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Headers have been a mainstay in performance upgrades since the earliest days of hot-rodding. With inherent benefits like a richer, burlier exhaust note and the potential for significant increases in engine output, it’s not hard to see why they continue to be a go-to modification for gearheads across the automotive spectrum.
“Headers tend to be more tuned for the engine and application than an exhaust manifold would be,” says Mark Emerson of Holley Performance. “That tuning helps evacuate the exhaust gases at a faster pace and maintain the proper velocity for the exhaust pulses. By timing it so they hit the collector together, it maximizes the scavenging effect, which helps to get all of those exhaust gases out of the combustion chamber. At the same time, it also helps pull in some of the intake charge, which further improves the efficiency of the engine.”
Firing order, camshaft profiles, and other external variables play into this tuning as well. But as he points out, there is one particular circumstance that usually prevents OEMs from outfitting their vehicles with headers from the factory. “Packaging is the big factor. Headers generally take up more space than exhaust manifolds do, which can make manufacturing difficult.” Fortunately for us, we don’t have to worry about the constraints of mass production. We do, however, have some different options when it comes to header materials and coatings, so we sat down with Emerson to get the details on what’s available and what makes the most sense for a given application.
Generally speaking, headers are made from either mild steel or stainless steel. Mild steel is the more budget-friendly option of the two, but stepping up to stainless offers some important benefits that shouldn’t be ignored.
“304 and 409 are the most common options when it comes to stainless steel,” he says. “304 is going to be the more durable of the two, as far as corrosion resistance goes. While 409 can develop a layer of surface rust over time, depending on the application and use-case, it also has generally good corrosion resistance, too. And because of that, if you’re going to use a ceramic coating on the header anyway, opting for 409 stainless can be a viable way to save some money without sacrificing durability.”
Beyond its corrosion resistance, stainless steel also offers some aesthetic benefits. “There’s a visual appeal to it, too – especially 304 stainless. You can polish it up and get it to look really nice.”
However, it’s important to know that some maintenance is involved if you want those stainless headers to stay looking their best. “Applying metal polish on occasion will certainly help, but you also need to keep in mind that if the engine is running too lean, it can cause the headers to turn sort of a yellow color. The change generally isn’t as dramatic as it would be with a chrome plated header, but it’s something you should watch out for.”
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Although it doesn’t yield a performance benefit, chrome plated headers can really make the engine bay of a show car pop. “This is a visual thing more than anything else,” Emerson says. “If you’re building something that’s going to be shown, or only driven occasionally, chrome plating can add some under-hood visual appeal. Sometimes you’ll also see this on race cars for that same reason.”
But as Emerson mentioned earlier, chrome plated headers do require regular upkeep if you want them to stay looking their best. “They have to be cleaned regularly, and if the engine isn’t tuned right, they’ll start to turn blue. And once they turn blue, they’re going to stay that way. Some folks like that look, though.”
High-temperature paint is a cost-effective way to spruce up your headers without breaking the bank. This is generally going to be the least expensive way to add an external treatment to your headers, and Emerson says that it can be a solid option for a daily-driven vehicle.
“A high-heat engine paint can give headers a nicer look, and it also gives you a lot of different options for colors. If you’re wrenching in the engine bay regularly, the potential for scratches or chips does increase, but the nice thing is that you can just touch up the paint cheaply and easily.” He says that a good high-temperature paint coating should last for years, though heat cycles will start to dull the brilliance of the hue over time.
While this header treatment provides some visual benefits as well, ceramic coating offers advantages that go beyond aesthetics.“If it’s within your budget, this is your best option,” Emerson says. “You can get ceramic coatings in different colors like black, silver ceramic, or titanium, and that gives the headers a nice, uniform appearance. And ceramic coating is also much more durable than high-temperature paint. But the biggest advance of ceramic coating – especially if that coating is applied inside and outside – is that you can create a really good thermal barrier. That thermal barrier helps to keep more of the heat in the pipes, which in turn helps maintain pulse velocity. And by keeping more heat in the headers, you’re reducing under-hood temperatures, too.”
As a result, that thermal barrier can also yield some performance improvements. “In an exhaust system, the more heat you can retain inside the pipe, the faster the exhaust pulse can travel,” he explains. “And reducing those under-hood temperatures is likely to provide a measurable improvement in intake temperatures.”
Emerson also notes that while ceramic coating does create an effective thermal barrier between the header and the outside world, it’s probably not a good idea to leave wires or other components resting on ceramic-coated headers. They’ll still cook on there, albeit at a slower pace. “You can get away with running certain things a bit closer to the headers, but generally speaking, you still want to keep everything clear of the headers – especially fuel lines and things like that.”
As with many performance upgrades, determining the best header finish for your particular application starts with an assessment of your budget and an honest look at how the vehicle is going to be used.
“If it’s a demolition derby car, you might not want to spring for stainless steel headers with a ceramic coating,” Emerson quips. “That person will probably want a mild steel header and then they can just paint them. But if it’s a situation where you’ve got limited space in the engine bay, you’ll definitely want to try to get ceramic coating because that thermal barrier can provide significant benefits in that use-case.”
He also tells us that springing for stainless steel is a good idea even with a ceramic coated header. “This is especially true if it’s not coated on the inside of the header. Condensation can still build up in there even if you have a ceramic coating on the outside. And if that happens, corrosion can set in from the inside if the header is made from mild steel. This tends to be more of a concern for vehicles that aren’t driven regularly and sit for extended periods of time, though.”
For those who have additional questions about what header finish makes the most sense for their use-case, Emerson suggests checking out resources like the 304 vs 409 stainless steel comparison video below, or simply giving Holley’s main tech line a buzz to speak to an exhaust expert.
“This is a situation where the FAQ page might be a little too broad to cover all the bases. Calling in allows our techs to ask questions about your specific application, which will help them zero in on what makes the most sense for your project.”
Call Holley now to get the right headers for your vehicle: 1-866-464-6553
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