Car is Toyota Vitz, 2005, ~ 115,000 km.
It has a three cylinder engine and I'm considering changing it to a 4 cylinder engine.
Apart from the engine itself, what other things would I need to change?
What’s the reason for the swap?
The transmission, ALL the electronics, ECU, PCM, BCM, fuel system, throttle linkage, engine mounts......etc. etc.
To go from 3 to 4 cylinders it definitely isn't worth the expense it would take.
Oh, there would probably be a LOT of stuff to change - do both use the same transmission? The engine control computer definitely, probably some of the on-engine accessories, like the alternator, AC compressor, power steering pump etc. You might have to move things like the battery and coolant overflow tank.The radiator for a larger engine would be larger. It would probably take a lot of research, a lot of parts, and a lot of advanced mechanic skills.
I'd be willing to bet you that if you take this on, you'll wish you just sold this one and bought a used 05 4-cylinder Vitz instead.
If you can & must have 1 more cylinder, look for the 1.5L 4cyl engine which was sold in the Yaris hatchback in other parts of the world.
Other members have already mentioned why it might be a bad idea & the end of a trouble free ownership experience.
C'mon... Its a 15 year old Toyota Yaris basically. They are cheap cars, and you got 15 years out of it. Don't sink money just to end up with one more cylinder. Get yourself a Corolla if you are nuts about having an I4
