DYNO Experiment - Why power can be down on a dyno...

We did a little experiment today. A while back we took a bog standard 2001 V70 T5 manual, and remapped it with RICA software. Then the car was driven for a while for the adaption to adjust. Here is how the car runs on the road, after several days of driving -

3000 rpm - 1.0 bar
4000 rpm - 1.0 bar
4500 rpm - 1.1 bar
5000 rpm - 1.2 bar
5500 rpm - 1.25 bar
6000 rpm - 1.2 bar
6500 rpm - 1.2 bar
7000 rpm - 1.2 bar

Today we took the car to an independent dyno, and on the dyno it performed like this -

3000 rpm - 1.0 bar
4000 rpm - 1.0 bar
5000 rpm - 1.0 bar
6000 rpm - 1.0 bar
7000 rpm - 1.0 bar

Max power was 250 bhp @ wheels at 6000 rpm @ 1.0 bar. What is quite clear from todays testing is that under the adverse dyno conditions, the ECU refused to allow the boost to run above 1.0 bar.

When driven on the road straight after, the boost was back to 1.2 bar. The reason for this is simple - lack of proper air flow on the dyno due to the small fan, so the various sensor readings were telling the ECU to lower the boost. It's a good demonstration to show why a car can easily be down on power on the dyno if the air flow from the fan is inadequate.

Adam.

ps. This is not some post for making excuses for low power figures! It's a genuine attempt to let those who are interested see how dyno conditions will determine engine performance, compared with on-the-road conditions. More experiments to come...