How do people fit engines into cars not ment for them?


I’ve seen engine swaps and stuff and I am wondering how people fit engines/transmissions that are for bigger cars.

I’ve seen the SRT Hellcat in the Prius and how they modified the car basically around the engine but I’m interested in like how they fit something like the Viper V10 or LS into cars that don’t have the same engine compartment but it doesn’t look like they did anything to it.

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A lot of times non-essential systems like air conditioning will be removed, and other accessory things can be moved around relatively easily.

Also older cars used to have a lot more space in the engine compartment.

Sometimes a body lift and similar modifications help increase space where needed.

When you see a REALLY wild engine swap where the car does not look heavily modified on the outside, what they USUALLY do is remove the fenders, hood, grill, bumper, etc. All the parts that you see from the outside (also called the front clip). Then they’ll cut away the structure of the car from the firewall forward. Then they build up a new structure to carry the desired engine and transmission. Once that is done, then they can build up mount points to carry the original front clip.

If you’d like to see this done in detail, I highly recommend the “Project Binky” series from Bad Obsession Motorsports on YouTube.

The short answer is : with great difficulty. A buddy of mine has been working on his LS swap for 2 years.

V8 engines are actually pretty small. Most V8s used for swaps use pushrods rather than overhead cams. That means there is a single cam shaft in the middle of the engine, and rods go up each side of the V to open the values.

Pretty much every other engine used these days is dual overhead cams. That means the cam shafts are on top of the cylinders which makes the engine a lot taller and wider.

Here is an example of the size of an OHC engine vs pushrod:

So a pushrod V8 can be about the same size as an OHC I4 or V6, making not that much difference in space needed.

Obviously a tiny 1.5L I4 will be a lot smaller, so in that case a lot of modifications will be required.

It comes down to a question of physical space and modification, if needed.

If the engine you wanted to put into another car was smaller than the engine bay (i.e. if there’s still free space), then you would simply create engine mounts that hold the new engine in place using the mounting holes in the engine bay that were intended for the original engine.

Historically, you would’ve had to make these yourself. With today’s car scene and how many engine swaps take place, there’s a chance you find someone who manufactures engine mounts for a given engine to go into a given car/engine – this is particularly true for popular engines, like Toyota’s 1JZ/2JZ, Nissan’s RB25/RB26, BMW’s S54/S65, etc. Keep in mind that engine mounts will be unique to a given engine + engine bay combination, rather than for just that engine.

As for engines that are bigger than the engine bay of the car that you want to put them in to, let’s use your Toyota Prius/SRT Hellcat example. The Toyota Prius is an economic car and doesn’t have a very big or powerful engine, so its engine bay is quite small (because why would you create more space than you need?). The SRT Hellcat’s engine is a very big engine in itself, so it’s not going to fit.

So what do you do? You create more space. There are two main ways that people do this.

The first is to modify the engine bay/the car itself by cutting out parts of the engine bay where the engine doesn’t fit – this could be anything from cutting out small corners to cutting out major parts of the car itself.

The other is to take parts off of the engine to make it smaller. Engines will have parts and accessories on them that are for the driver’s benefit but are not strictly essential for the engine to work. For example, an engine from a modern car could have a power steering pump and an air conditioning compressor bolted onto the engine.

These parts could be sticking out and preventing the engine from fitting, but removing them could then allow the engine to fit. If you remove a power steering pump, you then lose power steering – it’ll be physically harder to turn the steering wheel, but you can still drive. If you remove the air conditioning compressor, you won’t have air conditioning anymore, but you can still drive a car without it.