Backpressure is bad! No, not the pain you feel in the lower part of your body each time you leave the pump, but the kind that restricts your diesel's exhaust. Keeping your exhaust free-flowing is crucial to maximizing the performance of your turbodiesel engine. So what makes the exhaust so important? To answer this question, first take a look at your engine's turbocharger. Even though a turbocharger essentially is an exhaust restrictor, it uses the exhaust to create more power. How?
A turbocharger works by taking the heat and pressure exiting the engine's exhaust valves and dumping it into the turbine housing to propel the turbine wheel. Using the kinetic energy, the spinning turbine wheel rotates an opposing compressor wheel through a shaft that connects the two together (think water wheel). This allows the turbo to pack more air more densely into your engine, thus creating more power.
So what does all this have to do with exhaust? It's simple. The faster the turbine wheel can accelerate, the faster your turbo will spool up and get your truck moving. If you create a larger opening for the hot air to escape after the turbo, it can work with less restriction and with greater efficiency, not only improving your off-the-line torque, but lowering EGTs (exhaust gas temperatures). By lowering the EGTs you invariably prolong your turbo's life and decrease the probability of mechanical failure through heat. Though it's common to see exhaust manifold temps in the 600-800 degree F range, loading up your truck with aftermarket power modifications can send your EGTs peaking past the 1,300 degree mark, and when run consistently over this number, serious mechanical damage can occur.
The reality is, if you want to turn up your diesel's power safely-without breaking the bank-an exhaust system and pyrometer is money well spent. Whether you're looking at set of 6-inch stacks or a 4-inch turbo-back system, we suggest doing some research and fitting the best exhaust diameter to match your truck's power and turbo needs. So until next time, keep those diesel engines spooled up and roaring down the trail!
Flow And Go
Though there are a wide variety of aftermarket turbochargers and exhaust components, figuring out what's best for your diesel often times boils down to personal preference. Although a turbo swap might be out of the question for many, something as simple as plugging in a performance downloader can alter your truck's boost and EGT levels, so you will need to modify your exhaust accordingly. And if a new turbo looks like something that might be in your future, a good rule to follow is the larger the turbo, the bigger the exhaust.
Downpipes are one of the most important elements of your diesel's exhaust system. Since it's the closest to your turbo, it's the first line of defense to help get the hot air out faster. | 
Monitoring your engine's exhaust gas temperatures is extremely important so you know if you are reaching into damaging ranges. Average driving temps usually run between 600 and 800 degrees Fahrenheit (exhaust manifold temps before turbo), and can safely peak into the 1,200 degree range when towing or under heavy acceleration. A simple and inexpensive EGT gauge can save you from some serious wrench time under the hood, and is as easy as drilling a hole and dropping in a pyrometer. | 
Though most aftermarket exhaust systems slide and clamp together, it may be necessary to get your truck in the air to have enough room to squeeze on the new piping. Our friends at Diesel Tech were kind enough to let us use their drive-on lift for a little while, so we tossed on a new 5-inch muffler from Hushpower. Be sure to check us out on the Web at www.4wheeloffroad.com for an exclusive online review of the manufacturer's latest muffler. |