Which type of dyno can I trust?

First of all, the dyno must be calibrated in order to give correct measurements.

A real engine dyno is normally a correct tool, but it is not always possible to take out the engine in order to have your power and torque measured.

A chassis dyno can also do the job, but nowadays it is very important for the newer car to let it run on a 4WD dyno where the 4 wheels turn always at the same speed, even if you have a 2WD FWD or RWD car, such as on our Superflow SF880E. The reason for this is that speed is now also a very important entry for the ECU.  If the ECU misses the speed signal, it often goes in another part of the program than normal and power measurement is not correct.

Even when traction control is disabled and all the fuses are taken out from ABS etc... , some cars will still go in another part of the program and don't give full power. The only way to maybe measure correctly on a 2WD dyno or a not 4 wheel driven 4WD dyno, is by going first to the official dealer and have him put the dyno mode on the car. If this is not done, the power measurement on this type of dyno's is not correct.

Another point is also that chassis dyno's measure wheel power.  Only sophisticated dyno's have a program to measure transmission loss correctly. If this is done correctly, than wheel power + transmission loss = engine power.

Some tuners add a fixed percentage to the wheel power to calculate the engine power. This is not correct, because it differs from car to car. The only way to know the real transmission loss is to measure them in the same gear as the wheel power measurement.

Comparing wheel power from one dyno to another is not possible for the following reasons : the transmission loss are influenced by the tyre pressure and how the car is fixed on the dyno. Lower tyre pressure give more loss, a firmer fixed car also gives more loss. The only way is to measure exactly the transmission loss each time you want to measure the wheel power again.


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