The big difference is this...a turbocharger builds boost EXPONENTIALLY, where a supercharger builds boost based strictly on gearing and rpm. So, a turbo will actually spool faster than a supercharger. A supercharger that makes 15psi boost, will usually hit that max boost at or near redline, while a turbo making 15psi boost, will hit that with rpm to spare. So, you can gradually climb to 15psi with a supercharger, or you can afford a few hundred rpm's of lag and hit that 15psi at around 4k rpm's, instead of 6200rpms or whatever you redline at. I've had both. Had a vortech s/c on my 95 Dakota with a built 318, running 8psi, and I had an 88 mustang coupe with a 2.3l and a t3/t4 hybrid turbo that ran 23psi. My dakota made 8psi right at my shift point of 6000rpm cause the blower was geared for that, while the turbo on my stang hit 23psi at around 4400rpms and stayed there till shift point of 6800rpm. Big difference. Pretty much the same power between the two, and taking into account the weight difference, there was a 2.7 sec. difference between the two at the track. I think if some ricer had not hit my truck, and I could have put on my twin turbo kit for it, it would have ran 8psi but made up for at least .8 tenths or maybe a full second at the track.

 

i found this the other day. it looks really f'n cool to me. partly because it actually makes use out of the non functional side scoops.