20bb can cost upwards of 15k to install. and thats w.o a rebuild... most likely you wont be able to run twin turbos unless you remove all the solenoid shit.. single turbo is money too...custom manifold plus nice size turbo around 5k... plus intercooler piping, intercooler, radiator, subframe, fuel, and most importantly computer.... Its a big ass mission and I doubt its even comparable to a simple ass v8 swap...

either way your gona have to make a subframe to fit the larger motor. with custom plumbing. 20B will cost about $3500.
most of either swap would be custom fabrication

3500 will barely get you the motor... let alone a rebuild... subframes are expensive but thats not the whole cost of the motor... atleast runnin a carbed v8 you dont need a computer... regardless I would have to say that a 20b in a fd is alot more costly than puttin a v8 motor...

Parts total will cost 10k for the 20B. You can get Alamo Rotary to do it for 20k or do it yourself for the 10k.
http://66.69.208.196/tfatf.jpg

most 20Bs are $3-4K thats about the same price as a decent SB crate motor (around 350hp). with both motors you will need to fabricate a subfame.
you would need to do custom plumbing with both motors. with the small block you would need you would need to fabricate headersthen weld up an exhaust system, the 20b already comes with the turbo manifold and down pipe, you would just need a mid pipe welded up.
with the SB you would still need a transmission and transmission mount, and custom drive shaft, or just make a custom bellhousing and use the mazda trany and custom fly wheel. with the 20B I believe you can bolt it up to the stock rx7 trany.
you would also need an ignition system for the SB.
you would also need a manifold and carb for the SB, depending on how much power you are making this could cost $500-1500 easy. or you can go with an EFI set up, kits for SBCs run 2k i think.
if you are doing the 20swap from a clip then you will have the harness and ECU, if not then you would need a haltech that will run you $1500.
I just do not see how a SB swap will be any cheaper then a 20B

ok starting off, an engine will cost you 3-4.5k, the front clip is a hell lot more and a hell lot more expensive... ignition for small block=dist.
ignition for 20b=coil packs, like you mentioned an fd tranny can bolt up to the 20b after you change counterweights and flywheel... and let me tell you that the work is tidious and I dont think I met anyone that put a 20b into an fd themsleves unless the owner owns a shop.. basically im just saying that puttin any engine in the 3rd gen is hard work even the stock one, but regardless both swaps require nice amount of money to complete....

since we are talking about v8's here how about getting a new one installed in a car that already has one? im thinking about getting my dads car and the engine has like a shitload of miles on it, the engine seems to run fine but everything around it is turning into crap and im guessing the engine is about to go another few thousand miles. it would help if anyone knows of any sites that could help me out :]

I changed the motor in my corvette in about a day, so not long. but I still think a 20B is a cheaper swap then a small block. and a 20B will make more power $ for $

Good site for v-8 swaps is www.grannysspeedshop.com

Ok that was a while ago, I have since changed my mind about v8 swaps in rx7's. 20b is the way to go no matter what...