Can i put a 4 litre or 3 litre engine into a suzuki swift or a nissan micra or other small car?
Does anyone know?
No, you can’t.
If you’re willing to pay very clever people many tens of thousands of dollars for this kind of complicated custom work then sure. People have put jet engines in small cars like this. It CAN be done. It doesn’t even come close to being reasonable, economical, practical or even safe though.
What’s your budget?
If you’re willing to spend HUGE amounts of money you can do just about anything, but the result may not be legal to operate on public roads. You’d basically have to re-engineer the entire car. It’s not a bolt-in project.
In more realistic terms, this is not a simple task, and the easier answer is, no, you can’t do it.