Dropping an FA24 Into Your Older WRX: What the Swap Actually Costs (And What Nobody Tells You)

Every few months, the swap conversation resurfaces on the forums. Someone posts a thread asking whether it's realistic to pull an FA24 from a 2022+ WRX and drop it into a 2015–2021 chassis. The replies are always a mix of genuine enthusiasm, hard-won warnings, and at least one person who swears they've priced it out and it totally makes sense. Spoiler: it usually doesn't — at least not the way most people imagine it.

That said, it has been done. And the guys who've done it have some things to say.

What's the FA24 Even Bringing to the Table?

Before we get into the logistics, it's worth understanding why anyone wants this engine in the first place. The FA24 is a 2.4-liter turbocharged flat-four that debuted in the 2022 WRX. It replaces the FA20 with a bigger bore, revised porting, and a more sophisticated fuel injection setup. In stock form it makes 271 horsepower — not earth-shattering — but the architecture has significantly more headroom for boost. Tuners who've worked with it on the 2022+ platform have pushed it to 400+ whp on supporting mods, which is a territory the FA20 reaches only with considerably more drama.

So the appeal is real. The question is whether the path to getting there makes any financial sense when you're starting from a 2015–2021 WRX.

The Fitment Reality

Here's where things get honest fast. The FA24 and FA20 share the same basic engine family, and on paper they look compatible. In practice, the differences stack up quickly.

Mike T., a builder out of Denver who completed an FA24 swap into a 2018 WRX last year, puts it plainly: "The block physically fits in the bay. That's about where the easy part ends." The engine mounts require modification or custom fabrication. The FA24 uses a different turbocharger inlet configuration, so the stock intake path from the older car doesn't connect cleanly. Coolant and oil line routing differs enough that you're either sourcing OEM lines from the donor car or having custom lines made.

Then there's the electronics. The FA24's engine management is tightly integrated with the 2022+ chassis's CAN bus architecture. Dropping it into a pre-2022 car means you're either doing a full ECU swap and wiring harness transplant — which is a project in itself — or you're working with an aftermarket standalone ECU like a Haltech or AEM Infinity. Both paths add cost and complexity.

"I went the standalone route," Mike says. "That was another $2,800 on top of everything else, plus tune time."

Breaking Down the Real Numbers

Let's talk dollars, because that's where most swap dreams quietly die.

A used FA24 pulled from a wrecked 2022–2024 WRX is currently running anywhere from $4,500 to $7,500 depending on mileage and what ancillaries are included. That's the long block. If you want the turbo, manifold, and supporting hardware, budget closer to the top of that range or higher.

Labor at a shop that actually knows what they're doing — and you want one that does — is going to run you 40 to 60 hours minimum. At $125–$175/hour in most metro areas, you're looking at $5,000 to $10,500 in labor before a single test drive.

Add in the standalone ECU, custom fabrication work, a base tune, new engine mounts, updated cooling components, and the miscellaneous hardware you'll burn through, and a realistic all-in number lands somewhere between $15,000 and $22,000 for a well-executed swap on a pre-2022 chassis.

For context, a clean 2022 WRX with low miles can be had for $30,000–$34,000 right now. A 2023 with some dealer markup is still in reach for many buyers. That math is uncomfortable.

When It Actually Makes Sense

So is the FA24 swap ever the right call? A few scenarios where it pencils out:

You already own a heavily modified pre-2022 chassis. If you've got $8,000 in suspension, $3,000 in brakes, and a fully built interior, you're not walking away from that car. Swapping the engine preserves the investment you've already made in the platform.

You're building a dedicated track or time-attack car. Resale value stops mattering. The performance ceiling of the FA24 justifies the cost if you're chasing lap times and the car lives on a trailer half the year.

You source a low-mile donor car and do a significant portion of the work yourself. If you're mechanically capable, have a lift, and can handle the ECU work, the labor cost drops dramatically. A few builders in the community have gotten their total outlay under $10,000 this way — though it took months.

What About Resale?

Bluntly: a swapped car is almost always worth less than a stock one of comparable age and mileage. Buyers get nervous. They don't know if the swap was done right, and they can't easily verify it. The exception is the track/race car market, where buyers understand modified vehicles and evaluate them differently.

If you're planning to sell the car eventually, the FA24 swap is a financial loss. If you're planning to keep it and drive it hard, that calculus changes.

The Bottom Line

The FA24 swap is technically feasible. The engine fits — with work. The performance gains are legitimate. But this is not a budget-friendly path to more power, and anyone who tells you otherwise is either glossing over the details or got very lucky with their donor parts.

If you're on a budget and want more grunt from your older WRX, a built FA20 with a proper turbo upgrade and E30 tune will get you to 350+ whp for considerably less money and dramatically less complexity. The FA24 swap is a dream build — just make sure you're going in with open eyes and a realistic budget.