Why do Dyno’s read differently?

There are two types of Dynamometers, Load Bearing (you can simulate putting the car under a load, i.e. going up hills, holding a specific RPM or Speed, etc.) and Inertia (the Dynamometers rollers are moved by the torque of the wheels). Load bearing Dynos will have lower output power numbers due to the load in most situations. Other major factors are the parasitic information in the Dynamometers computer system, Temperature in the room, Intake Air Temperature, Humidity, Barometric Pressure (different altitudes), SAE correction factor, and what gear the car was tested in.

When FLI first installed our Dyno, we retrieved multiply shops parasitic information with the same Mustang AWD SE Dyno. FLI did install Mustangs’ Weather Station so we can measure and log Tempature, Humidity and Barometric Pressure in the Dyno room. This is key because it really does matter when comparing Dyno numbers. Here are some different tests that FLI performed to show this point:


Here is an example of 20 degrees of Temperature difference in the Dyno room:
Yes that is correct! 40 HP and 43 TQ. to the wheels!

http://i15.photobucket.com/albums/a388/FLIWRX/02_WRX_Cold_vs_Hot_Temp_Test.gif?t=1194477367

Here is an example of two 2006 Stock STI’s:
The first one is tested at 69 degrees with 58% Humidity with stock boost levels.


http://i15.photobucket.com/albums/a388/FLIWRX/06_STI_Stock69degrees.gif?t=1194477439

Here is a stock 2006 STI with 75 degrees with 45% Humidity and stock boost levels:

http://i15.photobucket.com/albums/a388/FLIWRX/06STIStocktempis75degreeswith45humi.jpg?t=11944774 05

As you can see there is 1 horsepower and 10 torque differences between the two. This is because of the difference of 6 degrees and 13% humidity in the Dyno room.

Summary, next time you talk numbers with your friends make sure you get the Tempature, Humidity, Boost levels, gear tested in and Barometric Pressure!



Miles
Fine Line Imports
www.finelineimports.net