Pros and cons of buying an used dyno
As new, modern modular rolling roads may be expensive, especially at the beginning of a new business, used dynos for sale are listed in various internet pages. There are some better and worse developed dynamometers, but in most cases the whole idea of chassis dyno is common – a steel crate with rollers, sometimes twin-rollers. 4Wd (4x4) dynos may have front axle connected to rear with the belt or drive shaft, but most older dynos have no front-to-rear connection and are intended to stabilize and equalize roller speeds with electromagnetic brakes.
There is nothing wrong with buying such old machinery, especially if the price is good. But there are some important things that must be considered for future use:
- what is the surface of rollers? Flat steel surface will be slippy, curled (corrugated) rolls are better.
- what are the possibilities to install new sensors to enable usage of new, modern dyno software?
- when we consider one axle dyno – will this be expandable to 4wd dyno? Old dynos are not modular, usually to convert it to 4wd you need to consider really huge costs of work and material
- if 4wd used dyno is taken into consideration – it is extremely important to have front-to-rear connection within, or to be able to add it. Modern cars, even one-axle driven need all four wheels to rotate to avoid traction control failures, power reduction etc.
- what is the weight of rollers? Heavier ones are better. Also thin-wall rollers cannot be curled (corrugated) in the future.
- does the dyno have pneumatic ramp to lock rollers and lift the car?
- if the dyno is equipped with electromagnetic brakes – what is the voltage and current needed to control them? As there are many different types of eddy current brakes, not all modern dyno controllers will be capable to be attached to them.
- what type and accuracy is the force sensor (extensometer) at electromagnetic brake? Again, it is important to have extensometer compatible with the new control system – or separate controller will be needed – that increases the total cost of the project.