I frequently get calls asking “What should I do with my car?!” and asking what engines a customer can swap in. Engine swaps are a good thing to think about, but there are a wide range of items to consider before you decide on doing a swap. Doing an engine swap can be a simple bolt in to the factory mounts or as sophisticated as having to notch the frame rails, fabricate all of your own mounts, custom axles, and major wiring. There are several things to consider. Will the new engine get you the power you want? Will the engine fit? Will it work with the transmission in your car? Will the swap require different wiring? Has anyone done the swap before? Do you need to pass emissions, and if so will your swap pass emissions?
The first thing to take a look at is whether or not someone has done this swap before. This can help you get the job done quicker and help you avoid hidden problems that someone else has already encountered. The internet makes checking to see if someone has done the job before much easier than in the past. Forums are also another big help, and a great place to look. Not everyone publishes an engine swap but if you can find someone on a forum who has done the job they might indulge you and offer up a few pointers. Let’s look at the big picture: If the engine you are installing requires everything to change, like the engine, transmission, wiring, axle, shifter, etc. there is probably going to be a lot of time and money involved with the swap.
Engine fitment is what you should look at next. If the engine you’re planning to swap won’t work with your transmission, make sure you get the all dimensions of the engine and transmission together. One dimension to remember is the height which often gets overlooked. The engine will move in the engine bay and the last thing you want to do is get the engine installed and then discover your engine hits the hood under acceleration.
If the engine you are mounting is not a bolt in make sure you take a look at how the new engine mounts. Find engine bay pictures online or a car to look at with the engine factory installed. Most manufacturers like Mazda keep similar mounting points. There are exceptions to engine mounting so you need to make sure you address this. If you are installing a different transmission with your engine, look at the mounting for it as well.
Transmission mounting is critical. You need to have the transmission located perfectly to get the axles to line up. Check and see how the new transmission is shifted. Does it use a cable shifter or a rod shifter mechanism? How does the clutch operate if it is a manual transmission, hydraulic or cable type? Are the axles larger in diameter and do they have a different spline count? You might have to consider getting custom axles done if you are not able to find a bolt in part.
Cooling is also an important item when considering a swap. Do the radiator hoses come close to lining up with your radiator? Does the radiator you have carry enough capacity to cool the new engine? Forced induction engines will generally require larger radiators. If the new engine is turbocharged, make sure you remember that you will need an intercooler and a place to run piping for it.
Wiring is the part that scares most people out of doing an engine swap. Most swaps are using engines from newer cars and thus include some extra systems that your car may not have in it. Make sure you have the wiring books for both the cars you are swapping the engine from and to. Engine wiring normally is the most difficult. If you can get the engine wiring that belong to the new engine it will make the job easier. Sensor changes, plug differences, and wiring routing all are important items to look at. A nice side advantage to keeping the newer wire systems is emissions. This can also be a drawback with OBDII systems and the level of complication they can present. Most states will allow you to swap to a newer engine if you keep the emissions controls intact. Make sure you check with your local EPA for emissions info before you do the swap.
Exhaust is the last thing I will cover. It is normally straight forward to get the exhaust connected up to the existing system on your car, if it is adequate for the new motor. If it is not, look at building or getting a new one built. Make sure to add a catalyst if you are going to be driving your car on the street and required to pass emissions.
To review the swap check list:
So have I scared you off? The items I have brought up above are all things I have learned from experience doing engine swaps. My goal is to make sure you have everything covered before you start a swap. I have had quite a few calls of people wanting to swap a DISI MZR engine into Proteges, MX-6s, and other cars. I think this will be the next big swap we see once someone takes on the challenge.