What's easier...S52 swap into an E30 318is or into a 318ti?
 

I currently have a 1991 318is. I am thinking of upgrading to a 318ti. I might consider doing an S52 swap in the future. Which would be easier, to swap that S52 into an E30 318is or into a 318ti? My guess is that it is easier into the 318ti, especially if the S52 is going into an OBDII car.

Will they both pass most states smog inspection without a problem?

Youll need to do a few things to swap the s52 into the e30 like the oil pan, youll need one from the E34 m50. With the ti, its preactically a direct replacement to the m42/4 with a few exceptions to the variations with OBD, the chassis, and if you go with the s50 or the s52.

I would like to stick with a 96+ ti, so that would mean OBDII and an S52. Does it matter if the car is a 1997 and the engine is a 1996 (I mean for smog/inspection purposes), or does the engine ALWAYS have to be newer or same year as the car?

If im not mistaken, in ohio, its illegal to put an older engine in a newer chassis, but inspections arent strict like that nor do we have emissions. As long OBD is operatable, they can plug into it and get data, and you pass smog with good emissions, you should be fine. Im not sure how strict it is where you live, so theres no definate answers.