This write up has been written over a summer, and some things on the car have changed as I have learned a lot over the season. I am writing this in current form to skip over parts I ended up not using or swapped out.
This is the story of my 1990 Mazda Miata, swapped with a 2.0l Ford EcoBoost power plant. First off, a little backstory. This car was bought as a race car which I made a bit more streetable to run in SCCA STS autocross class. But soon, the bug for more power bit me. The obvious answer was turbo, but with the offseason approaching, I was looking to do something a little different. Now, this isn't necessarily a new swap, but there for sure aren't many Ecoboost Miata's out there as far as I know. So, after doing plenty of research from the limited forum posts out there, I elected to jump in head first.
So, why EcoBoost? First off, it's light. Ford claims ~330 lbs for a dressed engine, which is on par for what the stock Iron 1.6l weighed. Second, it comes already turbo-ed, so the already stout stock 250 horsepower could easily be turned up higher with gobs of low end torque thanks to the DI setup. Third, why not?
The main challenges from this swap come from the packaging of the engine itself. For one, it is significantly taller than the 1.6l engine, as well as being from front wheel drive cars, they take a bit of modification to convert them to a rear wheel drive orientation. Second is the high pressure fuel pump (HPFP) that hangs off the back of the head, which was going to require some firewall modifications to make happen. The HPFP is a staple of direct injected engines, and there was no way around trying to move it as it is driven off the camshaft, and is responsible for 2,000+ psi at the injector.
Let's dive into the swap! First off, removing that old 1.6l. Super simple, a buddy and I had it out (intact) in under 2 hours. (Thanks Seth :)
Next off, it was up to a local scrapyard to pick up the new (to me) EcoBoost. This engine came out of a 2013 Ford Escape. I had a few criteria for picking out a scrapyard engine. 1) I wanted all of the wiring, as I wasn't sure what my plan was for an ECU. 2) I wanted it to come with the turbo - purely for simplicity 3) I wanted it from a rear-ended car for hopefully obvious reasons. 4) Not a Focus ST engine because they have either been beat on their whole life, and scrap yards charge 75% more for the same engine.
After getting it home, we sat it in the bay to see how it would look, and quickly realized it was going to take a good bit of persuasion to get to fit.
As stated before, this engine came from a FWD car, so several things needed to be swapped around to have it in a rear wheel drive setup. The oil pan was the first big issue, as the Escape used a front sump oil pan. This was a pretty big issue as the sump sat right where the front subframe’s crossmember was located, thus, we needed a rear mount pan. But nobody makes a rear sump oil pan for an EcoBoost, except…Ford! A 2004 ranger uses a Duratec based engine, and since an EcoBoost is basically a boosted Duratec, it would bolt right up. Ford also uses a balance shaft in the oil pan to somewhat offset the naturally unbalanced 4cyl, so this needed to be deleted. All that really entails is unbolting it and installing a plug into its oil feed. This also frees up about 10lbs! A modified Ranger pickup tube and gasket were installed, and the oil pan situation was buttoned up.
Beyond this, we needed to get the coolant coming off the front of the engine. Thankfully, the 2.0’s bigger brother, the 2.3 is found in the 4cyl Mustangs. So, a quick visit to E-bay and I ordered up a Mustang water pipe and coolant outlet which bolts right up to the back of the 2.0 and brings the coolant outlet to the front of the engine. Continuing on the EcoBoost mustang trend, a mustang intake was used to bring the inlet to the front of the engine in order to make the charge pipe situation…possible.
Next up was the barbaric task of getting this thing to fit. We first turned our attention to the subframe. The EcoBoost is a bit wider than the stock engine, so we needed to cut out the sides of the subframe to be able to lower it in. Second, we needed to get the engine lower down into the chassis. I strongly did not want to cut the hood on this car, so getting the subframe as low as possible was high on our priority list. And yes, I know a V8R subframe would have worked better, but that was a bit pricey for me. In this instance. So, we cut the crossmember of the subframe shorter to accommodate the taller engine. This was all later braced back with a ¼ inch steel plate and welded back up. I am, by no stretch of an imagination, a welder. So, much of the fab on this project was done by me, tacked up, and brought to a local welder to have done properly. I don't have many photos of the firewall cutting process, but we basically took out the faux firewall between the bay and the wiper cowl, then cut along the seam of the firewall and the wiper cowl tray, hammer the firewall back for clearance, and welded the seam back up.
For engine mounts, Ford conveniently puts some threaded holes on the side of their blocks (not sure why) but we elected to use those as the base of our engine mounts. So, with more steel plate, we made plates to mate up to the block, with tabs on them to accept a polyurethane bushing. On the subframe, square steel tubing was welded in place on the subframe end and onto the bushing on the other.
Next I turned my attention to the intercooler. The EcoBoost uses a sensor (throttle inlet pressure sensor - TIPS) in the intercooler in addition to the traditional MAP sensor in the intake manifold. This sensor is traditionally mounted in the cold side of the intercooler on a Focus ST, so I elected to use an aftermarket Focus ST intercooler I bought off Facebook. It ended up working out great, and I mounted it to a couple of radiator threads the Miata had. Going off of this cross bar, I added some brackets to capture the lower part of the radiator, as well as some brackets over the core support to locate the radiator into position. I was able to track down an upper radiator hose that was able to make the transition to the left side of the bay for the radiator. The radiator of choice was a Speedway motors tripp;le pass for what is intended for a Mustang. Hindsight, this was a bit overkill, but the car has never been above 195 degrees (90.5c) even in 100 degree weather beating the snot out of it. It would be even better with hood vents.
Turning attention to the charge pipes, I elected to make them out of steel, mainly for the simplicity of fabrication. These were another item I tacked up and took to a local welder to make sure they would hold pressure.
Moving into the drivetrain, I picked up a type 1 Torsen diff off Facebook, and got it installed into my subframe with some polyurethane bushings. This was super simple as it was OEM parts going where they were intended.
For the transmission, this is where some of the special sauce comes in. I looked at several options for the trans, and I was looking for simplicity to go with the Ford MT-82, but it was heavy as well as expensive. There is also the NC 6 speed, but they are a bit fragile and hard to find cheap. So, I turned to the folks at JEM-Sport, who are the EcoBoost swap GODS. These dudes are awesome. So, with them supporting the BMW ZF transmission for their swaps, and with the drift community supporting them as much as they did, it seemed a great option (it is) They are good for ~600 horsepower, and one of my favorite features is how they use a chassis mounted shifter, which allows me to mount the shifter where I want and extend the shift selector bar to fit. The clutch is a ClutchMasters unit from JEM-Sport and tested by god Jesus Chelsea DeNofa in his EcoBoost swap, so I have no qualms about it being able to hold up. For the clutch master cylinder, I upgraded to a ¾ inch master cylinder from a 1980’s toyota land cruiser - it's surprisingly easy and there's a write up on the Miata forums on how to do it. It did need a custom crossmember made, which was pretty simple and I simply located it to the frame rails. Another benefit of this was easy pinion angle adjustment, as I cut the PPF down in order to have it land to the crossmember, and bolted it in place. This allowed me to use thick washers to space the PPF up and down to dial in my pinion angle. The shifter was taken care of by Garagistic, and their product is top tier.
Let's talk about plumbing. First off, the oil filter. The EcoBoost’s oil filter housing stuck off the rear passenger side of the engine block, so I needed to do something to get it away from the subframe. Mountune sells an oil take off plate which gives me a simple threaded hole to run a -10an line to a remote oil filter I mounted up on the driver’s side of the engine. ]
For fuel, the ecoboost uses a returnless setup, so I elected to run a fuel pressure regulator in the rear of the car to avoid having to run another return from the front of the car back. Speedway sells an LS fuel pressure regulator that's set already at ~68 psi with -6an fittings already braised on, so it was pretty easy. In the tank I upgraded to a DW200 fuel pump from Deatschwerks, and ran some nifty hardline to -6an adapters for the fuel lines. Since the ecoboost uses a high pressure fuel pump, the ECU needs to know the low side fuel pressure as well, so I went back to good ol ebay to buy a Focus ST HPFP feed line, popped one of my hard line adapters on it, and it was ready to rip.
For the exhaust, the challenge came that the ecoboost’s exhaust comes off the passenger side while the Miata has it on the driver’s side. Since I still have a PPF, I would have to route the exhaust under the transmission. Not the end of the world, but its a liiiiiiitle close to the ground. This will be addressed at some point, just not now. I elected to use the second half of the Miata’s exhaust that it came with when I bought it - it's some kind of ISR exhaust, so I just built the exhaust from the turbo up to it. Eventually I'll get fancy and do 3 inch stainless all the way back, but for now mild steel is what we're rocking with. The downpipe has v-banded so I can pop it out easily.
Next up I needed to feed the turbo, and anyone who knows little 4 cylinders knows that their charge air temps get spicy, so anything I can do to keep the air feeding the turbo close to ambient is crucial. So, to do this, I elected to use one of the Miata’s headlights as an airbox, and use mini lightbars for the headlights. This allowed me to build a box around the filter to keep it as cool as possible. Ford uses a temp sensor right behind the filter, so, you guessed it, Ebay! Picked up an ecoboost filter elbow with the sensor in it and we were good to go. I made the filter enclosure out of some super thin aluminum and wrapped it and the intake pipe in gold heat reflective tape. It actually works pretty well! Charge air temp at the manifold is usually around 10-15 degrees above ambient.
Lastly, wiring. Since Ford no longer makes an aftermarket ecu/harness solution for these cars, it was back to JEM Sport for their solution. Their wiring solution allows the car to run standalone by simply connecting power, ground, and ignition. For me, peace of mind with an engine harness on an engine with this many sensors and wires was worth a bit of premium. Their support is top notch and comes with all of their products. I mounted the ECU on the left side of the engine bay right next to my fuse block. Motor started the FIRST TRY. The harness has 2 CAN leads coming off it that I ran into an AIM dash, and this is a killer combo as it does not lag at all. The stock Miata wiring remains, but all it does at this point is handle the lights, and I just have a switch panel with ignition, start, fuel pump, and radiator fan. Took a quick first drive, and everything worked as intended! After getting the car home and checking it over again, we headed to the gas station for our first fill up! Later in the season, he car was tuned by Ryan at Engineered Motorsport Solutions over HP Tuners for some extra spice.
Finally, the fun bits. This car is built to the XB ruleset from the SCCA, and it has some generous allowances for areo. The front splitter was made by yours truly with some ½ inch birch plywood with some bed liner on it, and the wing is from Nine Lives Racing. These two are a great combo and make the car significantly more planted even at autocross speed.
That more or less wraps up this build. I am writing this at the end of the season, and after some time with the car, this is a very stout setup. It's currently sitting 5th in my local club’s PAX championship, including some shaky first events learning the car and setup. Ill make another post soon with all of the mid season changes and updates. I hope this convinced you to shoehorn an EcoBoost into your Miata, and if you have any question send me a dm on @miata.st on instagram. Thanks!
