We’ve recently been asked why we display our power gains as a percentage rather than actual horsepower and torque values. The most straightforward answer is – simplicity. There are many variables when it comes to obtaining a power figure. Things like tire pressure, dynamometer brand, type, and model, how a car is strapped down, the weather, and more can all impact the final measurement of power. A change in any of these variables can swing power figures by a significant amount on a car that has remained, otherwise, exactly the same.
In order to arrive at a percentage gain, we take the average of three pulls before and after a change. Whether this change be a small tweak to the tune, changing out a hard part, or experimenting with dyno setup you will likely see a change, or delta in the output. We then take that change and calculate it into a percentage gained or lost from the initial value. As an example (seen in the video): we take three dyno pulls of a completely stock car and average them. Next, we install our Big SF Intake and flash that car with the appropriate map file. After that, three more dyno pulls are made from which we calculate an average. We can next take the delta from the two averages and divide it into the original power numbers to arrive at our percentage gain. It’s as simple as that!
If you’re looking for a bit more clarity when it comes to dyno results, check out our recent COBB Blog article titled Interpreting Dyno Results.