Overcoming the reputation that diesel engines had been known for was a consideration when Chrysler Corporation made the decision to install the Cummins Turbo Diesel in their trucks starting in 1989. What may have appeared to be a marketing ploy to renew interest in their aging truck line, the Dodge Boys knew that they had stumbled across something big. The Cummins was, after all, one of the most widely-used diesel power plants in the world, finding its way in everything from light-duty over-the-road trucks to fire engines, motor homes, and even ocean going boats. And when the Dodge truck was introduced in 1994 with its muscular semi-truck looks, the Cummins Turbo Diesel seemed like a natural accoutrement. The public caught on, and ever since then, those in the know (and with sufficient cash to pop for the Cummins option) realize that the ultimate towing vehicle available to the general public is the Dodge truck with the Cummins Turbo Diesel engine, automatic or manual.
As popular as these trucks have become, however, there are surprisingly few owners that know (or even care about) how the diesel engine works, or how much potential lay within its oily cylinders. Perhaps its because in as-delivered form theyre powerful enough for most people. Maybe its because theyre so reliable, most people simply take them for granted. But there is a small group-or perhaps, more accurately, a cult-of enthusiasts out there who not only understand and care about the Cummins Turbo Diesel, they revere them. If youre one of those people, then Ted Jannetty has got a deal for you.
Proprietor of Jannetty Racing Enterprises in Waterbury, Connecticut, Ted specializes in the sales and installation of performance automotive accessories, and the vehicle of his choice is a Cummins-powered Dodge truck. As an enthusiast, Ted was interested in extracting more power from his truck, and began researching what is commonly done to make the diesel really haul.
The fruit of his efforts is what Ted calls a "Diesel Power Kit." It consists of an injection pump cam plate, a bleed orifice fitting and a K&N air filter-the only items necessary to make truly big power with the Cummins.
How big ? It depends on the intended application-but the Stage 1 Diesel Power Kit produces an additional 40 horsepower and 180 ft-lb of torque-and then there are three more stages! The second two stages require consultation with Jannetty to prevent you from shredding the driveline into tiny bits.
Unlike a gasoline engine that requires extensive internal modification to produce serious power, a diesel needs only more fuel, and air in the form of turbo boost. "A diesel is basically like a furnace," says Jannetty. "The more fuel you give it, the hotter it gets, which is the exact opposite of a gasoline engine. To keep exhaust temperatures within a safe limit, you pressurize the engine with compressed air from the turbo, which is driven by the heat of the exhaust."
The Cummins Turbo Diesel, like many other diesel engines, uses the Bosch P7100 in-line injection pump to supply the engine with fuel. Inside of the pumps Air Fuel Control (AFC) housing is what is known as a cam plate. As engine rpm rises, a fuel rack within the pump climbs the profile of the cam plate.
By changing the profile, Jannetty effectively changes the fuel curve of the engine. Next a small, barbed fitting at the rear of the AFC housing (or on the compressor housing of the turbo on some engines) is replaced with a barbed fitting featuring a tiny orfice that bleeds off the boost pressure signal to the waste gate. Keeping it closed longer allows for more turbo boost. A small set screw regulates the amount of bleed; it is pre-set by Jannetty for the application and then locked in place.
If more fuel is what contributes to added power, then why not change the fuel injectors ? Jannetty maintains that this is another approach to making more power with the diesel, and in fact, bigger injectors and a cam plate is how Jannetty makes huge power with the high-level kits. But to produce Stage 1 and II power levels, the injector plate is a simpler and more cost effective approach.
To see just how effective the Diesel Performance Kit is, we recently visited Duttweiler Performance in Saticoy, Califorrnia. Owner Kenny Duttweiler is one of the foremost authorities on turbo charging and fuel injection in the country, and recently he began experimenting with various modifications on his own 97 Dodge. Among these were a Stage II plate, a Stage II plate and larger injectors, a Stage III plate, and a torque converter form Pro Torque (see sidebar "Conversion Factor"). On the day we stopped by, shop foreman Chris Raschke was installing a Stage II Diesel Performance Kit as well as a set of injectors, so we had the opportunity to photograph the installation of both.
During the same week, Sam Davis of Gold Coast Coatings (a Camarillo, California, shop that specializes in high-temperature ceramic and powder coatings) was having a Pro Torque torque converter installed in his dually at Germanson Automotive and Performance in Oxnard, California, under advisement from Duttweiler. This was fortuitous indeed, because owner John Germanson is a fuel injection and turbo / supercharging specialist in his own right, and just so happens to have a 500hp, fully-computerized in ground Mustang chassis dyno in his 6,000 square-foot shop, This gave us the opportunity to photograph the installation of the torque converter and test the effectiveness of the Jannetty components that were installed at Duttweilers.
As you will see, installation of the above components isnt very difficult, and the results are definitely worthwhile.
Putting an engine in front of a transmission that was never really designed for the application can have its consequences-especially reliability problems. Through the TorqueFlite-based transmission in the auto-equipped diesel Dodges is a very tough unit, the factory hedged their bet somewhat by fitting it with a loose torque converter. By sacrificing some of the input torque to the transmission through built-in slippage, the trannys innards are spared some of the abuse that 400-plus lb-ft of torque (in stock form) can dish out Undoubtedly, the factory is trying to protect itself from excessive warrantee claims from abusive bone-head drivers, but to the rest of us, it simply means that all of that glorious torque isnt getting to the rear wheels where we want it.
"The factory torque converter is like a sponge," commented Joe Rivera, Jr. of Pro Torque torque converters in Bohemis, New York "It soaks up all of the input torque from the engine. So when you bump up the power, it never really gets to the rear wheels." To solve the problem, Pro Torque lowers the stall speed from the factory 2,000-2,500 rpm to 1,600-1,900 rpm, and increases its torque multiplication and overall efficiency through a proprietary (read: secret) process. The results is improved fuel economy, reduced transmission temperature (through reduced converter slippage), increased low-end power and top-end acceleration. To ensure their product will last behind some seriously-tweaked diesels, Pro Torque installs Torrington bearings on both stator and pump surfaces (the factory converter only uses a bearing on the pump surface) and the turbine assembly is furnace brazed. In addition, the Pro Torque converter uses a ceramic-impregnated lock-up clutch that has 15-percent ore surface area than the stock clutch.
Though we didnt have time enough to test Pro Torques claims for ourselves, Sam Davis reports that the drivability of his truck has improved by 40 percent, while Duttweiler claims that a Pro Torque converter is an absolute must, especially if the engine gas been, or will be modified. Sounds good to us.