The third trimester and what to expect.. oh what that's not right. Right, the speed swap. So you want to put a speed engine into a regular 3.
Let me get a few things straight first before I start explaining what things go into the swap.
First thing, I hope you have a big wallet. Secondly, you better have a good work ethic. Thirdly, you better have a BIG wallet.
Personally, I have seen exactly one semi-working speed swap in my life and it hardly worked. BUT... it worked. Which is a lot further along than most people get. I would say maybe 2% of people actually go through with the swap and get it working on some small scale where you can do pulls and drive somewhat comfortably.
That being said, it can be done but here's what you need to know.
Any ideas you think you might have about doing this build just empty that from your mind for just a quick second. Anything you think might fit with your build will likely not fit. Anything to do with the drive train and/or the engine bay is going to be completely different. Can you fab up some extra little mounting points? Well sure you can but that's only one issue you'll run into here.
I'm going to add dollar signs to describe how much money it will likely cost for your parts.
Let's start from the top.
I'm going to guess you have a spare DISI motor lying around complete with turbo and all supporting mods/pieces attached. I'm not going to ask how you got it but if you're like most people you probably got it from a scrap yard or a scrapped MS3 you got from someone. The first thing I will tell you is to throw this motor out if it has any more than 15000kms on it then it's likely junk. Most owners of scrapped MS3s for some reason abuse the hell out of them and it will likely have poor compression, most likely on cylinder 2. Why? I have no idea why but cylinder 2 seems to always go on these motors. The other thing you could do is have a speciality shop look at the motor and see if it's all good, assuming granny owned and low mileage but good maintenance. The main reason being the compression problem like I said but poor maintenance of these motors is unfortunately all too common. If none of these things check out, you're going to be buying a new engine. $$$$$
The next thing is did you grab the drivetrain out of the speed? If not, turn around and go get one. Your current tranny will not bolt up properly to the speed motor without serious gapping issues and also who the hell wants a 5spd in their speed swap? You're going to need the drivetrain out of the speed as well as the wheel hubs if you can snag them and they're worth it, otherwise get new hubs. Your old ones will simply not fit. The CV axles are just too different to bolt up to the current hubs on the car if I remember correctly, the splines are slightly larger on the axle from the speed than the regular 3, I'm assuming to make up for the increase in HP but I could be wrong feel free to correct me. $$$
With new hubs comes new brakes. Your current setup will sort of work but it is probably not worth the hassle of not having bigger brakes. I'm assuming you have enough expertise to do the swap so with this assumption I would think you know that with faster cars comes the need for bigger brakes. If you don't understand this then don't do this build. $$ (alternatively you can also buy the Big Brake Kit from Corksport which is a nice upgrade from stock)
If you're trying to do this as cheaply as possible then get out now. As of this point you're already out thousands. At least $3000+ for the donor car or lightly used motor, the drivetrain and/or hubs is going to be another few thousand and the little knick knacks that come with that are going to be another few hundred.
You're good so far? Awesome! You apparently either have a complete donor car(which why not just drive that one?) or a big pocket and a good set of hands. Either way you're good so far.
Let's also say you're done all of this. Awesome. Now how do I get it to fit? Here's where you're going to run into major issues. First thing, the motor with not even bolt up. The mounting points on the car, while similar, are not the exact same for obvious reasons. The reason being it's a different engine.
Let's assume you managed to fab up some mounts. Cool! Now it doesn't fit past the firewall... That's because the regular 3 was not built to have a turbo attached to the engine, nor was it intended to allow for an top mount intercooler. So now you gotta shave that firewall and hope for the best.
Make it fit yet? Yes? WOOO you're half way there(sorta). Next thing: did you think about your cooling system yet? No? I didn't think so. The first gen allowed for a small scoop built into the hood under where the grill was. The second gen had an actual scoop which was nice and I believe it bolts right up to a regular 3 without issue so that's awesome. Genwon was unfortunately not as blessed as genpu. If you want to remain stock then you NEED that hood from a speed onto your 3.
That in itself lies another issue. This particular exterior mod requires you to have a different bumper, because of the hood. Different bumper means the hood latch doesn't line up properly now and that sucks. Different bumper means new fenders from a speed(although I heard sedan fenders work fine for this? I need to do more research on that). $$
Did you forget about the cooling system? Of course you did! Now are you still going TMIC with all the issue above or going for a FMIC? FMIC no doubt, it allows for better manoeuvrability within the engine bay. With all these things in mind and assuming you're this far already you need to sort out your engine bay because hoo boy is that thing a mess right now. You need to fab up new mounts for just about every little thing in there. Washer fluid? Yup. Coolant and overflow? Yup. Wiring for your lights? YUP. $$$
Now if this hasn't deterred you at all then I would call you crazy. Or you have a deep wallet and absolutely no shame. Either way is fine.
Next thing to tackle is fabbing up the clutch and brake system after you set up your nice new big brakes and sexy 6spd transmission. This is relatively self explanatory if you know how to do these things in a car because it's pretty universal. With that said, I won't go into further detail. $$
After this you need to think about wiring. If you can't follow a wiring diagram then just stop reading here and figure out how to do that and come back. Wiring is both easy and complicated and if you don't know how to read one I suggest learning how. Wait... did you think it would just wire itself up? Hell no dude this is probably like 40% of the work right here. Everything electrical needs a new wire loom and/or some time of pin-out so you can hook it up inside. Why? Did you think it would bolt right up? No sirree bob it won't. A lot of things will carry over to the regular 3 but the ECU and all the wiring is totally different. Unless you somehow get into that spare speed car you have lying around and snag all the wiring out of that and somehow manage to wire everything up to your 3. If you plan on doing this then bless you because I couldn't imagine attempting this myself. There are WAY too many wires involved. $(free?)
Next thing is the ECU. Now this one is tricky because Mazda has this funny thing about new parts into another car. It doesn't like to share. If you grabbed that gauge cluster out of the old speed and put it into your 3 then you gotta head over to Mazda and get it reflashed to your VIN. Ask me how I know this. With the ECU you're going to need a complete reflash and retune of your new setup. Everything is going to be different on this new build and that new engine won't start itself. Like I said, this part is arguably the longest and most annoying, this includes the wiring. Without a reliable tune your car will vomit its insides all over itself. $$$$
Now you have the car started and tuned? Noice! And you somehow managed to give the ability to stop too? Double noice! oh but wait... the fuel consumption is all wrong and for some reason it runs super lean. Weird right? Wrong, you forgot about the fuel pump and fuel lines didn't you? That's right you did. but let's pretend you did it without me saying so. $$$
Assuming you have now made it somehow start and stop, and the ECU works(and the radio!), next thing on the list are other supporting speed mods.
I won't go into big detail about these but think about this: sway bars, maybe coilovers, nicer rims and tires, maybe some upgraded suspension parts or chassis parts like a half cage or something. $$$
Next comes the fun part. Interior mods! yay! I'll go into a bit of detail about these: Seats are a great upgrade from stock. The stock seats are too squishy and I find my nice speed seats sit comfortably on me and hug me a bit. The first gen speed seats bolt up just fine as far as I know however some users reported having some airbag light issues which can be resolved with a quick fix that you can easily find on google. I have no idea about second gen speed seats so I apologize about that. $$
Next thing is the dash. Do you have bose in your car already? No? Well good luck wiring that up because if it ain't stock on the car then it ain't worth it. Same goes for the temp controls. Do you have the stock knobs or did you car come stock with the electronic controls. If yes to the knobs, then don't bother trying to wire it up because it certainly is not fun.
Aaaaaaaaaaaaaaaanyways let's assume all that went well. Now for door panels. Yes they fit as far as I could tell. I have no idea about the second gen but I heard they fit too.
Another thing is the wing. Yes it fits if you have the hatch wing already on, the speed wing will fit fine, just plug up the old holes left behind. And yes the wiring matches up. If you have a hatch without the wing then no it won't fit, you'll have to drill new holes.
Am I forgetting anything? Probably. But either way, assuming all this is said and done then great! Look at that you got a working and fully stock looking speed. Anything else I missed was either in error or I deliberately left out because it bolts right up with no issue/no modification required.
Congratulations! You probably spent almost 10,000 in parts, labour and trips to the hardware store as well as a potential donor car but hey you got your speed
In my opinion though, you could have bought a low mileage slightly used working Mazdaspeed 3 for this price. Or sell your current car and get it for even cheaper.
Either way enjoy your newly built Mazdaspeed 3
If I left anything out or you have any specific questions then I'll gladly answer them. It's 3AM by now and I've likely left some things out so feel free to ask away and I'll do my best to answer them.