In the next year or three I'm planning to install a new engine in my 84 4 speed Fiero. Eventually I will build it into a sick daily driver I can take to the track and corner like a madman. The duke has a million little things it needs, but drives decent. Doesn't quite make the power I want. There's an issue with a clutch rattle when I first start moving, I'm hoping it's the original transmission and engine mounts. I can't get my car above 85 without hitting the 5k redline which makes it more of an "in town car," super lame. Differential maybe? I don't even know where to start with that one. I'm wanting something fun, but economical. Easier would be nice, but is not necessary. I would like a light engine, to help the car's balance and center of gravity. I was thinking maybe a vq35, any information on that swap would be cool. Something around 200 hp would be my minimum, but 400 or more would be super cool. It would be nice if we could keep the orginal milage, but as long as it's decent on gas. Better than the original 50 highway would be awesome, but i'm happy as long as it's better than my 06 taurus's 30mpg, wonderful car. Durability and ease of maintenance is preferable. I would like to keep the original 4 speed, it can take some power from what I hear, but would honestly feel better with a newer transmission in slightly better shape. I've never done an engine swap before, but I've done a decent amount of work and feel I could probably do it. Just keep working on it, and eventually it's done, right? I have access to a welder and plenty of tools. I'm looking for ideas, and conversation.
Your goals are not very realistic. Unless you have deep, deep pockets, sell this car and buy one that is already modded and closer to what you are looking for.
3.4 and 3.8 V6's are popular swaps but you are barely hitting 200hp unless you get a Supercharged 3800. AND a swap like this is a bit more difficult in the 84 than it is in the later year cars.
