When an engine fails an owner can scrap it, replace it with the same motor, or do an upgrade. That last option typically comes with some big hurdles, though for NC Mazda Miata owners, one upgrade is actually far easier than you might think.
A good engine swap usually includes at least one of the following: more performance, ease of installation, reasonable pricing, or added long-term flexibility. The one that we’re talking about today includes all of those. In fact, it might not just be reasonable pricing but outstanding pricing, and it’s a bit of a performance steal.
The NC generation of the Miata came out in 2005 (as a 2006 model) and lived until 2015. Prior to that same time, Mazda and Ford had worked very closely to co-develop several engines, one of them being the 2.5-liter MZR, which you can find as a “Duratec” in the Ford Fusion, Escape (or its sibling, the Mercury Milan), or Transit Connect. (The Mazda MZR variant was used in the Mazda3 and Mazda6). That engine, many have found, is the perfect upgrade should an NC Miata go kablewy.
The Miata came with a 2.0-liter four-cylinder in the “MZR” family that made 170 horsepower and 140 lb-ft of torque. That’s enough for the MX-5 to feel fun and playful, but there’s a potential issue, too: The rod bearings aren’t keyed. In other words, those bearings don’t have a notch that prevents them from spinning, and lots of owners report rod knock that kills their engines.
“The bearing shells were stacked on top of each other, both halves of the bearing on one side. The crank was beat to hell and probably can’t be ground. On the good rods, I noticed that there was no key on the bearings to prevent spinning.”
The top comment in the thread above put it this way: “Yep, the classic NC knock of death. I see a 2.5 swap in your future.”
This brings us back to the solution phase of the problem. Ford’s 2.5-liter four-cylinder, again, co-developed with Mazda and just a rebadged version of the Mazda-built 2.5-liter “MZR,” bolts in where the 2.0-liter once did. I don’t mean that it’s kind of similar and requires minimal cutting and hacking either. I mean it literally bolts up to the gearbox and fits in the engine bay with zero hacking.
One person who did exactly this swap and posted on Reddit about it described it this way.
“This motor is close to identical to the 2.0 that came in the car. The 2.5 is just about half an inch taller overall. Otherwise, the swap consists of essentially moving all your accessories from 2.0->2.5, and adding friction washers to the cams and crank pulley.”
It’s worth noting that the 2.5-liter from the Ford Fusion was designed to work in a front-wheel drive application. To that end, those who do this swap do have to swap a few parts from one car to the other.
That includes using the oil pan from the Miata engine on the Ford engine (to fit, this requires moving the 2.5’s balance shaft assembly, which would in theory lead to increased vibrations) and swapping over the motor mounts to 2.5-liter ones that’ll let the engine sit a little lower. Seriously, this is such a popular upgrade for Miata users that there are countless threads, explainers, and DIY posts on it.
Did I mention that it’s budget-friendly too? Miata engines from this generation regularly cost around $2,000 or more. Keep in mind that using one would result in the same power output and potentially the same issues with the bearings.
On the flip side, Ford Fusion engines cost under $500 and that includes shipping in some cases. I cannot say this loud enough, you’re essentially saving significant cash while adding power, and what’s more, these 2.5-liter MZRs are borderline unkillable.
Brett Becker, who did a thorough writeup on how he conducted this swap, says the Ford engines are the way to go if you’re on a budget:
Bear in mind, engines that come out of Mazdas are generally more expensive than those that come out of Fords. I’m told it’s because of higher-quality internal parts, but it just as easily could be due to greater numbers of Fords in salvage yards.
How much of an upgrade is this really you ask? That extra half a liter of displacement only provides a small bump in overall horsepower. The Ford engine makes just 175 horsepower at its peak but it also develops 170 lb-ft of torque. Five more ponies and 40 lb-ft more torque. That’s nothing to sneeze at.
One owner in the last video embedded below estimates that it makes 40 or 50 more horsepower lower in the rev range too (i.e. it has significantly more low-end torque). That’s significant, and the additional torque only adds to the car’s fun-factor. Here’s a dyno pull with a stock Miata.
Owners with the 2.5-liter report achieving over 200 horsepower with very few mods.
Oh and don’t forget that it’s tunable. (Apparently you can just use the Miata’s stock 2.0-liter ECU, though most will tune that to match the 2.5).
Don’t get me wrong, it’s not like there’s a ton of hidden horsepower in this Ford engine. Tuning enables the owner to add things like no-lift shifting, launch control, and more.
I’ve never really wanted to own a Miata, I can’t really fit in them super well, but now… I might be shopping for one with a serious rod knock. If you want one that’s already finished, this one is on sale for $10,000.
If an mzr from a fusion is going into this already great car, could it be made better by feeding it the fusion’s favorite flammable feastings, 87 octane? The cost/mile will drop significantly, even at 35-ish mpg.
Has anyone experimented with this possibility, whether the ecu from the miata is reconfig’d for swilling the peoples freedom juice, or using the fusions ecu, which is already accustomed to such spirits, or just run the miata ecu and hope for the best?
I am very curious, as i am aiming to part out or sell an s60r for this to happen somehow in my future, but would prefer to get away from the 91+ octane that my turbo vo-vo’s drink, as both my wife and i each drive 30K+/year, and these $4+ fuel prices are rough.
Thanks!
How easily would the turbo 2.0, also from the Fusion, swap into the NC? While not exactly a paragon of reliability, I believe it’s from the same engine family. I’d imagine they’re also fairly easy to locate, reasonably priced and tunable. Ford made a bunch of them and used them in multiple vehicles.
Egads. The last thing I needed with my NC was more torque and HP.
What about sticking this in a NA?
Let’s face it the doorhandles alone on the NA make it the only choice.
This isn’t since crazy news, this is people realizing what parts cross over. Ford and Mazda made a lot of stuff together. The Miata engine is based upon the same architecture as the fusion and focus engines. There is a reason the 2.0 Ecoboost bolts up. It’s the computer and everything else working right that’s the hard part. That Miata engine only makes 10hp more than the 2.0 did in the focus. Ford used the Mazda architecture for its cars until 2015. The focus st kept the same engine and was licensed separately until the mk3 focus was gone.