Dynamometer offer

Methods of measuring engine torque and power

The issue of testing internal combustion engines is quite complex. Correct measurement of power and torque requires consideration of a number of factors. Depending on our purpose and the way we use chassis dynamometers, we can basically point to three solutions – inertial measurement (during acceleration), measurement in load mode (during acceleration), measurement with force balance (braked). The dynamometers we manufacture can work in all these configurations – it just depends on their options and equipment. We will continue to call dynamometers equipped with brake or electrospinning brakes as load dynamometers. We will continue to call dynamometers operating in inertial mode, not equipped with a brake, as inertial dynamometers. Note: without exception, all the dynamometers we offer are equipped with elevators that elevator cars off the rollers together with a brake that locks the rollers – do not confuse the roller brake with the electrospinning brake.

Inertial measurement (measurement method possible on inertial and load dynamometers)

Inertial measurement involves accelerating the car on the dynamometer and then, after decoupling, waiting for the car to stop, without using the brake. The load on the engine is the weight of the rollers and rolling resistance, as well as the resistance of the drive mechanism. Measurement time is about 10-30 seconds of full load and a few minutes – free rolling on the dynamometer until stopping. Power and torque are measured, as functions of the car’s acceleration on the rollers (power, wheel torque) and its deceleration (power and loss torque). Their sum forms a result representing the engine’s power and torque.

Inertial measurement has several important advantages over measurement under load:

• requires a shorter full load time – so it is safer for the engine,
• does not require expensive car cooling systems – a medium-sized fan is sufficient,
• is more accurate because the brake strain gauge and the limitations of the brake’s controllability and thermals degrade the accuracy in load measurement.

Inertial measurement also has several disadvantages:

• Very powerful turbine engines may require a high load to properly “build” the boost. A brake dynamometer does not have this problem – the load can be increased as desired, only slightly degrading accuracy,
• The inertial dynamometer does not allow the car to be tested in constant-speed mode.

The inertial measurement process goes as follows:

• The vehicle enters the dynamometer. The elevator lowers the car onto rollers and unlocks it,
• The car is aligned and then secured to the measuring station with straps,
• The transmission and drive ratio is tested – this can be done in several ways. The information is entered into the dynamometer program. The blower fans are activated,
• After making sure that the engine temperature is already correct, the driver accelerates the car in the gear of his choice to the desired speed (usually – to the so-called “cutoff”),
• The driver depresses the clutch, leaving the gear engaged. The dynamometer slows down until it stops. The result of the measurement is presented on the screen. The tuner can analyze the results obtained (power, torque, mechanism and rolling resistance, power at the wheels, results of measuring instruments on the dynamometer’s equipment, etc.) depending on the speed.

Measurement in dynamic load mode (measurement method possible on load dynamometers)

Measurement in this mode looks similar to the inertial mode with the difference that the electrospinning brake simulates a higher load. The load index is a percentage, determined in the dynamometer program by the user.

Measurement in dynamic load mode has several significant advantages over inertial measurement:

• The user can independently select the load depending on the type and power of the engine under test,
• The possibility of extending the measurement time,
• The ability to properly load powerful turbine engines, in order to properly “build” the supercharger.

The measurement process in dynamic load mode is as follows:

• In dynamic load mode, before the start of the measurement, it is necessary to set an additional load in the dynamometer program (that is, to increase the apparent inertia of the dynamometer by loading the car with the electrospinning brake to a degree that does not balance its torque). This allows you to precisely match the load to the engine’s power, for example, in order to correctly “build” and maintain supercharging,
• The procedure for the actual measurement, once the load factor is determined, is identical to the inertial mode.

Load measurement at constant rpm (measurement method possible on load dynamometers)

Load measurement at constant RPM involves balancing the driving force of the car with an electrospinning brake and calculating the engine power from the data from the strain gauge (force sensor). The measurement time is about 10 seconds of full load (to stabilize the revolutions and read the result) for each measurement point (specifically selected revolutions).

Measurement with load at constant speed – advantages and disadvantages:

Because the measurement of engine power on a dynamometer with a brake (with the load in drive balance mode) is subject to greater error, but allows the car to be held at one speed of interest – it is most often used for forcible testing of engines and powertrains. Brake-equipped dynamometers are purchased from us by companies researching new control systems, fuel injection, constructing high-performance engines. The great advantage of such a dynamometer is that you can tune the car in real time at specific points, although of course you have to be aware of limitations, especially thermal ones. The car under full load produces the highest possible amount of power for the selected rpm, and thus the amount of heat. Unfortunately, as a result of such work, the engine heats up and changes its parameters (its efficiency decreases), despite intensive cooling. No fan can replace the air duct with a wind speed of about 200 km / h – after all, in such a “channel” moves a car driving fast on the highway. The car behaves in a reproducible manner only during a few tens of seconds of full load. Such a mode of measurement requires a good test method, effective cooling and consistency of the researcher’s work.

The measurement process in constant-speed mode is as follows:

• The researcher specifies in the program the measurement points during which the rotation is stabilized,
• The driver accelerates the car, pressing the accelerator pedal fully (if the measurement is to be made for full throttle). The dynamometer automatically loads the car until the rpm is as high as the set value and the car neither slows down nor accelerates. The power value, calculated from the strain gauge readings, is presented on the screen in real time. The tuner can make changes during the measurement and immediately observe the effects of his work on the screen.

Other measurement capabilities

Road mode

The car accelerates in a manner similar to road conditions. Based on the input, the electro-rotor brakes generate a load similar to the forces resulting from air resistance and hills, depending on the car’s current speed.

Driving cycles

The ability to perform so-called driving cycles according to a self-configured scheme or one selected from the available database (e.g. EUDC test involving simulation of driving in non-urban conditions). We use the driving cycles, among other things, to test the level of exhaust emissions, fuel consumption, etc., or to carry out LPG/CNG installation calibration.

What does our power measurement technology offer you?

Huge speed of information gathering

The fundamental disadvantage of existing dynamometer solutions on the market is their sampling frequency. On the charts from the dynamometer of many companies you can clearly see a few or a dozen dashes, from which the shape of the characteristics is approximated to the real one. Of course, it is sometimes possible to smooth the graph with curves, but can this be considered a real result? Most often, a sample of power and torque is performed on the dynamometer every 0.3-1.0 seconds, and the established result is de facto the average power and average torque over such a time interval. As a result of such techniques, twice measuring torque that changes rapidly (as in turbo diesels) gives two different results. It depends on how the sampling intervals are arranged.

Several years ago, our company developed a new torque measurement technology that is applicable to both brake and inertial dynamometers. Originally, the measurement method was addressed to the needs of laboratory power measurements, but it is also in our commercial offer. The method is based on our patented TrueForce™ technology, allowing torque to be measured completely smoothly. From the point of view of the rate of change of forces on the dynamometer, the measurement is made in real time and with immeasurable accuracy. In fact, every second of measurement, the dynamometer’s encoder provides up to three thousand instantaneous torque and power information – one linearly independent measurement point is placed on the graph as often as every 0.0003 seconds. The error of determining the time instant is less than 0.00001 s. What’s more – such accuracy is offered, as standard equipment. On the charts, changes are smooth. Why? Because the operation of the motor and changes in torque are also not stepped, due to the high inertia of its own. The accuracy of the measurement is so high that the graph is smooth and does not wobble, but the interruption of the measurement or even the smallest disturbance is mercilessly caught and the engine speed for which it occurred can be indicated very precisely. It is possible to observe subtle phenomena such as instantaneous resonances, wheel slippage (the position of the rollers is known at all times to fractions of an angular degree) or minimal torque “forfeits” when equalizing boost pressure. What’s more – even single misfires reduce engine torque and are visible despite the existence of the flywheel! What’s more, the results are reproducible across multiple tests (as long as you take care to keep the engine temperature constant and don’t repeat the tests one after another too many times) until you get bored. All this without any smoothing, without averaging, without recalculating by imaginary percentages and ratios. No other solution offers such accuracy and precision – you simply have to see it to fully appreciate TrueForce’s capabilities.

Very high measurement accuracy and high repeatability

The advantage, resulting directly from our novel measurement method, is really high repeatability. Since the rotation of the roll is measured extremely accurately, torque and power measurements and the positioning of points on the chart are also accurate. Due to good bearings, high inertia and very precise balancing, the measurement accuracy is also higher than in other competitive solutions. The dynamometers are furthermore calibrated with a gravity torque standard, which guarantees correct indications of the measured absolute values.

Easily expandable and modular solutions

Probably everyone who decides to spend tens of thousands of zlotys on a device they need, such as a dynamometer, would like to know what to do next, what to do when their needs increase.

Our solutions are fully modular, giving the possibility to upgrade a single-axis dynamometer to a two-axis dynamometer, inertial version to a load version, retrofitting the test stand with external sensors: temperature, pressure, or mixture composition. All the necessary dimensions and conditions for the installation of individual options can be provided in advance in the form of blueprints, so the user can check the suitability of his dynamometer room also for future expansion.

Popularity and credibility of the manufacturer

Our solution has already been chosen by more than 100 companies at home and abroad – including many well-known and popular Polish tuners and specialist companies! We are the largest dynamometer manufacturer in Central Europe. You can find the graphs produced by our measurement system everywhere – on the Internet, in newspapers, in the hands of those who test their cars on our dynamometers. The results from our dynamometers coincide with each other thanks to the calibration of the finished dynamometers in our company. Our system is widely known. Only in the country we install one dynamometer per month. Abroad, our dynamometers work in Spain, Great Britain, Ireland, Germany, Greece, Romania, Lithuania, Latvia, Russia, Norway, Sweden, Finland, among others.

Impeccable workmanship to enhance the prestige of the holder

Each component of the dynamometer is powder-coated, in addition, the top covers are protected with an anti-corrosion layer. The rollers are made using the edgeless method (no visible welds), then they are moled, covered with technical chromium and balanced with an accuracy of 0.5g. Each dynamometer is equipped with a pneumatic brake that locks the rollers during entry and exit of the measuring station. The control computer is placed in professional industrial enclosures – similarly, the electrospinning brake controller. The entire control is placed in a 19″ industrial rack or in a special desktop. All necessary components are supplied in the set. On the printouts and protocols are presented the address data of the buyer, and the chart as a background can have any logo placed.

Which dynamometer should you choose?

Since a dynamometer is not an inexpensive piece of equipment, it’s a good idea to know exactly which options you need and which should be abandoned or invested in later – as your dynamometer needs and load grow. You may have already known specifically what you need for a long time – or formed an opinion by reading the above description of how each type of dynamometer works.