Engine Swaps

I can read your mind. Your darkest secrets and deepest desires. Your fears and phobias. That incident in your junior year of high school? Just hope that I never decide to blackmail you. I know all. How? Don't concern yourself with that. Within your id, ego, and superego, I have determined this: You want a fast car.

Easy enough. How are you going to do it? Buy an NSX? Well, maybe, if your name is RJ. But it's not, so you will have to keep the car you already have. I know your car is a normally aspirated slug. It can't get out of its own way. It gets humiliated by factory turbocharged Chrysler minivans (had that happen to myself, actually). What are your options?

A nitrous oxide setup is one choice. It's inexpensive and effective but requires a vigilant watch to keep the bottle full and the engine from leaning out. A turbo or supercharger are the other choices. But again, care has to be taken in making sure the engine stays healthy. You want power that you don't have to worry about. This brings us to today's classroom discussion: an engine swap.

The basic concept of an engine swap is installing a large engine into a small car in the hopes of having a vehicle with a very high power-to-weight ratio. Usually this means creating a vehicle configuration that is not factory original. Much of hot-rodding's history comes from engine swapping. After World War II, kids started dropping flathead Fords and Y-blocks into their Model Ts and As. In the musclecar era, special dealerships like Grand Spaulding Dodge and Don Yenko Chevrolet put engines in cars that they were never meant by their respective manufacturers to have. The most famous type of engine-swap car is Carroll Shelby's Cobra, consisting of a lightweight AC body and a 289ci or 427ci Ford V-8. Today, Honda is the most popular make for engine swapping.

The most positive aspect of an engine swap is the gain in horsepower without a loss in reliability. If a stock Honda Civic (1.6L engine with 106 hp) receives a stock Acura Integra GS-R engine (1.8L engine with 170 hp), the Civic gains an instant 64 hp. And since the GS-R engine is completely stock, it should run for years without your worrying about its general health.

Installing a larger engine into a car also creates a better base from which to build power. Using our example again, the stock 1.6L Civic could be made to generate more than 170 hp with a turbo or nitrous system. But as more nitrous or turbo boost is used, the engine will reach the limits of reliability and power. With its extra displacement and generally stronger construction, the GS-R engine can handle more boost or nitrous than the Civic engine. The GS-R allows engine output to be taken to the next level.

An engine swap brings with it a couple extra bonus points as well. Even people with little or no interest in cars know that a Ferrari 355 is not to be messed with. It just looks fast. But a mid-'80s Toyota Corolla? No respect, man. Consequently, the Corolla's lack of respect and its economy car (lightweight) status can be used to create an ideal engine swap vehicle. Nobody expects this car to have a 190hp engine under the hood. An older car is also ideal in that it is generally lighter than its modern-day counterpart. More-rigid frames, additional safety features, and more standard luxury items are to blame. The current VW Golf carries 40 percent more of an original Rabbit's curb weight, for example. An older car is also likely to have an aged powertrain. Rather than having the original factory engine rebuilt, why not just buy a larger engine and install that?

First, let it be said that you can swap in anything if you really want to. A Monster Miata (Ford 5.0L V-8-powered Mazda Miata), a Shogun (a Ford Fiesta with rear-mounted Ford Taurus SHO V-6 driving the rear wheels), and a Legend-powered Civic are proof of this. About 15 years ago Car And Driver magazine featured a Honda CRX with two 1.8L Accord engines. One Accord engine was in the stock position; the other was in the rear cargo area driving the rear wheels. It was built by Racing Beat of Anaheim, California. The point here is that any engine or car can be used. But the more extreme the swap, the more money and expertise will be required. For most people, the constraints of income and a good shop severely limit the possibilities. So what is possible?

Certain cars just make better engine-swap candidates than others. A '97 Prelude comes with a 195hp VTEC engine. What possible engine could be installed without much hassle that would provide a serious increase of horsepower? Uh, an NSX V-6? Yeah, get real. No, not much potential engine swapping with a new Prelude. The cost-efficient thing to do is gain power through bolt-on parts.

The same case could be made for a factory turbo Eclipse. Only one Mitsubishi engine is more powerful than the 2.0L engine--the 3000GT VR-4's 3.0L V-6. But that engine is already a really tight fit in the larger 3000GT. For the Eclipse and 3000GT (and a lot of other factory turbo cars), money is better spent by upgrading the existing engines and turbos. These cars also serve as a good example for cars that have trim lines with wide-ranging degrees of performance. The base 3000GT comes with front-wheel drive and a 12-valve 161hp non-turbo V-6.

Would it be possible to swap in the VR-4's all-wheel-drive and turbo drivetrain? Certainly. But would it be cost-effective? Probably not. For the price of pulling out the base 3000GT's engine, acquiring a complete VR-4 drivetrain, and installing it, you could buy a factory VR-4 for less total money.

A first-generation CRX is a different matter. It's lightweight, relatively old, and can accept more powerful engines from the Honda/Acura lineup without much problem. A same-generation ('86-'89) Acura Integra engine will fit, as will the Japan-only 130hp engine found in Civics and CRX Sis. How do we know this? Well, people have gone out and done it. It has been tested and then duplicated by other first-gen-CRX owners. Honda owners are fortunate, because there are so many people out there trying engine swaps. Most likely someone has done a swap before you and has learned what fits and what doesn't. But what if you own an '86 Mazda 323? Will the '93-'96 MX-6's 164hp V-6 fit in your car? To be honest, we're not sure. It's quite possible, but we've never heard of anyone doing it and therefore have no basis to go either way. In this case, the ball lands in your court. You can try to find someone else who has done the V-6 swap, but most likely you will be on your own.

OK, let's say that you have a car that you are willing to perform some engine-swap magic on. Images of a reliable 1:10 power-to-weight ratio dance in your head. Where do you start? First off, you need an engine to install. If you are having a shop do your engine swap, then the shop most likely already has a line on obtaining surplus engines. Good shops sometimes have access to an engine importer, allowing the option of installing a Japanese-spec engine. Japanese-spec engines often produce more horsepower than their American counterparts. If you are locating the engine yourself, salvage yards and engine rebuilders will be your best sources. If you live in a part of the country where the import scene hasn't quite caught on yet, finding a rare engine might be difficult. In this case, contacting a mail-order engine rebuilder is the way to go.

While it's distasteful to think of, there are stolen engines out there. If the price on an engine is too good to be true, it probably is. If this is something you are considering, be prepared to live with the risks and your guilty conscience (remember, I can read your mind). Before you purchase any engine, take the time to make sure it is in good condition. You will need pretty much everything including the block, head, accessories, transmission, wiring harness, and (most likely) matching computer.

Keeping your engine swap legal is very important. Examine your state's vehicle code or contact the DMV to see what's legal and what's not. In California, the law says that an engine must be of the same year or newer as the car and be California emissions-legal. To avoid any hassles, it should also be of the same engine type that was originally available from the factory in that particular body style. Hmm, that's kind of a problem. Besides sidestepping the law (and we would never do anything like that), there are a couple options. The best is to have your entire car certified by the state by going to your local referee station for examination, testing, and BAR Vehicle Identification Label approval. You can call 800/622-7733 for an appointment. The other option (and definitely more work) is to keep the original engine on hand and swap it back in when you have to make a trip for the smog test, but we don't recommend doing it (legal reasons and all).

Determining the dimensional needs of the bigger engine is the next step. Hopefully, you already know how hard it will be to install your new engine. Some engines will bolt directly in utilizing the factory engine mounts. Other more extreme engine swaps will require moving and welding new engine mounts, fabricating new engine mounts, and possibly cutting or modifying the frame. Even if an engine physically fits, it is not the end of location problems. Proper mounting is very important. Make sure that the engine is level, tight, and in the right position. If the engine is not tight or located in the right position (the right position being determined through trial-and-error of engine-swappers before you), normal engine movement can cause it to rub or even damage various accessories within the engine bay. Improperly installed Honda Prelude engines in Civics are well-known for banging their intake manifolds on the firewall when the engine torques. Engine position is also important for the transmission and axles. On front-drive vehicles, increased wear and diminished performance will occur if the axles are not aligned as straight as possible.

Getting the wiring and computer right on an engine swap is probably the hardest part of the job. The engine management computer that matches the engine being swapped in should be used if at all possible. If not, the computer that's in your car might not be able to operate the new engine properly. This can range from limited performance (going into "limp-mode," for example) to not being able to operate it all. The key is to interface the new engine's wiring harness and computer to the car's original harness.

Problems arise when the new engine has extra plugs or sensors that the car's original wiring harness doesn't have. If you install a VTEC engine into a car that didn't come with a VTEC engine (and hence no VTEC wiring), it makes things much more difficult. The same can be said for trying to install an older engine into a OBDII-equipped vehicle--the older engine doesn't have the connections to allow OBDII to work. To make sure the wiring process goes as smoothly as possible, two factory manuals are required. One for the car and one for the car the new engine came from. This way, you can trace wiring diagrams and match the wiring harnesses and computer.

Another problem for engine swaps is making sure the new engine stays cool. Most likely, the new engine is bigger and generates more heat. The radiator that matches the new engine or at least one that has similar cooling capabilities should be used. You can also modify the capabilities of the stock radiator with extra fans. Make sure the diameter of the coolant hoses is sufficient to allow enough coolant to flow. Other things to consider are the shift linkage, axle splines, and suspension. On some cars, the new engine's shift linkage will be the correct length and will bolt right up. Other cars will require modification to the shifter linkage. It just depends on what kind of car and engine you will be using. It's the same thing with the half-shafts of the new transmission. Whether they are the right length and spline for your car's wheel hubs will vary. If not, you will need to spend time matching them up, possibly requiring axles from a completely different vehicle. Since the new engine will almost certainly be heavier than the engine you are taking out, make sure that your car's suspension is up to the task with stiffer springs and shocks. That is also an important point for car owners who value handling to a high degree. A heavier engine will degrade handling abilities, especially on a front-drive car. You can counteract this to some degree by removing weight from the engine bay (take out the air-con or power steering) or moving weight to the rear (move the battery to the back).

An engine swap is a great way to get more reliable horsepower out of your car. The larger engine will also allow more power than would otherwise be possible with the stock engine. Most engine swaps are not for people on a McBudget. If you own a base model of a particular vehicle and are thinking about swapping in an optional factory hi-performance engine (swapping in a Nissan Sentra SE-R engine into a base Sentra), analyze how much it will cost to buy and install the higher-horsepower engine versus just buying another car with the bigger engine already installed. Generally, it will be cheaper just to sell the base car and buy the upgraded car, though insurance rates will rise with the upgraded car.

On an older car with an easy engine swap, expect a price of $1,500 for the engine and labor. High-performance engines cost considerably more to purchase. An Integra GS-R runs about $3,000 and a twin-turbo Supra engine is around $7,500. Labor on extreme swaps can run from $1,000 to $2,000. Also make sure that your swap is legal. If you get busted, you risk vehicle impoundment and loss of your engine. The best way to approach an engine swap is to learn as much about the process before you start. Find people who have done it before and ask lots of questions. Some shops will give you information; just be nice and courteous. Little car, big engine--it's the only way to fly!