Essentially it's a test rig that checks engine performance. You'll often hear it described as a �ebrake', this is because of the way it measures engine performance by calculating the load necessary to keep the engine stable at any set speed. The engine is bolted securely in a cradle and then connected to the dyno, which balances the engine's power by applying the same force in the opposite direction.

As soon as an engine's been built, it's tested immediately. This is normally a week before the complete Subaru Impreza WRC 2004 rally car is finished and taken to a car track for it's final test. After an event, an engine will be stripped and rebuilt, or it may be used as a test engine.

We're basically making sure that the engine achieves the targeted performance. Each engine will be tested using various speeds and loads for one hour ten minutes to bed it and seat the components. It then undergoes a power curve test when it's run at every speed from 3,000 to 7,500rpm, moving up in steps of 250rpm (revolutions per minute) every ten seconds.
The power curve test allows us to assess the engine's power as well as providing an opportunity to carry out an engine health check. All aspects are monitored, including boost pressure and temperature, turbo speed, exhaust pressure and temperature, water and oil temperature, oil pressure, fuel pressure, the air / fuel ratio, ignition and fuel settings. Computers feed back visual information during the test, which is printed as graphs after the test is complete. We use these to check for any inconsistencies. Rev limiters are also set and engine maps configured.

It would be far more difficult to measure its performance output in the car. You can't stabilise conditions such as air temperature, humidity and oil temperature like you can in the dyno cell. Using a dyno you can hold the engine at one speed for a long time in consistent and predictable conditions.

Absolutely. Using a large industrial air conditioning unit, we can set air intake temperature and humidity to whatever we want and can regulate the environment to reproduce realistic climate conditions at forthcoming events. That might be the heat of Greece or the freezing conditions of Sweden. But, normally we run the engines at the same constant, fixed temperature so they can be compared.

That's for safety reasons. The glass is triple layer, bulletproof material. When the engine's running the turbo can be spinning at 160,000rpm and if anything unusual happened, such as a part of the engine coming loose, you want to make sure everyone is 100 per cent protected.

Only when the engine is off or idling. Because of the reasons mentioned above, you're not allowed to enter the dyno cell when the engine is running and have to remain behind the glass.

After the engine is taken off the dyno, it goes through a post dyno inspection (PDI) where the oil filter's changed, and the timing belt and compression are checked. Next we have a look inside the cylinders (through the spark plug hole) using a special type of microscope to make sure everything's okay. Then the wiring harness will be tidied up, all connections checked and the engine is ready for installation.