How does a Dynapack work?
The theory of operation, and the implementation of that theory, is actually fairly simple. However, it took DYNAPACK several years and a lot of hard work 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 needed. Simultaneously load and hub rpm are measured, so the amount of work being performed can be determined. 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 a precise and powerful loading device is needed, the Dynapack uses hydraulics. Hydraulics are incredibly powerful, yet precise. Giving us total control over the axle; we can hold an engine at any RPM (+- 1 rpm) at any power level --> all the way up to the rated maximum torque capacity of our dyno (4000 NM!!) for as long a period of time as you would like. If the software would allowed it, the engine could be stopped within one revolution of the crankshaft... Obviously, you would not want to do this ;), but it gives an idea of just how much power and control the Dynapack offers over the axle.
Our dyno controls the car, not the other way around.
We control the axle speed and rate of acceleration at all times, it allows you to see exactly what the vehicle is doing at any given point in time and RPM of the completed run. Because we aren’t limited by the capabilities of eddy current brakes and similar devices, we open up a whole new world of tuning possibilities. Times change and technology evolves.
How is a Dynapack different?
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 tire distortion including noise, torque steer, loss of traction, tire heat and design variations in the tire.
The first and most obvious difference is the elimination of the tire 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 tire slip, no rolling resistance, and no chance of the vehicle separating from the dynamometer at high speeds. Notice that we call this a variable. tire temperature, tire pressure, tire 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 the Dynapack offers. 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 occurring.
What if you eliminated the flywheel effect? Whilst every spinning mass has some inertia, when compared to the total mass of the wheels, tires, 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.
Dynpack advantages over a normal roller dyno;
- Precise engine results, no inertia to mask faults
- No wheelspin possible
- Repeatable, accurate back to back runs within 0.3%
- Stress free; 2 to 30 sec. runs for all data types
- Minimal noise level since there is no tire interface; improves hearing of engine sounds
Our Dyno runs are repeatable to better than 0.3%. No other chassis dyno is even close to the level of repeatability a Dynapack can achieve. One large reason for this because a Dynapack 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. When you have this variable link in your data chain, you cannot have guaranteed repeatability. Sure a roller dyno itself may be repeatable, but as soon as you put a car on it, all bets are off. 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. The Dynapack is absolutely the most consistent and repeatable chassis dyno in the world.
A Dynapack 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