The common image of the engine swap is one of performance-obsessed enthusiasts trying to squeeze as much acceleration out of their vehicles as possible. In actual fact, there are a myriad of reasons why people remove their stock engines and replace them with something different—and more power is only one of them.
What are some of the driving forces behind engine swaps? Let's break down the most common cases where it's out with the old, and in with the new under the hood.
Original Engines Too Hard To Find
Anyone who's ever owned a particularly uncommon classic car will know the pain of trying to locate rare parts—or the nightmare of attempting to locate a low-production engine. If your vehicle was sold in piddling numbers, has little or no dealer support at this point in its existence, or hails from a long-extinct brand, chances are you're going to have a hard time finding the right factory engine to install when your original goes kaput.
It's natural, then, to look elsewhere for a new prime motivator. Some individuals keep it in the family by sourcing a similar power plant from the automaker, while others look elsewhere for inspiration. Keep in mind that borrowing from another brand is something that even car companies have done and continue to do with particularly smaller operations such as Jeep, Studebaker and AMC when they couldn't afford to develop brand new drivetrains for each and every model.
Cost Of Rebuild Is Greater Than Cost Of Swap
Say you've got a motor in need of a rebuild. It's an older design, but you take it in for a quote anyway. When you take a look at the number at the bottom of the shop estimate, you swallow hard, and realize that for the same amount of money, you could install a more modern, powerful and efficient engine.
Sound farfetched? It happened to me, and was one of the reasons why I decided to swap in a newer motor rather than rebuild a still-running, but not nearly as capable stock unit. I'm far from alone on this, either, as engines like the small block Chevrolet or LS V8 have been used to revive vehicles ranging from 12-cylinder Jaguars to Porsche Boxsters suffering from catastrophic failures to their complex, and costly-to-rebuild power plants.
Reliability Issues
The best way to keep a favorite car alive and healthy is to drive it as often as possible, as that's often the path towards ensuring regular maintenance is performed and any persistent issues are dealt with.
Unfortunately, some vehicles simply aren't reliable enough to use on a daily basis in stock form, even when everything is in tip-top shape. Some fantastic vehicles featured engine designs that simply couldn't cut it in the real world, and for those who want to keep piloting their preferred vehicle and enjoy everything else it has to offer, an engine swap to a more reliable motor is often the only option. The previously-mentioned V12-powered Jaguars are a good example, with entire businesses built up around swapping in low-cost alternative engines for owners too frustrated to keep pouring money into their original drivetrains.
Off-Roading and Towing
Want a diesel SUV, but don't want to pay a ton of money for a full-on luxury import, or park a behemoth like a full-ton Suburban in your driveway? Your options are limited—unless you're willing to swap.
Stuffing diesel power under the hood of trucks in order to improve their towing and efficiency under load is a time-honored practice, especially since it took so many years for the Big Three to start offering attractive diesel options in light-duty packages. Diesel swaps are also popular in the off-road crowd for anyone seeking good torque down low combined with the range-extending frugality of an oil-burning setup.
Too Expensive To Make More Power
Finally, we get to the power question—but let's look at it from a different angle. Sometimes, it's not that the stock engine can't be improved on, it's just that it would cost so much money to do so that swapping in a different motor that's more mod-friendly with a healthy aftermarket support makes a lot of sense. This is especially true of complex engine designs that are already living very close to their theoretical maximum output, or high-compression motors that aren't friendly to forced-induction turbo or supercharger solutions.
Surprisingly, some of the most common instances of this philosophy is found in the Mustang community, where owners yank out their modular 4.6-liter V8s in favor of pushrod LS engines that offer significantly more bang for the buck.
You Have One Just Lying Around
Ah yes, the lazy person's swap. If you already have an engine sitting in the garage, and it comes time to replace the motor in one of your vehicles, why not just go for it?
"Because it was there" has been the driving force for any number of unusual engine swaps, be they V8s under the hood of compact BMW sedans, Subaru flat fours in the back of a Volkswagen bus, or 1UZ Lexus motors filling up the space between a Miata's fenders. Weird combinations are often born from opportunity and creativity, rather than an actual set plan, and I'll always be thankful for the individuals willing to live outside the automotive margins and make them happen.
Is it time to make your engine swap plans a reality? Check out the basics behind installing a new engine in your ride.