Dyno types

Please correct or add as necessary - as I understand it, there are two types of dynamometer types that are typically used for tuning an EFI system.

Brake type allows the application of a load at various speeds and allows to tune for knock, AFR, etc.

Inertia style is really used to determine maximum horsepower/torque and can not be easily used to tune mid-range performance.

Is this a correct way to state the difference between the two? Can an inertia style be used as a tuning tool at lower rpm's?

Thanks for any help/explanation you can offer

You've pretty well nailed it. The inertia dyno has no power absorber module and as such is only useful for WOT ramp runs - Great for a drag car but of limited use for most applications. A load bearing dyno uses a power absorber module which is capable of applying a variable load to the wheels which allows steady state tuning as well as ramp runs with variable ramp rates.

An inertia dyno gives you no real time feedback of engine torque and combined with the fact it doesn't include a power absorber module means that it is of very limited use for part throttle and midrange tuning.