How to read a dyno chart

How to read a CPL Racing dyno chart

Further down the page is an example of a typical dyno chart showing HP from the same car before and after modifications.  We publish this type of graph to help customers understand the true performance increases gained by modifications.

When customers make an enquiry, they usually make reference to peak power figures ONLY.  Although relevant, the peak power figure is just one element of what is important when considering how effective a power upgrade is.  In order to explain this better, we have shown an anotated sample graph below.

Firstly take a look at the vertical scales, in this instance both vertical scales read HP. (This means wheel horse power as read by the dyno).  You can see that each large block represents 30 HP, which is sub-divided into 5 smaller blocks which each represent 6 HP.

Secondly, look along the horizontal scale and note that each large block represents 1000 rpm, with each smaller block within representing 200 rpm.  In this example we are looking for HP gains at 5500 rpm and 7500 rpm.  You can clearly see that at 5500 rpm there is a HP gain of 66, and at 7500 rpm a HP gain of 72.  Additional things to note about this comparison:

1. There are power gains at every point in the rev range

2. Above 8400 rpm there is power that did not exist before the modifications. (In fact you can see that the power was still rising but the rpm limit had been set to 8800rpm for safety)

3. The higher of the two power lines is highly linear after modifications, without the lumps or bumps which were present before modification.

4. The graph below shows a meaningful comparison as it is comparing the same car on the same dyno before and after modification. There are large variations between the readings of various makes of dyno, so in most instances you will not get a realistic comparision if you compare a power reading/graph from one make of dyno to the power reading/graph from another.