If you are into bigger custom modifications, Chevrolet sells an eCrate engine kit. It's basically the drivetrain and battery pack from the Chevy Bolt. You have to figure out how to package it in your car of choice. As a demonstration, they used it to convert a 1977 Chevy Blazer.
Edit: Note that removing the IC engine means you also lose heat, air conditioning, power brakes, and power steering. Those systems all rely on waste heat, belts, or vacuum lines from the IC engine. You need to replace them all with electric devices.
Note that removing the IC engine means you also lose heat, air conditioning, power brakes, and power steering. T
I know people are used to it, but AC and power-steering are arguably luxuries you can do without. Especially if the car's light.
The problem is people are also unwilling to uncompromise on range and want an arguably overpowered motor and acceleration, which necesitates a large battery. Large/heavy battery -> power steering + different suspension + better/more expensive brakes + different wheels + ... + ....
Chuck in a 30hp engine into a classic beetle, limit the range to 100km, and you need a far smaller (and less heavy) battery and it'll likely be a far easier conversion that'll likely still outperform an actual classic beetle.
If you want to turn a classic beetle into a tesla killer, with modern luxuries, it's going to be heavy, difficult to make and expensive.
That heavy torque is one reason to keep the car's gearbox rather than go with direct drive. Chevy's eCrate kit specifies that it's intended for use with an automatic transmission, not direct drive.
DIY EV kits are a thing, but a quick google shows some wildly varying prices. Probably depends on exactly what kind of car you are trying to refit and the performance you’re looking for.
There's a company in my town that electrifies vintage European cars. I'm told that the bulk of the work is figuring out where to put the batteries and how to cool them.
Absolutely min things to swap
Gonna need a battery of some kind
3 phase induction motor (probably)
Motor speed controller
Some sort of battery charger
Big inverter for big motor
An ecu-like thing to control everything
Specifics about how to make this all work in a vehicle will depend wildly on which vehicle. Some basically can have these things bolted on, others require special assemblies to get the power to the wheels somehow.
An ev swap can be (relatively) cheap and simple or wildly expensive and difficult just depends on your goals.
Most of the parts I mentioned are available as off the shelf components and sometimes even as a swap kit.
Friend of mine's dad, back in the 90's, ran a small shop converting VW bugs to electrics w about a 40 mile range using just a bunch of car batteries. The shop went under after a little bit, not enough interest. But, it's very possible.
VW Bugs were so easy to modify. I had a friend in highschool that put a pinto engine in one. It had open headers and the gas tank was a 2 litre Sprite bottle strapped to the frame. We took it off-road with no seats. It was loud as hell and painfull when jumping hills.
There were ads for conversion kits in the back of Mother Earth News way back in the 80s. They didn't work terribly well, but a certain class of bearded person were all about it. (It's me. I'm the bearded person.)
When I’ve mulled over this question, placement of the batteries is usually the sticking point. Electric cars are designed to put the heavy batteries in a relatively advantageous spot for handling.
What's a common package for battery units? A full Leaf dropout is an awkward shape and 4 buckets of 18650s are a headache. Is there something common in between? I've got nothing but empty space between my frame rails and figured that'd be a good place to add some batteries without having to go crazy in the ex-gas tank spot
Not sure there is a truly common package. Each manufacturer seems to be doing their own thing (unless they’re a small fry directly buying parts from some other manufacturer already doing their own thing). So I guess a common package might be “whatever’s in a Tesla”, but that’s not a very satisfying answer. And those are often just arrays of 18650s internally.