What's the average driving time from Manoa area to downtown Honolulu during peak and off peak hours?

It depends on whether you are talking about near UH or at the back of Manoa Valley. From UH to downtown, off peak, 10 minutes. Peak traffic 20 minutes. Add a stalled car, an accident, heck, even some rain, & you can easily double that number. You can add 10 minutes to the times I quoted if you are going to the back of the valley.