Our 4wd Chassis Dynamometer
What makes our dyno different from all the conventional 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 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. We'll 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 the Dynapack does.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've all 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 stretches - 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!
Our Dyno runs are repeatable to better than 0.3%. Other dyno might claim to be
repeatable, but no other chassis dyno is even close to the level of
repeatability our Dynapack can 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. 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, but we've seen
it happen with 250HP Hondas - ask some of the import tuners who have had guys
sitting on the hood and fenders 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. 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
No other shop/tuner in Illinois can offer its customer with the type of service
or capability that we can because of this piece of equipment. The dyno is not
just a tuning tool but a diagnostic tool as well. We've been able to find
problems with certain area of the cars power band that customers weren't able
to feel on the road, at the track or read on any inertia dyno. Our dyno allows
us to tune for a smoother torque band therefore a faster smoother car on the
track or the road. |
Current Chassis Dyno Rates
Baseline
2WD Cars - $100
3-5 Baseline power runs with color graph print out of torque, hp and Wideband -
No tuning
4WD Cars - $150
3-5 Baseline power runs with color graph print out of torque, horse power and
Wideband - No tuning
$25 setup fee for Automatic cars
Tuning
2WD Cars - $145 First hour and $100/hour thereafter with Wideband
4WD Cars - $200 First hour and $150 thereafter with wideband
$25 setup fee for Automatic cars
Test and Tune
25% discount on your next baseline pulls if you return within 3 days.
Same car only. Not applicable with tuning services.
Optional monitoring and Services
Boost $15
3.5 Floppy with data $5
Extra printouts $5
|
