exhaust headers are one of the most popular performance components available, and they’re often the first modification people make to their cars. Their relative simplicity makes them a great starting point for experienced car builders and novice enthusiasts alike. That said, there are a lot of choices when it comes to headers, any of which can affect the performance, appearance, and ease of installation.
One of the most obvious choices you’ll have to make is what style of header. It’s easy to get lost when you’re wading through block huggers, lakesters, shorties, uprights, fenderwells, long tubes, mid-lengths, and turbo headers. These all have their place but for most people the big question to answer centers around length i.e. shorty versus mid-length versus long-tube. These three designs solely address power production while the others are more aesthetically motivated.
While power production is of prime importance, fitment is just as critical – if you can’t install a set of headers, it doesn’t matter how much additional performance they provide. Some header styles tend to be easier to install than others. At the same time, quality becomes a factor – superior design and manufacturing means superior fitment. Headers have to deal with items like steering components, clutch cable clearance, cross member, inner fender, starter, shifter mechanism interference, and transmission clearance. And if you’re swapping a motor into a non-original platform these interference scenarios can increase exponentially.
Headers make their power by reducing backpressure in the exhaust system, increasing the volumetric efficiency of the engine. The reduction of back pressure triggers a scavenging effect. In the firing cycle of an engine there is a time at the end of the exhaust stroke when the intake and exhaust valves are both open. It’s called valve overlap. The effect creates a low-pressure area behind the initial pulse (high pressure) of exhaust gases that helps to evacuate exhaust gases from the combustion chamber while also expediting the filling of said chamber with the incoming air/fuel mixture. The complex dynamics of all these factors come into play when choosing between the extremes of long tube and short tube headers,
Don’t be misled by their name, shorty headers can have a great deal more primary tube length than the clumsy OE iron manifolds they replace. Some stock manifolds, like those on modern Mustangs, barely exit the flange before being turned and directed to the exhaust system, tight turns equal more restriction. Worse still, some engines run log-style exhaust manifolds where spent gases exit the head into a crude plenum before being pushed into the exhaust system. These designs can cause all kinds of flow and pressure challenges.
Some shorty headers have twisted tubes within their small footprint while others have runners that flow straight to the collector in a more traditional manner. Both types offer better than stock performance. Beyond any increase in primary pipe length, the performance improvements of shorty headers can be attributed to their tubular construction which provides flow benefits over OEM units. Typically, shorty headers generate better low to mid-range torque compared to stock offerings. Shorty headers are also quieter than the other designs. At the same time, shorty headers tend to be the easiest headers to install.
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Mid-length headers play the midrange game, providing some of the benefits of a long-tube header without inducing their fitment headaches. They're also a great way to avoid ground clearance issues because they position the collector and other key components up above the chassis rails. While you get the added primary tube length, the collector on this design is typically shorter, which can impact the unit’s tunability. Mid-length headers improve performance by making additional horsepower in the mid- to upper-rpm range versus stock. This style of headers is typically about as easy to fit as shorty headers, and tends to be a much simpler installation than long-tube headers.
Long-tube headers make their power in the mid- to high-RPM range and are superior to both stock and most aftermarket shorty headers. If you can get long-tube headers to fit, you’ll usually realize the most power gains. And that part about fitment is no small thing. Long-tube headers are typically the most challenging to install; in many cases they require you to temporarily remove engine-mount bolts to raise the engine for additional clearance. Or you may have to unbolt various components, slide the headers in place, and then reinstall those parts. The specific steps can vary from car to car, and may even be different from one side of the engine to the other.
The added length of long-tube headers enhances their ability to reduce backpressure and increase volumetric efficiency. As the exhaust pulse travels down the long runners the timing of when it reaches the collector is controlled, or tuned, by the length of the runners compared to one another. The pulses are ‘timed’ to arrive at separate moments to avoid colliding and creating a restriction, which forces the engine to pump the exhaust gases out – an unwanted occurrence often called a pumping loss.
Long-tube headers come in two distinct flavors, 4-into-1 and Tri-Y. The 4-into-1 design is the most common. In a V8 application, one bank of the header features four primary tubes that run from the mounting flange to a single collector. A Tri-Y long-tube header pairs cylinders that are synchronized from a firing order standpoint. From the exhaust port the paired cylinders have tubes that join each other and become a single tube via a 2-to-1 collector or as joined pipes. This tube then runs to the main collector where it merges with the other pipes.
The 4-into-1 is the top-end terror of the two long-tube designs, making its presence felt high in the rpm range. In contrast, a traditional Tri-Y shows better in the mid-range versus the 4-into-1, but loses some power in the upper RPM range. Even so, both styles of long-tube headers perform better than stock, mid-pipe, and shorty headers.
Despite it being a critical part of header performance, we chose not to focus on tube diameter here. The rule of thumb is that smaller primary and secondary tubes produce better low-end torque while larger primary and secondary tubes produce better top-end horsepower. Size is also critical in collector design as overall length, exit diameter, and the shape of the collector and whether it terminates in a mild taper, or convergent or divergent end piece will all impact performance.
There has never been a swap engine that’s too small for its new home. So, all swap-oriented products are all about size reduction and compact design – the more compact the better. Along with oil pans, intakes, and accessory drives, headers represent a space saving opportunity. Beyond width, the collector is a point of contention. A header that fits in every other way may have a collector that’s turned the wrong way, throwing a monkey wrench in the works. Swap headers address this collector conundrum with properly pointed outlets to work with the individual engine/chassis swap combination. In some cases, a block-hugging cast manifold is the only way to go. Just know aftermarket cast manifolds are designed to flow better than the stock offering.
The headers you choose should have solid, thick flanges and stout welds to resist distortion and exhausts leaks. Today’s modern EFI engines don’t like leaks and may throw check engine lights in protest. You also want a header flange-to-pipe relationship that doesn’t interfere with spark plug, plug wire, and bolt access. Emissions are another prime concern. In this respect, shorty headers are the go-to because their design promotes quick catalytic converter light-off and allow the installation of oxygen sensors closer to the exhaust ports where they can function properly. This makes them 50-state legal for most applications – but check for applicable laws that apply in your state.
Headers are one of those muti-faceted mods that hit all the senses – they look great under the hood, throw you back in the seat when you jump on the throttle, and captivate your ears with that throaty rumble we all lust after. Understanding the different designs of headers will help you make informed purchasing decisions and get the most bang for your performance buck.
