Looking at a 92.

It's a 1991 with 139,000 miles. It appears to be in very good condition, although I haven't driven it yet. The asking price is 2,500. It's a v6 3.8L with a supercharger.

My questions are, how long do these engines generally go for, what are their most common problems, and how much hp do these stock supercharged 3.8L's push, and what kind of 1/4 times do they run?

Reliability? Well, their high maintnence. And it helps to hace some back ground knowledge on these cars. The biggest issue with the 3.8 (NA and SC'd) are bad head gaskets. If they were changed recently, you should have no worries. HP was 215 untill 94, which got a few extra HP. 1/4 times are high 14's low 15's, depnding on various factors.

Ahh only 215? Must be a pretty weak supercharger.

uh. 215 was "decent" back in the early 90's late 80's. Its high point was 315 TORQUE. Remember, "Torque wins races, horsepower sells" Lets run a few numbers...

HP/TQ:
1994 Mustang GT: 215/285
1990 Nissan 300ZX: 221/298
1996 Lexus SC400: 245/258
1996 Lotus Elise: 120/122
1995 Mazda RX7: 255/216
1992 Porsche 968: 235/225
1989 Toyota Supra Turbo: 232/254
1996 MR2 Turbo: 199/200

And with just a pulley and chip, the S/C can make 245 HP..then add on exhaust, and gears!

Its a lot better then you think! ,but still not a V8!

$2500 is very high for a 91 with that many miles on an original engine. I got my 93 for $2500 and it came with a donor engine with 64K on it. $1500 would be more like it for that car.

With that many miles, I'd be looking into swapping a new engine if I were you.