Dynapack vs Roller Dyno’s

The first and most obvious difference is the elimination of the tire to roller interface on a conventional roller dyno. The Dynapack eliminates this variable by using a hub adapter that provides a direct coupling to the Power Absorption Units. There can be no tire slip, no rolling resistance, and no chance of the vehicle coming off of the dyno at high speeds. Notice that this is called a variable. Sometimes it may be a problem area; other times it may not. Tire temperature, pressure, traction, etc., are all variables that can change, not only from run to run, but also during the run. 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 these variables are eliminated, which is exactly what we have done.

Why We Trust Dynapack

There are other associated problems with the roller method as well. Take tie-down straps for example. Most roller dynos use ratcheting tie-down straps to attempt to hold the vehicle in position while being tested. If the straps are cinched down tightly, the tire has become loaded even further in an unpredictable manner. While this may be good for enhancing traction, it changes the rolling resistance of the tire, skewing the data even more. Since these tie-down straps aren’t perfect, the vehicle squirms around on the rollers dramatically changing the tire drag during the run. If the vehicle is tested in two different sessions, the straps can’t be set exactly the same way twice. Again, the data will be inconsistent. There have been cases where the ratcheting tie-down straps were loosened by two clicks and the measured power increased by ten horsepower. What if the straps stretch, either from run to run or during the run itself? Wouldn’t it be great if all of these problems could disappear? With a Dynapack, they were never there in the first place.

Repeat-ability

Dynapack 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 repeat-ability the Dynapack achieves. One large reason for this is because the largest variable of all has been eliminated–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 repeat-ability. Many people think that this slippage only occurs in high power situations, but we’ve seen it happen with 250HP Hondas. We have even seen some tuners have guys sitting on the hood and fenders to get the tires to hook up.