Is it like an inertial dyno?

No! Inertial dynos are old concept tools, so today they are useless and outdated. They cannot measure the power and torque but they only give an approximate and estimated calculation of those values, always different test by test. Bapro produces only braked dyno chassis dynamometer (not inertials!), in which every component is designed to take advantage of this type of technology. Braked dynos are able to effectively measure the power at the load cell, in this way they can give you extremely precise and repeatable values. The power is measured during a controlled acceleration reproducing the real behavior of the vehicle on the road, adapting itself to the performances of the vehicle. In this way the engine works in the same way it does on the road, and the values of shaft power given by the dyno are precise and reliable. Moreover, the eddy current brake and its extremely advanced electronic control allow to perform a wide range of tests, useful for diagnostic, tuning and Motorsport: road simulation, constant rpm test, engine tuning test are only a few examples.

Is it like an inertial dyno transformed in braked?

No! An inertial dyno transformed into braked is actually an inertial dyno with the addition of a brake and an electronic control. This type of dyno was born with the concept of inertial dyno, with all their limits, making it impossible to do an efficient and effective transformation into braked dynos. This is the case of all the dynos available on the market in both version: inertial and braked. Bapro chassis dynamometers are only available in braked version with eddy current brake. Among the limits of inertial dyno transformed into braked there is, for example, the huge roller weight, which is strictly needed for inertial dynos in order to have an inertial weight to accelerate. But in braked dynos rollers’ weight must be reduced to the minimum, in order to achieve the maximum precision and repeatability. This is why Bapro rollers are light and empty: inertial weight is minimum and the measured power curve perfectly follows the engine behavior. One more important and significant limit of inertial dynos is the grip offered by the rollers: in inertial dynos the acceleration during a power test is very fast, so a high grip is not needed, this is why rollers are often smooth, or knurled by tracing. But, if after that, inertial dynos are transformed into braked, grip will be necessary! Otherwise slippage of tires on rollers will appear, badly affecting the test, with the additional risk of tire’s explosion. But during the transformation into braked dyno the rollers cannot be replaced… For these reasons the rollers of Bapro dynos (which are born braked) are knurled thanks to CNC cutting tools, delivering high grip and a brand-new surface even if after THOUSANDS of tests. In this way they guarantee an absolute result and the repeatability of the test.

Can it measure the power on the wheels?

No! A chassis dynamometer is not able to measure the real power at the wheels, it is physically impossible with this kind of instrument.
Dynos which are not able to measure the shaft power but, anyway, they give the power at the wheels, are only delivering extremely inaccurate numbers. They are obtained without properly considering test conditions’ variation. For example, think that it is sufficient to differently tighten the anchorage belts of the vehicle, or a different pressure of the tires, or a different temperature between a test and another, to significantly alter the power at the wheel. The only power to trust in order to have precise data, and to make comparisons, it’s the engine shaft power. Bapro has obtained many acknowledgments by its prestigious customers, in terms of absolute accuracy in the measurement of the shaft power, through comparisons made with engine test benches, in climatic controlled cells too. This experience has been grown in the last 10 years developing specific chassis dynamometers to supply different and huge automotive brands, and their Research and Development departments.

Are there power limits?

Technical specs of each product show the declared maximum horsepower, but it must be clear that this power level is referred to static tests, such as stopping the vehicle at constant speed or mapping. Performance tested in dynamic tests, so with the aim of measuring power and torque curves, actually have higher maximum power levels. Just have a look at the tests done by our customers and published on the site. The first limit of a dynamometer is not braking performance, but the grip offered by the rollers. In fact, before reaching the limit of breakable torque, we encounter the problem of slippage. This situation does not exist on Bapro, thanks to the peculiar characteristics of our rollers. Test benches declaring thousands of horsepower for each axis, are doing it simply referring to an inertial test and not braked, with all the limitations listed in paragraphs 1 and 2 of this page.

Is it possible to upgrade from 2wd to 4wd?

Bapro chassis dynamometers are designed according to the concept of modularity. This allows customers to buy the 2wd (BPA-2R) and, after that, upgrade it to the 4wd (BPA-4R) by simply adding a second bench, with the wheelbase adjustment system in between. In this way you can start with a lower investment and then, without “throwing away” anything, you can buy the necessary components to go with the 4wd version and start to test all cars. The concept of modularity is also inside the type of installation. In fact, you can install the dyno above-floor or put it in a pit without the need of additional accessories.

Why bapro dyno for motorbikes (mod. bpm-2rs) has 2 rollers?

Bringing the concept of cars’ dyno to bikes’ dyno, it is clear that, in order to measure high power levels by means of eddy current brake, we need maximum grip, so maximum rollers surface. In this sense, the surface offered by a single roller is not sufficient if we have to deal with very powerful engine or very high torque engine (ex. Harley, Ducati and twins in general). Bapro chassis dynamometer is available in both single roller (BPM-1R) and double-rollers version (BPM-2R). In this case too the modular design allows customers to start with single-roller version, particularly suitable for those mainly working on scooters or motorcycles with medium/low power. After, when the customer expands to higher performance motorbikes and/or race bikes, he can add the second roller. Thanks to lightened rollers, BPM-2R has all the advantages delivered by extremely high grip (which you cannot get on any other dyno test bench!). This allows you to have no limits of maximum power but also to test with accuracy low/very low powered vehicles (i.e. small electric scooters).

Is a specific training necessary?

Bapro software is extremely easy and user friendly, so you don’t need a training course, even if a full course in Italy lead by our technicians is included in the installation of the instrument. The software version supplied in the standard configuration of the rolling road is complete and allows you to make all possible tests, with quick and simple steps. All functions of the bench can be used by remote control so you need only one operator. The manual coming with the product and the assistance of our technicians and engineers help you to learn very quickly to use the tool, and to make the most of it fully, even without a training course.
BAPRO provide with all dynos a fully working version of chassis dynamometer’s software, no ADD-ONS or extra costs!

Is a dedicated pc necessary?

The electronics control of Bapro chassis dynamometers is integrated into the dyno test product, so you do not need a dedicated computer. Moreover, any kind of hardware installation inside the PC isn’t required. A commercial computer is enough. In a few minutes you’ll install Bapro software on it and start to use your Bapro chassis dynamometer.

Why double rollers dynamometers are better than single rollers.

Single rollers chassis dynamometers sometimes are said to be able to simulate a flat surface of a road better than two rollers. Unfortunately, to do that, a diameter of at least 800 mm is needed, otherwise there won’t be enough flat surface at the top to provide enough traction in order to collect all the power of the car.

That’s why all single rollers dynos have big rollers, but it’s never enough!

To be specific, the surface of contact between tyre and roll is smaller in size than on the road and it is about 1/3 of the area available in double rollers dynos. 

This is caused by having only one area of contact at the top of the roll (as we can image it’s not flat like on the road, thus reducing the surface further).
Less surface = less traction = lower maximum power of dyno. 

To conclude, it is much more probable that the car will spin tires instead of transmitting all its energy to the rollers to measure it. 

Double rollers dynos simply solve this problem doubling the number of rollers in contact with the tyres.

Moreover, a big roller has the consequence to have big inertia and this is bad for accuracy (bigger rollers = bigger inertia for same roll weight = not correct and repeatable measurements, see the first FAQ regarding inertial dynos).

Double rollers dynos don’t have this issue since their rollers have low inertia.

One more thing, for all single rollers dynamometers a very deep pit is needed, since they have very large rollers which cause the chassis to be very high (for example 800 mm deep). Bapro double rollers dynamometers instead require a pit only 450 mm deep.

Last but not least, if you look into YouTube and search for “dyno accidents”, you are likely to find accidents of cars on single rollers dynos. As we can imagine, a car is in a not stable position on the top of the roll and belts’ breakages or even not enough belt tension can cause the car to fall down from the dyno.

This potential risk is a lot less likely to happen on a double rollers dyno, since the car is in a stable position between the two rollers, so there is no way for it to fall.