HistoryElectronic diesel engine tuning probably dates back to the first electronically controlled diesel car engine made, the 1986 BMW 524td. One of the first companies to make diesel tuner devices for this car and others was Superchips. By the time performance enthusiasts in the United States had begun to realize the performance potential of diesel, Superchips had already been making electronic re-tuning chips for over 15 years. Unsurprisingly, it cornered the market on tuners for a number of years, but quickly began to face a great deal of competition.
Basic FunctionA diesel tuner controls two things primarily: fuel delivery and turbo boost (if electronically controlled.) Since compression ignition engines make power linearly to the amount of fuel they ingest, simply increasing the amount injected can increase power in most applications. However, most tuners recalibrate the stock boost controller to tap more of the turbo's potential. When one combines an increase in boost pressure with an increase in fuel, the inevitable result is more power.
Tuner BenefitsIn a word: power. In two words: power and versatility. The main differentiating factor between diesel and gas tuners is their ability to wildly vary the amount of available power at the push of a button. Unlike stock cars, which may stand to gain as much as 40 horsepower in some applications, it's not uncommon for many engines to see a 100+ horsepower and 250+ pound-feet torque increase with no more than a tuner. Not only does this make for a faster truck, but may actually increase drive-line durability by allowing the transmission to run in a higher gear and produce less heat when towing.
DrawbacksThere's no such thing as a free lunch with anything automotive, and the same holds true here. Traditionally, diesel tuners have caused premature turbo failure and higher emissions, since they tend to send still burning fuel through the turbines. However, modern tuners like Banks have worked many of the bugs out of their electronic controls, meaning that hot diesel truck owners must no longer tolerate the noxious clouds of blue-black smoke that plagued enthusiasts of the past, or the engine failure concordant with them.
Other ConsiderationsThough the stock turbo has a great deal of untapped potential, the wise owner would consider replacing it with a higher-capacity unit. Even running at the same boost levels of a hopped-up stock turbo, larger aftermarket units will produce more power and much less heat due to their decreased resistance to exhaust flow. A fuel-injector replacement may be in order, as well. There is a common delusion among today's hot rodders that the almighty laptop is the solution to all of an engine's horsepower needs. Whereas this is more true on forced induction gas engines than naturally aspirated, the simple fact is that the electronic revolution has far from delivered on the promise of massive power at the push of a button. Failed to deliver, that is, with one notable exception.
Diesel engine tuners are one of the few modifiers that make massive claims to power and actually deliver. Diesel engines by their very industrial nature have immense stores of untapped potential, much of which can be unleashed with a few simple calibration changes.