You can use TW University's power potential data. Power potential is a real-world measurement (called ACOR in tennis physics terms) of how much energy put into a racquet, as swingspeed and ball speed, come back out as shot speed.
Compare racquet power potentials:
http://twu.tennis-warehouse.com/cgi-bin/comparepower.cgi
Compare racquet shot speeds:
http://twu.tennis-warehouse.com/cgi-bin/comparespeed.cgi
Compare racquet 'sweet zone' size:
http://twu.tennis-warehouse.com/learning_center/contours.html
Of course, these tools tell you how powerful one racquet is compared to another - provided you can swing the racquets at the same speed. Racquets with higher swingweight are more powerful, provided you can swing them as fast as a tweener or granny stick.
This tool,
http://twu.tennis-warehouse.com/cgi-bin/trajectory_maker.cgi
allows you to compare shot trajectories of two racquets, either the same or different, and change each stroke parameter, i.e. swingspeed, swing angle, etc. It's interesting to see that spin is (almost) entirely dependent on swingspeed, while depth is increased by more powerful racquets (if you can swing them as fast, and if you can't you'll lose spin).
Finally, a racquet comparison tool of important specs and power potential data:
http://twu.tennis-warehouse.com/cgi-bin/racquetmatch.cgi
I played around with these tools a lot and found that different racquets don't make much of a difference, really. Which is why there's a demo program, and guys like the esteemed NoBadMojo who intone: "if you know your ideal swingweight..."
One interesting thing is to check out this tool,
http://twu.tennis-warehouse.com/learning_center/specsandspeed.html
which lays out racquet power potential and shot speed cross referenced to different specs. Swingweight is the most important to power, and the limiting factor - if it's too high for you you can't swing it as fast.
If you set up this tool for swingweight you can then go down the list and find the most powerful racquets available for a given swingweight or swingweight range. Most of the standouts are oversize frames, but there are some notable exceptions. The DNX 10 mid for example, and the DNX 9, are both disproportionately powerful, given their specs. The PB 10 is not so.