Richard Holdener
June 1, 2007
There's no better way to determine the power output offered by performance components than testing on the DynoJet.

It's true what they say about your first time in that you never forget it. For me, the magical moment took place in the wee hours of the night in the last driveway of a deserted industrial park. All the shops and office buildings had long since closed, the hunter's moon and chill of the night air signaled the approach of the bewitching hour. A silence gripped the darkness, but as luck would have it, not my midnight mistress. The night air was summoned to life, first with a deep growl, then with the long, pronounced wail of some unseen mechanical banshee. There was something seriously wrong with making this kind of racket after midnight (on a school night, no less), but the huge grins hid any trace of guilt.

The motor on the supercharged SHO Taurus wailed again. At the time, we weren't sure if the noise was in protest or celebration, but that supercharged 3.0L V-6 continued on its way, forcing the tach needle ever closer to the magic 10,000-rpm mark. Recognizing that hefty and potentially devastating chunks of aluminum and steel were currently orbiting at the near-escape velocity of 166 times per second, we gave the mayhem the requisite O.S.H.A.-mandated safety distance.

The DynoJet 248 is the chassis dyno that started the revolution. DynoJet now offers an upgraded version of the original 248 (called the 248X) as well as a heavy-duty version (the 248HW) designed for testing turbo-diesel truck applications equipped with dual rear wheels.

The small crowd outside Kenne Bell's Southern California facility stared in disbelief at the chaotic commotion no more than a foot away. What made all this midnight fun possible, not to mention memorable? A DynoJet chassis dyno, and a portable one at that. Trying to fight back my ever-widening grin, I remember thinking, this impressive device is going to change the automotive industry.

Having started in the industry long before the proliferation of chassis dyno testing or (more importantly) tuning, the DynoJet has been all but a godsend for me. I can remember when I started at McMullen Publishing (now Primedia), I was anxious to get into some serious automotive testing. Back then, almost no one had a dyno, and those who did, had engine dynos. While engine dyno testing is important (not to mention loads of fun), much of our testing involved actual vehicles. I fought tooth and nail just to get the publishing company to purchase a Vericom acceleration computer. I wasn't about to just print the power numbers and attending acceleration improvements offered by the various manufacturers.

Left: Due to its affordable price, power-measurement capacity, and small size, the new 224X has become DynoJet's best-selling automotive chassis dyno (shown with optional four-post lift).

If the gains were there, I wanted to test them. Needless to say, I was viewed with some disdain. You have no idea how many times I heard statements like, "Come on, Holdener, it takes too much time and energy to take vehicles to the dyno or even the track for testing." Some were satisfied with the results of their butt-o-meter (it feels faster-so therefore it must be faster). The accuracy and calibration of their derriere notwith-standing, I knew I couldn't tell the difference between a 10hp gain and a 15hp gain, especially on a motor that already produced 400 hp. Besides, even if I guessed correctly that the product in question was worth an extra 10 hp, where in the power curve was it better? Was it 10 hp better everywhere, or did it sacrifice power at the bottom to make a few extra at the top? My questions were many, and unfortunately, the verified answers were few.

Needless to say, I was somewhat less than thrilled about the prospect of chassis dyno testing, that is until witnessing that supercharged SHO Taurus rip the rollers that fateful night. Even before the run was over, I was hooked. I didn't want to test only magazine cars, I wanted to test everything. Just ask guys like Steve Ridout at Powertrain Dynamics, Jim Bell at Kenne Bell, or any of the other DynoJet facilities that I managed to weasel my way into, sometimes until the wee hours of the morning.

These days, DynoJet has sort of become the standard of the automotive industry. By providing access to not only large national corporations, but also to smaller (regional) tuners and performance shop owners, DynoJet revolutionized the performance industry.

The hot news from DynoJet is the availability of the Load Control System which allows users to run sweep, step, and loaded roll-on testing. A simple click of the mouse is all that's required to switch back to inertia mode.

Prior to the advent of DynoJet availability, the "tuning" method for my supercharged Mustang LX was to find my favorite freeway on-ramp and put the power down hard in Third gear (my scientific method included using the same on-ramp for consistency-what a joke.). If the tires spun a little, something was amiss. If they spun hard, the motor was working perfectly and ready for that trip to the Silver State Open Road Race where the car would run flat out for 90 miles. I cringe every time I think about how many times I ran that motor at full throttle for the entire race (except in the narrows posted at 45 mph) without ever having run or tuned the motor on a dyno. Now that I think about it, I even ran all my SCCA World Challenge and Bridgestone Supercar races without the supercharged Mustang ever having seen the rollers (or air/fuel meter). Boy, was I an idiot. As it is now, I don't like driving a new combination down the street without knowing the air/fuel and timing curves are spot on. Boost on an unknown combination? Not on your life.

History has shown that DynoJet chassis dynos began popping up all over the place. What DynoJet brought to the automotive industry was credibility. One need only look back at the issues Ford had with the SVT Cobra to witness the power of the chassis dyno. Armed with a slew of dyno results, Cobra owners made enough of a ruckus to demonstrate that their powerful ponycars did not live up to the promised performance. As a tool, the DynoJet not only gave journalists the ability to verify performance claims made by manufacturers, but the manufacturers the ability to test and enhance its own products (not to mention verifying the claims of insufficient power made by unscrupulous individuals). Before long, performance enthusiasts came to rely on the DynoJet and actually expected their car to be tuned on them.

The decision to bring your supercharged Mustang to a shop for upgrades was made much easier if the results were dyno verified. The chassis dyno could also be teamed with new tuning software to maximize the safe power output of nearly any Ford combination. This ushered a brand-new phrase "dyno-tuned." Not long after the introduction of the tuning software, shops began to use dyno results to compete via the Internet (ethernet bench racing sessions soon evolved).

Offered as an upgrade to existing DynoJet chassis dynos, the 224X AWD system will allow chassis dyno testing of all-wheel-drive applications.

With the DynoJet chassis dyno all but a way of life now in the automotive industry, we thought we would take a closer look at the brand that started the chassis-dyno revolution and see what they have in store for the next trip. Starting the revolution made DynoJet a household name (at least, performance households) and put them on top, but that legendary status won't keep you there for long. Staying on top, especially with so many qualified competitors in the newly formed marketplace, takes a continuing commitment to technology. With shops now able to provide not only horsepower and torque figures, but real-time air/fuel readings thanks to a wide-band air/fuel monitoring system linked to the WinPep software, DynoJet decided to take things to the next level.

Sure, correlating horsepower and torque figures with the air/fuel data is handy for tuning, but today's vehicles have become increasingly more complex. Compared to the processing capabilities of today's ECUs, the original A9L computers used on the SEFI 5.0L Mustangs may well have just been carb jets and points. The sophisticated new computers make testing all the more difficult, or at least testing to achieve both accurate and repeatable results.

With the ECU constantly monitoring and altering both the air/fuel and timing values using a variety of sensors, just making repeatable back-to-back runs (with no hardware changes) has become increasingly difficult. If the motor isn't repeatable within 1-2 hp, how do you properly test components that may only offer 3-4 hp? The answer is obviously that you can't.

The brains behind the DynoJet was this Dynamometer EX+ hardware. The package included an atmospheric sensing module, an rpm module, and a dynamometer input/output module. The CPU module contained a 32-bit processor which acquired data from the expansion modules and communicated this data to the user-supplied computer running the WinPep software.

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.

Though the preferred position for the oxygen sensor is in the exhaust pipe or header before the catalytic converter, it can be employed as a tail-pipe sniffer using this dedicated pump.

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.

Used to enhance the capabilities of the existing modules, the Thermocouple Amp is able to convert any type K thermocouple into a 0-5V-based analog signal. What this will allow is the use of any type K thermocouple to measure exhaust gas temperature, cylinder head temperature, or even intake air temperature (before or after an intercooler). Imagine being able to determine the effect changes in exhaust-gas temperature have on the response rate of a turbocharger or how the ignition timing affects the EGT? Another pair of helpful modules offered by DynoJet include the four-channel analog and EZ-RPM modules. The four-channel analog allows users to log four separate 0-5V sensors-such as boost, fuel or oil pressure-and compare it to the power and air/fuel. The EZ-RPM module provides a tach signal via, of all things, the cigarette lighter.

With the new Datalink, Thermocouple Amp, and EZ-RPM module, DynoJet owners should have no shortage of information, but what about the complaints that the DynoJet was just an inertia dyno and did not offer the ability to run loaded testing? While it's true the original 248C DynoJet offered only inertia testing, DynoJet now offers load control and all-wheel-drive chassis dynos. Currently, DynoJet offers the 224X, the 424X, the 248X, and the 248HW chassis dynos. The 224X is available as an inertia dyno and with the optional load control. According to DynoJet, its Load Control Systems incorporate an ultraprecise and consistent eddy-current load-absorption unit. The system utilizes an integrated torque cell to quantify the power absorption. The tests can then be reviewed and analyzed through the impressive and user-friendly WinPep 7 software. DynoJet understands that time is money in a performance shop and has ensured that a quick and effective calibration routine for the load-absorption unit can be accomplished in less than a minute. Like all the inertia dynos, the Load Control can be configured for either in-ground or above-ground installation.

The 424X from DynoJet is essentially a pair of 224X dynos linked to provide testing for full-time all-wheel-drive applications. Like the 224X, the 424X AWD dyno system is capable of measuring up to1,500 hp per dyno at each pair of wheels. The 424X is even more impressive in that the system is adjustable for wheelbase. Running on an extendable track, the distance between the two dynos can be adjusted to accommodate changes in wheelbase from 88 inches to 140 inches, though custom systems are available to increase this number. Comprised of a pair of 224X dynos, the 424X is capable of running at speeds up to 200 mph and can be further upgraded with DynoJet's new Load Control Systems. This allows tuners to perform step, sweep, and loaded roll-on tests. The Load Control also allows users to run closed-loop testing by targeting the engine speed, vehicle speed, or percentage of load. The Load Control units are securely attached to the rollers by way of a splined shaft. This eliminates issues such as belt slippage or failure and helps ensure superior repeatability. Switching the Load Control System back into inertia mode requires no more than a simple click of the mouse. With a combined capacity of 3,000 hp, the 424X and 424LC AWD dynos from DynoJet can handle any all-wheel-drive performance application likely to come their way.

The AEM system for the Focus mounted the filter down in the inner fenderwell (the bumper was removed in anticipation of the installation of a Roush turbo kit). This filter position provided a dedicated source for cold air.

In addition to the 2WD, AWD, and Load Control versions of the 224 and 424 chassis dynos, DynoJet also offers a pair of 248 models. The 248X is basically an upgraded version of the original 248C. The 248X is capable of running at 200 mph and supporting up to 2,000 wheel horsepower, making it perfect for serious race applications. The 248HW was designed specifically for testing vehicles with dual rear wheels and having axle weights up to 10,000 pounds. The 248HW is wider and offers an increased axle-weight limit compared to the standard 248X, making it highly suitable for testing the crazy turbo diesel trucks that have become so popular lately.

In addition to the many dyno configurations, DynoJet also offers tuning software packages, including SCT, EFILive, and DiabloSport. Combining the tuning software with the impressive chassis dynos make for the perfect combination. In addition to the tuning software, DynoJet has also teamed up with MSD, Nitrous Express, and K&N Performance Filters to produce a PERKS program for Dynojet owners. PERKS allows shop owners with DynoJets to maximize profits by purchasing direct from the manufacturers at a substantial discount. In looking at the current offerings, it looks like DynoJet is serious about staying on top of its game.

Inlet Air Temperature Vs. Spark Advance-'01 Ford FocusHaving a motor lose as much as 14 hp is never a good thing, but it's especially disappointing when you only had 106 wheel horsepower to start with. Using the Datalink hardware from DynoJet, we were able to determine that the dramatic loss in power came from the drastic reduction in timing caused by the change in inlet air temp. The graph shows the ignition timing was down by as much as 7 degrees. The cause was the change in inlet air temperature of nearly 60 degrees (the values on the scale are doubled). Without a repeatable baseline number, how could we properly attribute the change in power once we installed the performance components?

Impressed by the new lineup of dynos and associated components, we took DynoJet up on its offer to test the new products. While we wished we had an old RS200 to run on one of the AWD dynos, or even an AWD Rally Focus, all we had at our disposal was an '01 ZX3. Sadly, the 2.0L Zetec motor currently residing in the engine bay was lacking any semblance of a power adder. Though fresh and new, the motor was disappoint-ingly stock, but fear not, as a Roush turbo kit is en route to change all that. Luckily for us, we didn't really need a high-horsepower car to demonstrate the merits of the new DynoJet offerings. In fact, the wimpy little Focus was the perfect candidate as we needed both precision and repeatability to ensure accurate power readings. When you go looking to make a 10-percent improvement in power on a 400hp motor, it equates to a gain of 40 hp. That same 10 percent change in power on a motor that only produces 100 hp equates to just 10 hp. If you hope to find changes of a few horsepower here and there from simple bolt-ons, you better have a motor (and dyno) that is dead-on repeatable or you're just spinning your wheels.

In the case of our '01 ZX3 Focus, we decided to test the merits of the dyno and new Datalink hardware by making a pair of minor changes. We added an AEM cold-air intake and a Focus Sport long-tube header and flexpipe. Obviously, cold air is always a good idea, so too is good-quality long-tube headers. As we mentioned, the minor mods applied to a more radical combination would yield decent power gains, but on our otherwise stock Zetec, we would be thrilled with a gain of 10 horsepower. Before testing, we established a baseline. The Datalink came immediately to the rescue by illustrating that the dramatic drop in power that occurred over three successive runs was the result of a change in ignition timing.

Further to the point, the offending ignition retard came from a huge change in inlet air temperature. The Datalink system provided the necessary information to allow us to solve an immediate problem. After the installation of the fresh-air tube portion of the stock air cleaner assembly, the motor became perfectly repeatable. We were then free to make the modifications. After installing the AEM intake and Focus Sport exhaust, the power numbers jumped from 106 hp to 118, a gain of 12 hp. Elsewhere on the curve, the gains were as high as 17 hp. The torque gains offered by the combination also exceeded 17 lb-ft., but the best part was learning for certain that the power came from the performance components and not changes in timing, air fuel, or temperature.