Understanding Dyno Numbers

First of all let’s begin by saying not all dyno’s are created equal!

All dyno’s serve a purpose and it’s your job as a consumer to do your homework to find the dynamometer that will help you achieve your goals. If you are just looking for the highest possible number and have no interest in using the gathered data to ensure your package is setup correctly, then an inertia type dyno is the one for you. These are common at shows where a dyno shootout is being held. A 2wd vehicle with a manual transmission will typically incur a 15-17% loss in power from the BHP (flywheel horsepower).

If you are looking to use the data for tuning purposes then you definitely want to use a “loaded” dyno or one that has an Eddie Current Brake on the side of the rollers. It looks very similar to a massive brake rotor with a magnetic “caliper” so to speak that induces a load to simulate the vehicle being driven on the street. With today’s computer controlled vehicles that setup spark tables based from the load being placed on the drive-train, it is imperative to have this setup when dialing in a high performance application. A 2wd vehicle with a manual transmission will typically incur a 27% loss in power from the BHP. Although these numbers will obviously be lower over all they are the most accurate. This IS why all aftermarket manufacturers use an inertia style dyno for testing horsepower gains with their products and that is what everyone reads about in magazines. Lets face it, they are out there trying to sell products and they need to have the highest possible number to move their products…whether or not that number is real, it sells products and we can thank the consumers for not holding the manufacturers to their advertising word.

If I could offer a piece of advice, get your setup tuned correctly on a loaded dyno then take it to an inertia style for the “almighty” hp # and you will see that every time, tune for tune the vehicle tuned on a loaded dyno will make more horsepower and torque and have the better driveability than one tuned on an inertia dyno. This holds true because when steady state tuning a computer controlled vehicle you are able to load the vehicle and dial in the trims with pinpoint accuracy to gain the best driveability (smoothness throughout the rpm range) and the car can be loaded to reach the higher spark levels as well so no worries about spark knock or worse…holding piston pieces in your hands after a test drive.