I have never used one of these but various discussions of this type supercharger on other websites point out that the airflow on these is too low for engines of decent size. Maybe you can get some increased power out of a small ricer, but the LS probably won't get any boost from this. I bet the only hp increase is due to maybe a less restrictive air filter intake. One other factor in addition to CFM is "at what PSI", Seems like none of these electric chargers list that very important spec. Maybe becuase they can't handle the PSI required to make power.
I bet at high RPM the LS draws a lot more than 250 cfm. Heck a small street V8 can easily pull 600 cfm and up depending on the engine etc. There is a formula, last I read in an old Holley carb book that calculated how much a nasturally aspirated engine would pull.
Just some slightly educated calculating based upon the voltage and current and reading for long ago, I would say the motor on the is charger is about a 24 watt motor. That ain't much. To get the psi required for real supercharging, some designs like the Roots and the Paxton types pull power from the engine crankshaft, and in some cases they pull a LOT of power to get the boost needed.
The consensus of the two or three automotive websites I visit is that these don't has enough power to build the PSI needed for real power.
Just my opinion,
Jim Henderson
