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Absorbed Power
Inertial Dynamometer vs. Brake Dynamometer
Inertial measurement is highly repeatable, simple, and easy to control. You just accelerate and the results will show the power curve with high repeatability. However, there's something that inertial measurement cannot do, and that's controlling the load received by the engine. You cannot have the engine or vehicle under load at a constant speed; there must always be acceleration. For certain professional applications, it's necessary to apply a constant load, and that's where a brake dynamometer, also known as absorption dynamometers, is needed.
Absorption Dynamometers
Power absorption dynamometers are dynamometers that basically convert the energy delivered by the engine into heat. In contrast, inertial dynamometers convert it into rotational kinetic energy (which will later also convert to heat at the end of the test with the test bench's own brake).
The most common absorption dynamometers are electromagnetic eddy current type and hydraulic type. In both cases, the energy is dissipated as heat that is transferred to the air or cooling water.
Measuring Power
It's one thing to talk about the measurement method and another to discuss how the electronic system and software can read the information generated by that measurement. This involves various parameters like sampling frequency and precision of measurements and sensors. It's a balance, sometimes a compromise between improving one parameter at the expense of another.
The Design
The Recipe
This is where we differentiate ourselves from other measurement systems. The choice of sensor type, measurement timing, algorithms used to transform these measurements into real physical values of rotational acceleration, and from there processing this data to obtain RPM, Torque, and Power. The ingredients are the same for all data acquisition system manufacturers, but the recipe and preparation is where we differ from each other. We prepare a Michelin-star restaurant dish at McDonald's prices.
The Ingredients
The acquisition system consists of 3 elements: the sensor, the electronic interface that captures data from the sensor and transfers it to the computer, and the software that takes this raw data and processes it to display it to the user in the most useful and simple way possible, making it easy to digest.
The Support
Washing the Dishes
In every good restaurant, as in every mechanical workshop, there's work that the customer doesn't see and often takes the most time and care - customer service. Our customer service is how it should always be: personalized, direct, one-on-one. We know you don't read manuals. We don't either. That's why we upload videos, maybe fewer than we should, but we're trying to improve. Meanwhile, we respond to your WhatsApp messages, resolve your doubts, and send you the link to the manual page you need to read.
The Fly in the Soup
Sometimes unfortunately a fly falls in the soup. And it doesn't have to be the end of the world - not as long as you can quickly call someone who will help you solve the problem.
We first listen to your complaints, and after those minutes of venting, we help you find the fault. We'll ask you many questions, request photos and videos to try to diagnose the problem. We'll also ask if you've already tried solving it by turning the equipment off and on. But we'll always be there accompanying you until we find the solution.
Real Applications
Who is it for?
This kit works on engine test benches (engine dynamometers) and roller test benches (chassis dynamometers). Installation is very simple. On one hand, we need to mount a rotation sensor that works with a magnet mounted on some rotating part of the dynamometer, or on the roller in the case of chassis dynamometers. On the other hand, we'll need to mount a load cell on the brake dynamometer to measure the force being applied (torque). If you want to know more about installation, you can consult the online manual.
There are no power limitations. It's the same electronic device and software for both a 10 HP test bench and a 1000 HP one.
The Real Limits
So the true limits aren't imposed by the system, but are defined by the power absorption capacity and maximum torque of the dynamometer, in conjunction with the roller's inertial mass.
Combined Measurement
All Accudyno Forza measurements are the combination of two components: the power absorbed by the dynamometer, which is measured with the load cell, and the power delivered by the engine, which has been converted into rotational kinetic energy. This rotational kinetic energy wasn't measured by the load cell, as it never reached the dynamometer but remained on the way, and needs to be measured.
For this reason, all our systems measure inertial power, which is combined with absorbed power, to show total power. This calculation mechanism allows measurements to be taken with the engine accelerating and it's not necessary to stabilize it at fixed RPM steps.
What Can I Measure?
You can measure power, torque, rpm, acceleration times, as well as additional connected sensors like lambda probe or pressures. The system also performs climate correction, so you'll have power and torque values corrected and normalized by the SAE Correction Factor. We can also measure friction losses, which allows us to estimate the power output from the engine on rollers, not just the power that reaches the wheel.
The Forza system has a control output that can control the dynamometer through variable voltage. A dynamometer power controller with PWM input or variable voltage input is required. This controller is usually provided by dynamometer manufacturers.
Typical uses are engine power benches with hydraulic dynamometer, air-cooled eddy current dynamometer, or water-cooled eddy current dynamometer, roller power benches with any type of dynamometer. It can also be used in AWD rollers that have only 1 dynamometer.
