We've all seen them: those gigantic exhaust tips and systems flooding black smoke on the highway. They roar through the streets and, to the untrained eye, look like nothing more than some diesel driver's vanity hard at work. But is there something more to the shiny silver systems that seem to be a staple addition to everyone's performance checklist? Surprisingly, there are a great number of reasons why a new exhaust system may be more than just an aesthetic addition to your daily driver. In fact, it could be one of the most important things you ever put on that power-hungry diesel of yours.
When a manufacturer builds a vehicle, it uses cost effective and, at times, the cheapest stock parts that can be found. For some owners that's fine, but diesel drivers are never happy with plain-looking, mediocre-performing stock pickups. It's a good thing the manufacturers leave so much room for improvement.
At times in our industry, a lot of owners’ install lists start with a new turbo, tires and without a doubt, a performance exhaust system. But it seems like there aren't too many people who can describe why a new exhaust setup is so essential to the build. When the factory assembles the exhaust in any diesel, they tend to stay on the economical side and build the system with cheaper parts. These parts suit the stock pickup just fine, but lack in a lot of different ways.
Restriction
First off, the smaller, narrower construction of the stock exhaust restricts the free flow of exhaust gasses leaving the truck. This in itself may not seem like a problem, but in actuality, it restricts just about everything on the truck. A truck can be looked at like a person. It needs to inhale and exhale freely and the modestly-sized stock exhaust system keeps the truck from exhaling completely. Here are some basic differences between a stock and performance system.
In a stock exhaust system, hot exhaust gasses are given less room to expand and ultimately cool down. This keeps EGTs higher in trucks with performance parts installed. Cooler, richer air is an essential catalyst for anyone looking to get more performance out of his truck. The stock system will control exhaust temperatures just fine when the truck is completely stock, but if there are any performance modifications added to the truck, EGTs are undoubtedly going to rise. The performance exhaust, notably larger than stock, allows the exhaust gasses a wider avenue to exit through, thus allowing them to expand and cool, keeping temperatures lower.
Combustion
Another thing to consider about adding a larger exhaust system to your diesel has to do with the rate that the engine will be able to combust fuel. Because exhaust gasses freely disperse through a performance exhaust system, spent fuel is "exhaled" faster, meaning more fuel and air can be burned, which equals better performance. An upgraded turbo is a hot item for installation on diesels, but without proper exhaust, the turbo will not be able to operate to its full potential. Remember: if your truck is breathing in more air at a faster rate, it'll have to exhale a comparable amount of exhaust in order for that beloved daily driver to run like a performance pickup.
Size Matters
Another important detail to remember is what size exhaust system should be installed. The phrase "go big or go home" gets thrown around all the time, but shouldn't be the mindset when you're looking to upgrade your exhaust. It all depends on what kind of performance you intend on putting into your truck at the end of the day. A bigger turbo and a serious air intake overhaul certainly warrants a sizable exhaust system, but throwing a 55-gallon drum stack in your bed not only looks ridiculous, but can draw back the performance just like a pipe too small will.
Every part of your truck is about rhythm. Your cam and crank need perfect timing to run clean and smooth and your intake and exhaust system need the same sort of relationship. Here's the point: just because that 6-inch turbo-back looks shiny and menacing, if you're not feeding your truck with the air it needs, you're actually hurting performance, not helping it.
Sometimes being modest is the best thing to do. If a solid 4-inch system could comfortably handle all the power that you have to throw at it, it'll also give you the best power gains on the truck. If you intend on putting in a triple turbo system and about $70,000 worth of drag racing performance, it would probably be okay to get a bigger exhaust, not to mention a roll cage.
Be Materialistic
A lot of times, people see those shiny pipes as a bit too much, but that couldn't be further from the truth. The stock exhaust will, over time and sooner than you think, rust out and cause all sorts of issues. Aftermarket exhaust manufacturers select premium stainless-steel during construction, which will stand the test of time and could possibly outlive the truck all together. There's something to be said about the beauty of a brand new exhaust system, but the durability and resilience of that new system should say it all.
Exhaust systems are usually one of the first things on the list to buy because they're relatively affordable, but they can provide a lot of help to the performance of your diesel if you go about it the right way. Choosing the correct performance system will not only look great, but give you the best power results and keep your diesel running the way it was meant to.