The theory of operation, and the implementation of that theory, is actually fairly simple. It took several years and a lot of hard work however, to make it as simple as it is today. The hub of the vehicle is directly attached to a hydraulic absorption unit. We can apply a variable but precise load - all the way up to a hydraulic lock if we needed to. Simultaneously we are monitoring load and measuring the hub RPM, so we can determine the amount of work being performed. It sounds easy until you realize that all of these calculations are very complex and are happening very quickly. Add to this, all of the data logging functions and real-time full-color graphics that are also being calculated, and you begin to realize that what appears to be simple is actually very complex. Being the best is never easy.

Because we need a precise and powerful loading device, we use hydraulics. We do not use inertia, we do not use air, we do not use eddy currents, and we do not use friction. Hydraulics are incredibly powerful, yet precise. We have total control of the axle. Literally. Want to hold a steady RPM? We can hold an axle RPM (within 3 rpm) for a stable engine at any power level - all the way up to the rated maximum torque capacity of the dyno for as long a period of time as you'd like. If the software allowed it, we could stop the engine within one revolution of the crankshaft. Obviously, you would not want to do this, and our software prevents it, but it gives you an idea of just how much power and control we have over the axle.

Our Dynapack controls the car - not the other way around.

Dynapack™ chassis dynamometers are such a radical departure from the stereotypical roller dyno that it really is in a class of its own. Most of the previous assumptions made about traditional dynamometers simply do not apply to the Dynapack™ series. In fact, you will discover that we give you tools and capabilities that have previously been thought impossible to achieve on a chassis dyno. Dynapack™ allows you to quickly and accurately measure engine, drive line and other performance data, with previously unseen sensitivity.

Dynapack™ attaches directly to the axle(s), thereby overcoming all the disadvantages of tyre distortion including noise, torque steer, loss of traction, tyre heat and design variations in the tyre.

•  Precise engine results - no inertia to mask faults
•  Repeatable - accurate back to back runs within 0.3%
•  Portability - on and off site
•  Stress free - 2 to 30 sec. runs for all data types.
•  Minimal noise level - no tyre interface
•  Virtually no installation and running costs
•  Cost effective - chassis and engine dyno capable
•  Flexible, easy to use software

The first and most obvious difference is the elimination of the tyre to roller interface on a traditional roller dyno. The Dynapack™ eliminates this variable by using a variable fit hub adapter that provides direct coupling to our power absorption units. There can be no tyre slip, no rolling resistance, and no chance of the vehicle seperating from the dynamometer at high speeds. Notice that we call this a variable. Tyre temperature, tyre pressure, tyre traction, etc. are all variables that can change not only from run to run, but during the run as well.

Throw an unknown variable like this into the equation and your data has now become subject to a potentially high margin of error. It is obviously better if this can be eliminated - which is what we have done. What you end up with a traditional roller design is a giant, heavy flywheel attached to your engine. The inertia is such that just trying to accelerate the mass of the roller is a substantial load for the engine.

Will your measurements be affected by being subject to this large heavy flywheel phenomenon? And will small fluctuations in power delivery be easily noticeable?
In a word, no. The flywheel effect tends to take small rapid fluctuations and smooth them right out. This is great if you want your power curve to look like a smooth pretty line, but it doesn't give you much insight into what is really occuring.

What if you eliminated the flywheel effect? Whilst every spinning mass has some inertia, when compared to the total mass of the wheels, tyres, rollers, and other associated hardware in a traditional roller dyno, the inertia in the Dynapack™ is practically zero.
This allows us to precisely measure and display tiny rapid pulses and oddities that you may not have ever seen otherwise.

Another benefit of having virtually zero inertia is the ability to change the rate of acceleration at will. In many simulations, you may want to make the vehicle accelerate at a different rate to simulate a specific condition. With a few simple keystrokes, we can allow the vehicle to accelerate very quickly, very slowly, or anywhere you’d like in between.

Because of the lack of inertia and the total control we have over the axle speed, we give you choices. And as you know, choices are good!

This makes Dynapack™ an outstanding choice in chassis dynamometers whilst establishing a new industry standard.

The major components are:

Power Absorption Units
Each Package is supplied with two in a two-wheel-drive configuration, and four in a four wheel-drive configuration. Each unit is supported by wheels to allow easy movement around the shop area. The hydraulic pumps are mounted on a pivot that automatically compensates for camber or an uneven floor. There are data cables that connect to the main controller, and fittings to attach water hoses for cooling.

Hub Adapters
Four and five lug adapters are provided as standard equipment. These adapters are attached directly to the axle in the same manner as the vehicle's wheel. The adapters use a sliding washer design that is self-centering and, when properly installed, keeps the runout of the shaft to a minimum.

Cabinet
A cabinet houses the computer, printer, Backup UPS, and controller unit. The top of the cabinet has a platform for the monitor, keyboard, and mouse. The cabinet features toolbox style wheels for easy movement. The cabinet occupies a floor space of approximately twenty-four inches square.

Controller
Housed in a tower-style computer case, the controller performs the electrical control functions for the power absorption units. A data cable connects the controller to the power absorption units.

Computer
The purpose built PC allows the Dynapack software to operate in Microsoft Windows, and operates with simple combinations of mouse and keyboard commands. All data can be saved and recalled for viewing at a later date, and data can be imported in other programs such as Notepad or Excel for other statistical analysis.

Printer
An A4 colour printer is provided for full color printing of statistical data and graphs.

Our Dyno runs are repeatable to better than 0.3%. Other dyno manufacturers claim to be repeatable, but no other chassis manufacturer is even close to the level of repeatability we achieve.  One large reason for this because we have eliminated the largest variable of all - the tire to roller interface.  Rubber tires don't hold traction against a steel roller very well.  Add a year or so of use, and the rollers become polished by the tires and traction decreases further.  Some companies charge extra for special coatings on the rollers - which quickly wear off.  When you have this variable link in your data chain, you cannot have guaranteed repeatability - PERIOD .  Sure a roller dyno itself may be repeatable, but as soon as you put a car on it, all bets are off.  Many people think that this slippage only occurs in high power situations - ask some of the import tuners who have had guys sitting on the bonnet and bumpers trying to get the tires to hook up. With the Dynapack, we use a direct mechanical coupling to make absolutely sure that there is no loss, no slippage, and no inconsistencies in this area.  We have virtually no inertia to mask small details and we use hydraulics for the ultimate in sensitivity and precision.  The Dynapack is absolutely the most consistent and repeatable chassis dyno in the world.

Sensitivity:
We can reliably measure minute differences not seen on other machines.

Some examples include:
.010" change in spark plug gap
Differences between various lubricants
The alternator load when the headlights are turned on (in real time as well)
A single step fuel jet change
Different spark plugs