Shirley said:
Thanks for the info on the rear end but my main concern is whether to go supercharged or n/a which would be the cheaper option, and which would be more practical? Second, 4.10's are too much for an auto with a supercharger, I thought the AOD needed all the help it can get.
I suppose the real question is how fast do you want to go? Are you looking for a low 12 second car or just something to suprise the import that pulls up next to you and rev's his engine? Start out conservative and add more goodies as opportunity and budget permit.
Screw or Roots superchargers fall into the category of postive displacement superchargers. They produce most of their boost in the low to mid-range RPM band. Using 4.10's may give you a lot of kick at low speeds, but it may be too much torque to sucessfully communicate to the ground without some major chassis & suspension work. That translates into a car that spins and smokes the tires more than it goes. Kind of like driving 400 HP in the rain all the time - scary & slippery.
Don't forget to take into account that the 4.10's will increase the RPM's that drink gas and can raise the noise level up to the point that you avoid long trips. Mustang exhaust systems are famous for the drone that starts at 1700 RPM's and doesn't taper off until you get above 2300 RPM. Most of the time you have to turn the radio amost to the pain level and shouting can become a habit.
Too loose a converter will be mismatch for a postive displacement supercharger, since it has lots of low end torque and boost drops off as RPM's reach the upper ranges.
My personal choice would be an H/C/I combination with some good aluminum heads. That way you can add pressurized induction at a later time and get more power with less boost. Stay away from heads with large port volumes and monster valves for a Daily Driver - you'll lose too much low end power. In like manner, avoid wild cams - the lopey idle may sound cool, but it kills the low end as well.
Once you do commit to an H/C/I package, you'll need to make some decisions about the trans and converter. Keep you future plans in mind when you make your choices. Too loose on the converter and you take away the streetablity. Too tight on the converter and you can't get the RPM's up to get going quickly.