Mustang Dyno Jet Test - The Jet Set - Tech

While the DynoJet certainly provides repeatable data, if the motor won't cooperate, how can you distinguish between power changes offered by the performance upgrade and those offered by changes in timing and or air/fuel? This question is one of the reasons I love testing with the guys at Kenne Bell. They go the extra mile and data log every variable in the ECU. This way, they know why one run is higher or lower than another. Using the available software for the Ford motors, they can then lock out all the variables to ensure perfectly repeatable results.

Unfortunately, for the rest of us mortals, we don't have access to the data-logging equipment employed by Kenne Bell-or do we? One of the new offerings from DynoJet is the Datalink Module. What the Datalink does is allow DynoJet owners to log all of the data provided through the OBD II port on all '96-and-newer vehicles (not just Fords, but all vehicles). This means in addition to the usual horsepower, torque, and air/fuel readings, enthusiasts can view and overlay things such as spark advance, inlet air temperature, and coolant temperature. In fact, any of the parameters provided by the OBD-II port can be viewed and logged and then (using WinPep 7 software) charted against the power, torque and air/fuel curves. Many shops now have this software.

The Datalink Module allows users to determine not only that there were changes in the power curve, but why these changes occurred. It also allows tuners to ensure that each dyno run is made at the proper air and coolant temperatures, thus ensuring identical ignition curves. On our own test vehicle (an '01 Ford Focus), the new Datalink Module system was put to immediate use even before we installed the AEM air intake system or the Focus Sport long-tube header and flex pipe. Since we were looking for relatively small power gains on this stock 2.0L Zetec, we needed the motor to be perfectly repeatable. Unfortunately, the little Ford motor had other ideas.

Running the car on the DynoJet in three successive runs resulted in relatively good results for run No. 1, then the power dropped off by 10 hp or more on the subsequent runs. While that may not seem like much to the owner of a supercharged Mustang, it represented a change of nearly 10 percent on this stock 2.0L. Without the information supplied by the Datalink Module, you might be tempted to attribute the loss of power to a hotter motor, but such was not the case. The Datalink showed us that the ECU was pulling timing not based on ECT but on ACT. Despite having the hood open, the inlet air temp to the stock airbox (sans fresh-air tube) increased by 55-60 degrees, resulting in a drop in ignition timing of as much as 7 degrees (with a corre-sponding loss in power). Before we could hope to successfully test the minor gains offered by the cold air and header systems, we had to have a repeatable baseline. Adding the stock fresh-air tube produced the desired results.

While DynoJet obviously ushered in the age of chassis-dyno testing, its systems have not been faultless. The two major complaints lodged against the chassis-dyno systems include the lack of load control and external data (in addition to that provided by the new Datalink). I, for one, have long wished that the information provided by the DynoJet software included such things as boost pressure, inlet air, and even exhaust-gas temperatures. It looks as if I wasn't alone in my desire for more data, as DynoJet recently introduced a new Thermocouple Amp.