[mike@x-ph.com]

Hello,
Very interesting and simple video on Dynos. Most of the info given are basic but very important.

Not all dynamometers are created equal. This Episode of COBB U should clear up any confusion related to interpreting dyno results, understanding percentage gains, and how to compare data across differing dynos.

[ovekvam]

Very basic video. They don't really explain the difference between dyno types. They also miss out on explaining about the torque measurement, which a lot of people don't seem to understand. The torque number you get out of the dyno, is a very strange figure. It is not measured at the wheels, but calculated from engine speed and power, to give an estimate of what torque you have on the engine flywheel. If it was the actual wheel torque, the figure would be significantly higher, and people would be even more confused.

They also missed out the entire topic of drivetrain loss. Dynos will mostly measure power on the wheels. Some will give you that figure, and some will try to estimate the drivetrain loss, and give you a flywheel figure. These estimates are often way off, since the loss can't be measured accurately. The drivetrain loss is a lot smaller when you use a dyno connected directly to the hubs, since the rolling resistance is taken out of the equation. With cars strapped tightly down, that is a big factor.

[ttimbo]

The critical value of dynos, IMHO, is for measuring changes to one's car through tuning and modifications. That is, using the same dyno and with the same operator, you can compare the before and after output data, as well as changes to measures such as AFR and EGTs. Comparing outputs of cars from different dynos is pretty much pointless.