| |
|
Speed Shop Dyno Tuning
Get
All the facts before you ever consider a competitors flawed equipment.
Introducing the Dynapack chassis dynamometer: Thank you for your interest in our products! The Dynapack is a truly revolutionary machine. In the following pages,
we will attempt to answer all of the most commonly asked questions we receive, while at the same time, provide some technical
insight on the way we achieve the results we do. There are some very important differences between our products and others
in the marketplace. We have no interest in making disparaging comments about our competitors, but we do feel that it is important
to make sure that these differences are explained clearly in order to demonstrate the full potential of our products. Dynapack
chassis dynamometers are such a radical departure from the stereotypical roller dyno that it really is in a class of it’s
own. Most of the previously developed assumptions about chassis dynamometers (the roller type) simply do not apply to the
Dynapack series. In fact, you will discover that we give you tools and capabilities that were previously thought to be impossible
to achieve on a chassis dyno.
How does the Dynapack work?
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 our dyno as simple
as it is today. The hubs of the vehicle are directly attached to hydraulic pumps. We can apply a variable but precise load
with all of the potential holding power that hydraulics possess. Simultaneously, we are monitoring pressures and measuring
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. Traditionally, most serious engine builders have thought that chassis dynamometers were inferior to the
results you could obtain from a quality engine dyno. We have effectively attached engine dyno style load cells to the axles,
so we now have the type of precision and repeatability normally associated with an engine dyno, but with the convenience and
benefit of having the engine operate in its natural environment - which has enabled many of our customers to see better results
than they were getting on their engine dyno.
Because we need a precise and powerful loading device, we use hydraulics.
We do not use inertia (more on that later), we do not use eddy currents, air, or friction. Because of the incredible holding
power hydraulics offer, we have TOTAL control of the axle speed. Literally. Want to hold a steady RPM under high power? We
can hold an exact axle RPM (+/- one RPM) at any power level - all the way up to the full maximum rated torque capacity of
the dyno, CONTINUOUSLY - for as long as you like. If the software allowed it, we could stop the engine within one revolution
of the axle - even if the engine is at full throttle at its maximum torque level. Obviously you would not want to do this,
and our software prevents it, but it does give you an idea of just how much power we have over the axle speed. Our dyno controls
the car - not the other way around. We control the axle speed and rate of acceleration at all times. 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. What was once “industry standard” is now yesterday’s technology. The
Dynapack is truly the most technologically advanced chassis dynamometer in the world - at any price.
 What does a Dynapack package consist of? Each Dynapack system sold in the USA comes as a complete package - ready to
run.
The major components are:
Power Absorption Units (Pods)
Each package comes 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 shop
floor. There are data cables that connect to the main controller, and fittings to attach water hoses for cooling. Since the
pods are mobile, they are easily rolled out of the way for storage when not in use - saving valuable shop space.
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.
Additional adapters for custom applications are available on a special order basis. If you can bolt a wheel to it, we can
fasten the dyno to it. Some vehicles may require special adapters or spacers - ask your Dynapack representative for details.
InnovateMotorsports Air/Fuel ratio Meter w/ Dynapack interface
Measures actual air/fuel ratio in gas, alcohol, diesel, and LPG applications.
Data is displayed on the computer screen. As with all Dynapack data, it can be plotted against time or RPM on a graph
and stored in the vehicle's data file. Dynamometers can be equipped with dual meters as an option.
Temperature Sensor
Humidity Sensor
Barometric Pressure
Sensor
How is a Dynapack different?
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 our 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 we call this 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 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 these variables could be eliminated - which is exactly what
we have done. 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 further. 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 in a row. Again, the data will be inconsistent.
We have heard of 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.
Another
major difference is the effect of inertia. Street wheels and tires spinning at high RPM have a large amount of inertia. A
large steel drum spinning at the same ground speed has much more inertia. What you end up with 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. That is the principle that some roller dynos (or “inertia dynos” as they are also called) operate
on. Accelerate a known mass to a measured speed over a given time and it can be calculated to equal a certain amount of power.
There is nothing wrong with this theory, but like many theories, its application in the real world can be troublesome. How
do you think your measurements will be effected by being subjected to this large heavy flywheel phenomenon? Will small fluctuations
be noticeable? In a word, no. The flywheel effect tends to take small rapid variations and smooth them right out - as energy
that should be going into the dyno is being wasted trying to accelerate a large lump of steel. 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? While nothing that has a spinning mass has “no” inertia, when
compared the total mass of the wheels, tires, rollers, and other associated hardware of a roller dyno, the inertia of a Dynapack
is practically zero. This allows us to precisely measure and display tiny rapid pulses and oddities that you may not have
seen before. Now you have a window into areas that no roller dyno will allow you to see. Another benefit of having virtually
zero inertia is the ability to change the rate of acceleration at will. In many situations, you may want to accelerate the
vehicle at a different rate to simulate a specific condition. With a few simple keystrokes, we allow you to make the vehicle
accelerate very quickly, slowly, or anywhere in between. Because of our lack of inertia and total control of the engine
speed, we give you choices that none of our competitors can even dream of - and as you know, choices are good!
|
|
 |
