Miata Engine Swap Guide

The Mazda Miata (often called the MX-5) has long been celebrated for its light weight, rear-wheel drive layout, and superb handling. This little roadster’s balance and cornering prowess have won over countless enthusiasts. But as fun as it is from the factory, many drivers eventually crave more power, especially if they’re hitting track days or trying their hand at drifting. That’s when engine swaps come into the picture, ranging from simple four-cylinder replacements to epic V8 transplants. Of course, bigger (and often heavier) engines bring bigger costs, plus added complexity, so preparation and research are vital.

Forced Induction vs. Engine Swaps

Before tearing out the old engine, many Miata owners try forced induction, turbocharging or supercharging the stock BP engine can net an easy 200–250 wheel horsepower. It’s a straightforward way to get a big kick without heavily modifying the entire car. However, if your stock motor has seen better days, or you simply want a unique sound or feel (like a smooth V6 or a rumbling LS V8), an engine swap can become incredibly appealing.

Staying Stock: The Original BP Engine

Miatas from the first two generations (NA and NB) came with 1.6L or 1.8L BP engines. Power ranges from about 110 hp in the 1.6 to around 140 hp in the 1.8. While that can be enough for a new driver learning the ropes, track enthusiasts and drifters often outgrow the modest output pretty quickly. The big upside of keeping the BP engine is simplicity: it’s inexpensive, parts are everywhere, and it teaches you how to carry speed through corners. But once you want more than 200 horsepower, you’ll be spending serious money on a built BP that still might not meet your lofty power goals.

Forced Induction on the BP Engine (Turbo / Supercharger)

Turbocharging or supercharging the factory BP engine deserves a quick mention because a lot of folks see it as a stepping stone before committing to a full-blown engine swap.

A turbo kit can reliably deliver 200–250 whp if you don’t scrimp on supporting upgrades like cooling and fueling. You can try cheaper “eBay kits,” but you risk reliability headaches, especially if you plan to push the car on the track. Meanwhile, superchargers can hit 180–220 whp, typically with a smoother power band but a bit more limited top-end potential. If 200–250 whp satisfies your needs, a forced-induction BP might be all you ever need. But if you’re chasing more extreme power or a completely different driving experience, swapping is the next big step.

Engine Swap Options

Engine swaps span everything from budget-friendly four-cylinder replacements to the famous GM LS V8. Your choice hinges on power goals, budget, and whether you want to preserve (or totally transform) the Miata’s original character.

GM Ecotec (2.2L/2.4L)

These aluminum four-cylinders from GM are cheap and offer decent torque, typically delivering around 170–200 whp without forced induction. They may feel slightly unrefined compared to a Honda K-series, but the low cost of the engine itself is hard to beat. You’ll still need custom mounts, wiring, and a stand-alone ECU solution, but the overall budget often stays below what you’d spend on a K-series swap.

Honda K-Series (K20/K24)

The Honda K-series is beloved for its reliability, high-revving nature, and massive aftermarket support. In a Miata, a stock K24 can make 200–220 whp with intake, exhaust, and a good tune. Build it further, and you can exceed 300 whp without too much trouble. Companies like KPower (KMiata) offer kits that streamline the swap, but be ready to invest $7k–$10k or more by the time you’re done. You also need to consider transmission upgrades (like an NB 6-speed or a BMW box) if you’re aiming well above 220–250 whp.

Built BP or B-Swaps

Some enthusiasts prefer to keep everything “Mazda” by strengthening and tuning the original BP engine. You can hit 160–185 whp naturally aspirated with cams, a higher compression build, or even individual throttle bodies. But it’s not unusual for these builds to cost $5k–$6k and still come up short if you’re dreaming of 250+ horsepower. For purists, though, a fully built BP with ITBs is a sweet-sounding labor of love.

V6 Swaps

If you want more grunt without the heft of a V8, a V6 could be the sweet spot. Options include GM’s LFX (3.6L) or Honda’s J-series. Expect roughly 250–320 whp in stock form, along with a unique exhaust note. V6 swaps are less common, so you may need to do more custom work or source less mainstream kits. The payoff can be a lighter front end than a typical V8 and a smoother power delivery than a turbo four-cylinder.

V8 Swaps (LS, LT, etc.)

The legendary LS swap is the “stuff a big engine in a small chassis” formula. With an LS1 or LS3, you’re looking at 300–500+ whp, plus big torque that launches this featherweight car out of corners like a rocket. Companies like Flyin’ Miata or V8Roadsters offer kits, but expect to spend $15k–$20k to do it right, partly because you’ll need to upgrade the transmission (commonly a T56), suspension, brakes, and differential to manage all that extra power. Maintenance can also get tricky since an LS fills up the engine bay, but the raw performance and jaw-dropping engine note are tough to beat.

Costs, Complexity, and What to Expect

Swaps involve a lot more than just an engine and transmission. You’ll need new mounts, an appropriate driveshaft, custom exhaust, better cooling, upgraded fueling, and stand-alone or reworked electronics. Even if you handle most of the labor yourself, plan on unexpected hiccups: you might blow a coolant hose on the dyno or run into wiring gremlins that require extra troubleshooting. If you pay for professional labor, budget can shoot up by several thousand dollars fast.

Special Note: ND (2016+) Miata Swaps

The newer Miata (ND) uses advanced electronic systems, from drive-by-wire throttle to CAN-bus sensors, making engine swaps more complicated. Flyin’ Miata created an LS-based kit, but it can cost $50k–$60k if you’re fully committed (including the cost of the car). V8Roadsters has tinkered with a GM LFX V6 as well, though it’s still a steep project. Most ND owners find it cheaper and simpler to add forced induction to the Skyactiv engine rather than fully swapping it out.

Which Swap is Right for You?

• Under $5k: Go for a used turbo setup on the BP or a mild BP rebuild.
• $7k–$10k: A straightforward K-series swap or a high-quality turbo kit with all the trimmings.
• $10k–$15k: A more refined K-series build or a simpler V6 swap, plus upgrades like a limited-slip diff and better brakes.
• $15k+: An LS-based V8 conversion, a heavily built K-series pushing 300+ whp, or an LFX V6 with major chassis and brake enhancements.
• Full Track Monster: A big-power LS (maybe even supercharged), Ford 8.8 differential, roll cage, wide tires, and a mountain of supporting mods.

Real-World Driving Impressions

A mild turbo BP still feels very “Miata,” just with an extra shot of adrenaline. The K-series turns the car into a high-revving track star that can still feel balanced, though it’s not the cheapest route. An LS swap, on the other hand, delivers a thunderous V8 experience with crazy acceleration, just be prepared for wheelspin and the extra weight of a heavier transmission. Meanwhile, a well-sorted V6 can strike a middle ground, though you may have to blaze your own trail on certain parts of the install.

Careful planning and a realistic budget are crucial. Figure out how much power you truly want and whether you’re ready to pay for all the supporting mods, bigger brakes, stiffer suspension, better cooling, and so on. Tuning is another biggie; most swaps aren’t plug-and-play, so you’ll likely spend time on a dyno to iron out any quirks. Don’t forget to tap into Miata forums and swap-specific communities, as they’re packed with tips, troubleshooting advice, and moral support.

All told, a Miata’s magic lies in its lightweight and nimble feel. Whether you stick a turbo on the stock engine or cram in a V8, aim to preserve that classic chassis balance as much as you can. Done right, you’ll end up with a truly personalized performance machine that stands out at the track, on the street, or wherever your next adventure takes you.