Really nifty study carried out by ORNL to clarify how much energy is lost in the Prius II drivetrain/transmission.

I thought the following two graphs were the most informative (click on the images to see a magnified version. Note that the Y axis is watts wasted--

By component:
As oil Temperature Increases

 

I wonder how the IMA system compares for efficiency, especially with the CVT?

 

Hi,

Answers for Honda hybrid hybrid performance questions are not often found in the Prius discussion group. Regardless, you could find the answer easily enough. The overall approach is:

1) Remove the engine (assumes a powered dynamo)
2) Make sure the Honda IMA motor shaft can rotate (you may need bearing support)
3) Make sure the lubrication pumps are connected or rig up a substitute
4) Make sure other fluid channels are sealed and setup substitute fluid loops
5) Connect the rear wheels to a dynometer (contact local hot rod shops)

Have the dynomo operator sweep different speeds and plot the Honda IMA power loss as a function of MPH. It is a good idea to rig up a lubricant heater and temperature probes to monitor the effects of temperatures. Also measure the generated EMF from the Honda IMA motor.

BTW, there is a Honda discussion group where IMA experts for Honda hybrids might be found.

GOOD LUCK!

Bob Wilson