NON- recomended swaps: b16 SiR/ B18A/ ZC/ d16a6/d16a8/d16a9/b20a/b21a//b18c1/b18c5/b18b1/h22a/f20/f22a/all C-series into a 2001+ civic/rsx b16 SiR/EW4/B18A/ ZC/ d16a6/d16a8/d16a9/b20a/b21a/all k-series/ all c-series/ into 92-00 Civic b16a2/ b16a3/ b16a SiR II/b20b/b20z/b21a/b20a/b18c1/b18c5/b18b1/h22a/f20/f22a/ all C-series/all K-series/ into 91 or older civic preludes/accords, stick to the F and H series. Anything can fit in any car with a hacksaw and all kinds of money... but to keep it simple, try your best to stick to the above. It will save you wiring problems and will most likely be cheaper than trying to, for example, stick a b16a SiR1 into an EG chassis vs. just buying the SiR2 in the first place. I'm sure i missed a few oddities in the list above... but basically, it all comes down to OBD. Don't know what obd is? read up on it in our articles section. The easiest swaps are more than what fits- it's what wires up properly. To wire up properly and easily, you need to stay in your obd generation. Yes, there are conversion harnesses, and it is possible, but there aren't harnesses for everything, and it is NOT recommded to make your own unless you know what you are doing for the fear sake of technicalities, and chances are if you did know what you are doing, you wouldn't be reading this thread. On top of all this, there is the issues of cable and hydrolic tranny's. The tranny needs to work with your car. Again, there are conversion kits- but same rule- its a hassle. Just buy the right one for your car, and its all set, and 99% of the time cheaper to do so. if you have a 92-95 civic: easiest swaps- b16 SiR2, 94-95 b18-b/c/c1/c5, b16a3 harder swaps- b16a2, 96-01 b18-b/c/c1/c5 difficult swaps- b16a Sir1, b18a, h22, f22 if you have a 96-98 civic: easiest swaps- 96-98 b18c/c1/c5/b hard swaps- 99-00 b16a2, 99-00 h22, f22, b16 sir1, b18a as you can see, its all about obd 1, obd2a, obd2b and obd0. find out what you got, and try to stick to it as best you can. Information on Engines, ECU's, and Transmissions can all be found on the site in the reference section.