Dyno

[chopstick1981]

I am wondering if a dyno is performed(at the wheels) where are the hp. and tq. values represented at? because torque values will be different depending on which gear the readings are taken in because of the different gear ratios, plus the ring-pinion ratio. I guess the phrase "dyno at the wheels" has me thrown off. because if it is really reading power "at the wheels" the gear ratios will then magnify the power read by the machine, and then it would be a different set of hp. and tq. values for each gear. Does a dyno computer factor out these ratios?

[johnnyBgood]

Different dyno's operate in different ways. I am familiar with the dynapack dyno.

The dyno runs are standardized. 4th gear for manual transmissions and 3rd for automatic, usually.
Also, the gear ratio needs to be known and thru various tests, the computer comes up with the ratio. Then your car is run, usually 3 times for accurate measurement.

The dynapack dyno gives you your whp, wtq (which needs to be divided by the torque ratio, different for each car) and flywheel torque and horsepower. For example, my car dynoed 555wtq. But that needs to be divided by the tq ratio, which is 4.043 which gives me 137.27wtq.