Dyno Differences and Understandings

It’s not everyday you get a dyno. Not all dynos are created equal and not all dynos read the same. After a little bit of research we decided on a Dynotech, a widely recognized chassis dynamometer. Dynotech uses a large drum of mass to measure the amount of force a car can exert on it. It takes this information and calculates the horsepower and torque of the vehicle. In order to do this calculation it also needs a tach signal. The reason for this is that the calculation is a relationship at given rpms. (HP = Torque x RPM ÷ 5252)

The true torque of a motor can only be seen at the engine as torque is a relationship of distance from the center line of the crankshaft. If the transmission was truly 1:1 you could measure this at the wheels but since most transmissions have no gears that are exactly 1:1, we chose a gear that is close to 1:1. This gear is generally 3rd or 4th. As an example the mazdaspeed 3 uses gearing of 1st 3.21, 2nd 1.91, 3rd 1.37, 4th 1.03, 5th 0.95, 6th 0.79. As you can see 4th gear is the closest to 1:1.


The dyno dynamics dyno we chose uses an electromagnetic force to measure power. This makes the unit smaller and more portable. It also makes the dyno able to change loads. You can literally apply a certain load and very the rpms or very the load and keep the same rpm. This is great for load based tuning and limits the need for a “Road Tune” as you can create real life conditions on a dyno.

The downfall of the dyno dynamics is that it is often called a heart breaker dyno. The actual reported numbers are some of the lowest numbers out of any dyno. This fact makes it important to understand that increases in power should always be measured in percentages. That way when you compare numbers, the percentage gained should be about the same while the increase in actual value might be less. You can see this below in the graphs.

Dyno Chart

The lower powers are with a stock Mazdaspeed3 and the higher values are with the exact same mods. The left dynojet graph shows a 30hp difference at one point . This is about a 14% increase in power. If you dyno the same modifications on the dyno dynamics and you see about 25hp difference which is also a 14% difference. Even though the dynos show a 5hp peak difference we know the modifications increased the same amount of power. This is shown in the percentage difference. Horsepower numbers can be shown to be a higher value but the percentage should always be similar. A point not missed when we recently dyno’ed a mazdaspeed3 that made almost 700whp (~+206%) on a dynojet but 580whp (~+204%) on our dyno dynamics. The percentage change was the same but peak difference was massive.

With the power of our new dyno literally at our fingertips, we have complete control over the test and the demands placed on the vehicle. Utilizing the dynotech software will allow us to evaluate the entire drive-train condition for the purpose of all-out performance development. Stay tuned for more rock solid, well engineered products that will take your Mazda to the next level.


3 Replies to “Dyno Differences and Understandings”

  1. the 708 whp was with an open dump exhaust, the 580 was with a full cobb exhaust. Not quite the same setup. I think they hit 640whp with the full exhaust on a dynojet.

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