What are the advantages and disadvantades of each.

 

OK here goes... Im not an expert here so feel free to correct me anyone.

S/C
Pros:
-Less heat generated
-Boost according to RPM... no spooling down, or turbo lag
-No exhaust plumbing required
-Good low end boost

Cons:
-Takes power from engine to achieve boost
-Lower high end boost compared to turbos
-Belt slipage

Turbo
Pros:
-Obtains boost from exhaust, making it more efficent, not taking much if any power away from engine.
-Higher peak boost

Cons:
-Generates much more heat than S/C
-Requires extensive exhaust plumbing, waste gates, blow off valves, etc.
-Turbo lag, not too much of a problem in higher displacment engines though
-Not as much low end boost as s/c, requires spooling up

Fell free to add to what Ive said, as I probably missed some things... all I could think of at the moment!

 

you forgot price differences. turbos for our cars need to be made, but there are several supercharger kits for sale. I think the 142 is about $1500 and can give you 100-200hp depending on what you have to start with.

 

I agree with most of what 88 WS6 mentioned, except that in not all cases a supercharger makes more boost down low, definitely not the case in a paxton or vortech (not root-based). The roots does produce good boost down low because it is positive displacement. You can also get as much boost as a turbo, but then the belt slippage problem arises.

I would say that a good comparison would be between a Procharged I/C car and one with a single turbo I/C with the same engine setup. Obviously the PC is a bolt-on but the belts become a limiting factor, it would be cheaper to do $ wise. The turbo plumbing would have to be fabricated and would be just as durable, but without the belts. I would say at 15psi boost on a typical 350 the turbo may have a 5-10% power advantage. I assume both motors are tuned with DFI or something programmable.

But when you go to higher boost levels in both the SC and Turbo you sacrifice bottom end to gain more top end. But a properly chosen turbo has better efficiency than a typical race supercharger does, so it makes the same boost without as much heat.

If you go twin turbo (two smaller turbos with flow the same as a typical big turbo), some interesting things happen: first, it becomes more of a PITA to plumb it. Second, you get a low more bottom end because the turbos spool up quicker than 1 big one. If you run the special ceramic turbos, they spool up even faster. The torque advantage is mostly mid range where the motor could use it (compared to all top end with a single).

I think the average guy would want to spend the $3000 for a bolt-on supercharger because it is easy to install and requires no fabrication (or internal motor work), but gives up some power. A serious HP head would sort through all the problems and go for a single or twin turbo (most Stang racers do nowadays) that has the option to easily upgrade to rediculously high HP levels (I'm talking 750hp and up for a streetable 350). A full-on race SBC could probably put out 1500hp and last more than a few hundred miles (compared to a NOS race SBC) and occasionally be driven on the street. Remember that PHR twin turbo Vette?

*** bless the gods of forced induction