Ever stop to think how rambo overcame all his enemies? He didn't just carry a big gun-he also had a really sharp aim and a lethal strategy. The same thing applies in getting the most firepower out of your diesel engine. It isn't as simple as throwing on a huge turbo. Sure, it can produce monstrous power once it spools up, but what about getting off the line? And don't forget all those adjustments to the fuel delivery system required to keep up with the increased airflow, while making sure you're not just blowing a lot of black smoke. Keeping that in mind, what follows is the latest on a new weapon for the arsenal of diesel enthusiasts: the ATS Multi Stage Turbo (MST).
Twin Turbos, With A TwistWhat sets the MST apart is a valve design that directs exhaust gases to two different sized volutes in the turbo's exhaust housing. The gases enter into the turbine section and are directed to the first volute section of the turbine housing. The first volute is small, which is said to cause the exhaust energy to rapidly accelerate the turbine wheel, producing immediate boost much like a very small turbocharger will do in a large displacement engine.
As the engine produces more exhaust flow, the exhaust energy is diverted by a valve in the turbine housing to the second stage's larger volute. The large one-piece diverter valve regulates exhaust drive pressure based on engine speed and load, delivering both midrange torque and top-end performance. In other words, you get your cake and eat it too with that big turbo performance and small turbo spool-up.
Beta Test Bed In BlackSteve Benson's '05 Dodge Ram 2500 4x4 served as the Beta version of this innovative two-stage turbocharger, being the first truck armed with a production version of the MST. We should note that Steve has one big tactical advantage-he's the research and development turbo engineer behind ATS Diesel Performance. In other words, he knows his way around turbine and compressor wheels, and how to draw up a battle plan for performance.
Steve's truck began life with some chassis mods: a 4-inch Tuff Country lift kit and 20-inch rims wrapped with 37-inch Toyo tires. To make it easier to climb into the raised cockpit, he added a set of AMP retractable running boards. The lift also shows off the ATS differential cover that holds a higher volume (2.5 quarts more) of gear oil for better lubrication and cooler running.
With this basic preparation behind him, Steve was ready to arm his war wagon, starting with an expandable computer control. "The ATS E-Power Tuner was the first thing that I installed on the truck after all of the accessories were bolted on," he points out. "The E-Power was very easy to install and came with a low power setting when the stock turbo was still on the truck."
ATS has been working on its Multi Stage Turbo (MST) technology for years. The MST acts like a variable geometry turbo to provide quick spool-up without overspeeding the turbo. A one-piece valve (seen in red) sends exhaust drive pressure to the small port at low speeds. As engine speed and load increase, the valve diverts exhaust gases to the larger port to reduce back pressure and to continue to provide boost to the engine.
Why was this initial step so important? "After the addition of the turbo upgrade," he explains, "the E-power made it very easy to change the power setting of the computer, allowing for all the extra fuel to be injected into the engine."
Fuel To Feed The FireSteve also threw on bigger ATS Stage One injectors (good for about 90 hp). These not only have 10 holes, instead of six, to deliver more fuel, but also use smaller orifices for better atomization. This step is almost as simple as switching the setting on an M-16 from semi- to full-automatic, but you gotta make sure you have plenty of extra bullets as well. In diesel terms, that means supplying way more fuel, and that's where the dual CP3 injection pumps come in. For those who are not familiar with this system, we should provide a bit of background information.
It's a well-known fact that, unlike its gasoline brethren, a diesel engine throttles on fuel instead of air. So it comes as no surprise that when you're upgrading the power output, you need to feed it more fuel.