Liviu Marcus
Selecting exhaust headers for your vehicle is all about making decisions. You will have to decide which style exhaust header is best for your combination; long tube, shorty style, mid length or front exit style. You will have to decide on the primary tube diameter. Most of these decisions will depend on what you are going to do with your vehicle. Is it a street car? Is it a race car? Is it a street/strip car? So, before you make a decision about your exhaust headers, you are going to need to decide what you want to do, or are doing, with your vehicle.
Now I will explain what to look for when shopping for an exhaust exhaust header. I’ll pull out all the little details that add strength, reliability, horsepower, and even style so you can know you’re getting the best product that will last—not rust, warp, or leak.
Don’t miss the last two on this list! I’m going to explain the performance differences between a Tri-Y exhaust header and a four-into-one exhaust header so you can decide which one is best for your project. And finally, I’ll answer that age-old question of whether or not you should ceramic coat your exhaust headers.
Let’s start with number one.
Table of Contents
1) Flange Thickness
You want to go with at least a 3/8 of an inch thick flange. 3/8 of an inch is the bare minimum—go a little bit thicker if you can. Yes, only a few millimeters will help. This will prevent your exhaust header from warping.
If your exhaust header warps, it’s going to leak and sound terrible. Severely warped exhaust headers can even break studs and bolts. And getting a broken stud or bolt out of a cylinder head is no fun at all.
Also, make sure that the exhaust header you buy has had the mating surface sanded flat so that it will properly seal up against the cylinder head.
Exhaust Short Header for 2009-2018 Hemi 5.7L Dodge Ram 1500 Manifold (Silver Polished)
2) Welded Ports
Many exhaust header ports are only welded on the inside of the tube and flange. They should also be welded on the outside too—this is another sign of a good exhaust header. Doing so helps increase the exhaust header rigidity and better supports the weight of the exhaust header in the exhaust system.
Flanges will sometimes even be welded with a really cool silicone braise that gives it a super cool look, as you can see there on the left. Some companies will cheap out and just do a stitch weld. That’s better but not ideal. It makes you wonder how many customers had broken exhaust headers before they started to do that.
3) Hand TIG Welds
TIG welding is a high-quality weld that looks a lot nicer than MIG. These days, most of the welds you’ll find on exhaust headers are pretty good. But still, if you see really nice welds, it’s just a sign of a super high-quality brand that cares about even these little small details.
Of course, pretty welds do not make more horsepower. It just gives you a small clue that this may be a quality exhaust header. And it looks really nice.
4) Equal Length
Equal-length exhaust headers—this is one you’ve probably heard of, but you may not know why it’s good. The exhaust valves of the engine are firing at different times as the engine spins around. This creates waves of exhaust passing through the tubing of the exhaust header.
Look at the exhaust header above. As the waves each flow through the exhaust header tube of the same length, the pulses are spaced out evenly when they reach the collector.
Here you can see an unequal-length exhaust header. The top tubes are shorter than the bottom ones. This creates a possible situation where one or more of the exhaust pulse waves is hitting the collector at the same time. This creates a bottleneck and turbulence inside the collector, which slows everything down and causes a loss of horsepower.
Equal-length exhaust headers also have more of a scavenging effect. As the pulses in one tube flow out, they create a vacuum on the other tubes in the collector, actually pulling the exhaust gases out of the other tubes. This scavenging effect makes the whole thing more efficient.
Now, at high RPM, this horsepower loss can be substantial. Hooker exhaust headers actually claims up to 50 horsepower can be lost in race engines at high RPM, although I’m guessing for most applications it’s much, much less than that, especially on the street.
5) Cone Shaped Collector
Deep inside the collector of the exhaust header, you should find a cone-shaped connector welded to the pipes. The only way you can see it is to look into the collector, and it should look like the image on the left. This cone shape helps the air exit and also pulls air from the surrounding pipes.
During manufacturing, it looks like this. Call it a cone, spear, or pyramid—whatever you prefer. The purpose of this pyramid is to control the exhaust gases so they do not re-enter the primary tube and travel backward toward the engine. This is a small feature that reflects quality and attention to detail. While it’s not a huge power gainer, every little bit helps in making more power and increasing efficiency.
6) Stainless Steel
You want stainless steel exhaust headers, but did you know there are over 150 grades of stainless steel? Luckily, exhaust headers are almost always 304 or 409. A quick note: if you can afford it, avoid mild steel exhaust headers—they will rust quickly. Mild steel exhaust headers often come with a cheap water-based coating to protect them during storage and shipping. That coating must be stripped or sanded off and repainted before installation.
The preferred option for stainless steel exhaust headers is 304 stainless, and here’s why: chromium and nickel content. In 409 stainless, the chromium content is half that of 304, and 304 has 10 times the nickel content of 409. A magnet will stick to 409 stainless exhaust headers, and the areas where it sticks will rust. However, a magnet will not stick to 304 stainless exhaust headers.
409 will develop surface rust but won’t deteriorate or flake off like mild steel. It has more iron, so it rusts more. On the other hand, 304 corrodes slightly, turning into a cool goldish color over time.
Exhaust Header for 2008-2017 Subaru Impreza WRX/STI EJ25 (Racing styles)
7) Tri-Y vs. 4-into-1
This is the age-old debate. The commonly accepted theory is that a 4-into-1 exhaust header offers more top-end power, while a Tri-Y exhaust header is designed to bolster mid-range torque.
The idea behind a Tri-Y exhaust header is that having just two tubes allows the exhaust from one tube to rush past the other, scavenging air out of that second tube. If you plan to tow or cruise around town, consider a Tri-Y exhaust header. For maximum high-RPM power, go with a 4-into-1. While many factors affect a exhaust header’s performance, this gives you an idea of what to expect when choosing between these styles.
8) Ceramic Coating
Ceramic coating or not? That’s the question. In my opinion, ceramic coating doesn’t look as nice as raw 304 stainless steel, but it certainly looks better than painted exhaust headers, especially after miles of use. It’s also more durable than paint.
If engine compartment heat is a big issue, ceramic coating could be a great option, especially for turbocharged cars that generate a lot of heat. Ceramic coating retains heat within the exhaust headers, which increases exhaust gas velocity, improves scavenging, and potentially boosts power. It also lowers engine compartment temperatures, reducing intake temperatures.
I recommend getting 304 stainless steel exhaust headers and leaving them as is. They look great, even as they corrode.
If you want to learn more, check out DynovoxParts.com and good luck with your project!
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