Wow, I could literally write a book on this one but I'll to keep it brief and address the highlights as I see them.
For the Street:
· A Rotrex typically runs better IAT's
· A Rotrex is better for under the hood temps
o You can typically push it harder, faster, longer than a turbo at a comparable power level
· It typically creates a nice linear power band that is excellent for drivability
o It behaves itself enough for grandma to drive unless she puts it to the floor
o Its linear power band is fluid and increases until redline
o No severe excess of torque in the mid range then a gradual decline in output as with a large single turbo
o A Rotrex is going to enhance the natural characteristics of the motor
§ In fact, the Rotrex will make it feel quite simply, like you bolted a much larger motor in place
· The Rotrex has No lag whatsoever, throttle response is instant and almost always improved
o The Rotrex is always flowing more air then the motor needs so it ALWAYS has power on tap
o A car with a Rotrex always feels like it is ready to pounce
· The fun factor is through the roof for all of the above
What do I mean by this last comment?
The torque delivery of the Rotrex is linear and increases until redline. This equates to the feeling of sitting in a rocket that gets faster and faster and faster until you let off the gas. A turbo has a different feel. A turbo setup when matched HP for HP to a Rotrex making large numbers on a motor will typically hit incredibly hard at its boost threshold then taper off to redline.
That said, the Rotrex is not going to provide an ungodly kick in the pants. Instead, it is nice and smooth and predictable.
If you like controlled fury, the Rotrex is for you. If you like a wild *** kick in the pants and hanging on to life by a thread, maybe the turbo is better.
IMHO ->
Street, Twisties, The Dragon - I say Rotrex
Dragstrip - I say turbo and some monster tires to keep that torque to the ground!
There is a lot more to this discussion as you could also go off into electronic boost control, WI, etc. The answer is Yes, you could build a turbo to match the characteristics of a Rotrex AND have the ability to turn up the boost at will. However, at what relative cost and level of complexity?
It really all depends on what you want out of it and your application. Many people think it is about nothing but low end torque. I typically am on that boat, but there is such a thing as too much. Just ask the guys who can never seem to find a tire wide enough to keep their rubber from melting off the rim
To me, the Rotrex is the perfect compromise and fits the largest number of "wants" on my well educated wish list.