Replacing your classic car’s exhaust manifold with aftermarket car headers can offer a performance boost, but whether you are going to opt for long tube or shorty headers depends primarily on what you are focusing on with your build and what other options you have already installed.
Understanding how these car header’s function and how their differences affect the horsepower and torque gains they can offer will allow you to select the best set of headers for you.
Like about any integral performance part of your engine, the exhaust system is often over simplified as we previously discussed in Exhaust Diameter Size Matters.
To help answer this, we need to start where your exhaust starts: the headers.
Exhaust Headers Basics
The first, and most basic job of your exhaust manifold/headers is to funnel exhaust gases away from the engine bay to the rest of your exhaust system to vent those gases somewhere out of the way. While they are doing that, their second job is to get this done in the most efficient way possible in terms power and fuel economy. There are packaging concerns as well, you must fit all this piping somehow, but for the sake of this article we will not worry about that.
Exhaust Headers vs Exhaust Manifold – What is the difference?
Why is it that people usually refer to the stock equipment as an exhaust manifold and refer to the aftermarket parts as car headers? Well technically speaking they are both manifolds, but the basic distinction between them is in how they are constructed. An exhaust manifold is a single large piece of cast iron with the separate tunnels for each cylinder’s exhaust gases to flow through before combining into one larger pipe at the collector.
Meanwhile exhaust headers are typically made from individual tubes for each cylinder that are bent to shape and welded into place, also combining down into a single pipe, flowing out into the catalytic converter (typically) and then the rest of the exhaust system.
Pros and Cons of Car Headers Over Manifolds
Pros:
- The smooth walls of the header piping are better for flow than the rough walled castings of the headers.
- Manufacturers have more freedom of pipe length and routing with more compact headers (more on that later).
- Headers are lighter weight for the same size.
Cons:
- The thick walls of cast iron exhaust manifolds insulate heat away from the rest of the engine bay better than thin walled, steel headers (generally).
- Headers are often more expensive to manufacture.
So, you can see from the above why it makes more sense for most manufacturers to equip their engines with cast iron manifolds over car headers — especially in applications where there is not as much of a need for maximizing performance. Manifolds flow well enough, keep under-hood temperatures down, and are cheaper to make on average. It is usually only once you get to more performance-oriented applications that you will start to see headers on a vehicle from the factory.
Now that we got all that out of the way, let us get to the question that landed you here:
Why Car Headers?
Why Headers? Headers (also called “tubular manifolds” or “extractor manifolds”) are just another element of your exhaust system that helps your car “breathe” — intake air and let out exhaust. They do this by limiting the amount of backpressure that your exhaust has to overcome to escape, which can be a real power killer for your engine. The many tubes that make up car headers direct each of your engine cylinders’ exhaust to a main collector pipe at different times to keep the whole system free of backpressure and running smoothly. And that is why they are so important for improving the performance of your vehicle.
But again, we are faced with the issue of shorty vs long tube headers, because they have unique strengths and drawbacks that could make or break your performance on the track. Let us dig into the pros and cons.
What Is Scavenging, and How Do Equal Length Headers Help?
Scavenging can be thought of as the opposite of backpressure. With efficient exhaust flow, the outgoing gases will create a vacuum behind the pulse. As the valves are opening between cylinder strokes, there is a sweet spot where the intake and exhaust valves are at least partially open at the same time. During this brief moment, that vacuum will actively pull in fresh air through the intake valves resulting in an effect not dissimilar to what you would get from mild forced induction.
More air in the cylinder means more power, and more power means more smiles. Who does not like smiles?
Two things happen once you exhaust valves open; first is a high-pressure shock wave caused by the rapid expansion of hot exhaust gasses as they exit the valve, traveling at the speed of sound (about 767 miles an hour). Following behind that is the actual burst of exhaust gases, which will ideally be unimpeded in exiting the headers through the collector into the rest of the exhaust system.
Once this shockwave reaches the end of the pipe and equalizes to atmospheric pressure, a low-pressure wave is sent back up the tube to the cylinders to pull that air through the cylinder.
Where equal length headers come into play to help here, is by ensuring that each the tube from the cylinder head to the collector is the same length, those exhaust pulses have the same distance to travel to get there. That way, there is always a clear path for the exiting exhaust to free up as much back pressure as possible for the next pulse coming back down that line, ensuring as close to ideal conditions for scavenging as possible.
Short Tube Headers
This header style is a shorty you can be proud of. Shorty headers give your exhaust manifolds free flowing piping that will improve the performance of even a naturally aspirated motor. But short tube headers really shine when they are used in conjunction with a turbocharger — their more compact size fits nicely in the engine bay right alongside your turbo flange and piping. Their size also makes them easy to install. Short tube headers are ideal for vehicles in the idle to mid-RPM range, so if you are looking for more power in your daily ride or work pickup, they might be the option for you.
Another big benefit of shorty headers? They are legal in all fifty states. Playing around with your exhaust system is a big no-no in states that require emissions checks on vehicles, so unless you live in Alaska, Arkansas, Iowa, Minnesota, Montana, South Carolina or South Dakota, your souped-up ride might not be street legal with long tube headers. Also, long tube headers are loud, so neighbors who do not appreciate the fine art of burning rubber might file a complaint.
As for drawbacks? Shorty headers are not as loud as long tube headers, although they will have better sound than your stock manifold. You can choose unequal length headers for better sound, but equal length is the way to go for consistent gains in performance. Shorty headers also are not used for high RPM situations, especially when used with a turbocharger — all those rotations can hurt your turbo!
Pros Of Shorty Headers:
- Legal in all fifty states
- Easy to install
- Great for turbo applications
- Better sound than stock exhaust
Cons Of Shorty Headers:
- Not as loud as long tube headers
- Not great for high RPMs
Long Tube Headers
You have gotten a little preview of long tube headers in the previous section, but now we are going to dig in deeper. Long tube headers work with naturally aspirated and supercharged applications, so you know what that means: long tube headers are unquestionably the option you want to go with if you want to max out your RPMs and tear up the track. They also have an awesome, roaring sound that’ll make it hard to resist putting the petal to the metal whenever you get in the driver’s seat.
So, aside from not being compatible with turbochargers, why wouldn’t you want long tube headers on your pony? Well, as we mentioned above, long tube headers do not fly in all fifty states. Installing them means either relocating or removing your catalytic converter altogether, so your car will not be able to pass an emissions test if you live in a state that requires them. Because of their size, long tube headers are also quite a bit more complicated to install than shorty headers, so you will need professional help if you are not experienced or equipped enough for this kind of upgrade. And, of course, there is the issue of sound.
Pros Of Long Tube Headers:
- Major performance boosts
- Awesome, loud sound
- Great for high RPM applications
- Can be used with stock or supercharged exhaust
Cons Of Shorty Headers:
- Not legal in all fifty states
- Not compatible with turbocharged engines/exhaust
- Tough to install
- Could make the neighbors angry
Long Tube vs Shorty Headers – Which is Better?
Well… that depends.
First, if you are running a turbocharged car, long tube headers are not usually feasible or practical, so these cars will usually have shorty headers that feed right into the hot-side inlet of the turbo. Otherwise, long-tube headers are the best for reducing back pressure as much as possible, and therefore the best for scavenging — this is despite the fact that they actually technically flow less than shorty headers generally do, but after the section above, we have a good understanding of why that is.
Another advantage with long-tube headers is that they not only give solid peak power numbers but help to raise horsepower and torque in the low and mid-range of the RPM band, giving you more useable power down where you usually need it. This makes for a more fun drive day to day, as you are rarely able to enjoy wide-open throttle out to redline out on the street.
The disadvantage comes in the form of packaging. Some cars are worse than others, but it can be difficult to route that big cluster of tubes out of the way of motor mounts, the firewall, the transmission, and still have ground clearance for them afterwards.
Meanwhile, not only do short-tube headers make packaging easier, they also are designed to bolt right up with your stock exhaust, allowing you to easily bolt in a set of headers without having to worry about custom fabrication, or having to move stock emissions equipment like your catalytic converter(s), which can get legally messy in some states.
