Some Lunatics Are Making A Kit To Swap A Dirt-Cheap Flat-Six Into A Subaru BRZ

Whether you call it a Subaru BRZ, a Scion FR-S, a Toyota 86, or a Toyota GT86, the first generation of Toyobaru sports coupes is currently an undeniable bargain. With enormous aftermarket support, the practicality of a fold-down rear seat, and pricing for early examples often falling under $10,000, it’s an awfully tempting proposition for a project. But what if the two-liter flat-four isn’t enough for you?

On paper, it’s a fine engine. Not spectacular, not abysmal, just fine. It’s happy to spin all the way up to 7,400 RPM, and its peak output of 200 horsepower means zero to 60 mph in a shade over six seconds with a manual gearbox, but it has a few issues. Some are easily solvable, some aren’t. The dip in the torque band around 4,000 RPM is noticeable, but can be massaged out with a header and a tune. Valvetrain-related issues and their resulting complications can’t. Rocker arm failure can cause serious engine damage, and a valve spring recall on very early cars required careful use of RTV silicone gasket-maker by technicians, else bits of excess silicone could break off, clog the oiling circuit, and cause engine failure.

So, if you have one of these cars with a bunk engine and don’t want to throw a stock replacement in, what would you do? While the 2.4-liter engine from a second-generation car, a Honda K-Series, or even a GM LS-based V8 are all tempting, Chase Bays has thrown a wildcard into the mix by developing a kit to swap a flat-six into an FR-S, BRZ, or Toyota 86. How marvellously exotic.

It all starts with some rather good news: The flat-sixes in question are cheap. We’re talking about the Subaru EZ30R and EZ36 flat-sixes, engines that made their way into a huge number of Legacies, Outbacks, and Tribecas. If you’re staying naturally aspirated, the EZ36 is the more tempting choice. Displacing 3.6 liters, it originally put out 256 horsepower and 247 lb.-ft. of torque on regular 87-octane gasoline. Oh, and it makes eargasmic noises with the right exhaust setup.

These days, a good, reasonably low-mileage EZ36D 3.6-liter flat-six is worth all of about $1,500. They’re so stout, demand for second-hand replacement engines just really isn’t there. Considering a brand new 2.4-liter second-generation flat-four costs about $8,145 without ancillaries, that’s pretty attractive. However, the cost of the kit does add up quickly, and all the stuff to put an EZ36D in a BRZ or FR-S will run you $7,999.

That’s a lot of money, but the Chase Bays kit does include a lot of stuff. The big one is the electronics: a Link G5 standalone ECU with a pre-loaded base tune, a harness, a harness adapter to tie into the stock body harness, a standalone intake air temperature sensor, and a Bosch Motorsport oil pressure and temperature sensor. This big suite of gizmos means that not only will the swap run and drive on the base tune, but every factory function of your Toyobaru will work. All the buttons, all the gauges, the lot.

Beyond that, the kit includes an entire fuel system with Radium rails and a 450 lph E85-compatible Walbro fuel pump, all the cooling system plumbing you need, a proper oil cooler, a 6-2-1 header, an intake, and a clutch delay valve so you don’t leave your gearbox on the pavement with hard shifting should you decide that natural aspiration isn’t enough. Weirdly, a baffled oil pan isn’t included, but it’s highly recommended. NAS Performance has a kit for $300 that should do the job nicely.

From there, installation sounds like an absolute breeze. The EZ36 engine mounts line up perfectly with the stock Toyobaru subframe. The factory transmission bolts right up to the back of the flat-six, and Toyobaru clutches and flywheels are compatible with the six-cylinder engine. In theory, you aren’t looking at any fabrication, and the extra two cylinders only come with a weight penalty of 24 pounds over the standard BRZ engine.

So what’s the headroom on one of these engines, assuming you don’t want to go down the rabbit hole of turbocharging? Chase Bays made 270 wheel horsepower on E85 fuel in its naturally aspirated development car, which is right in the ballpark of an E46 BMW M3, and that’s not a slow car. Oh, and did I mention that an uncorked Subaru flat-six sounds as glorious as you’d expect? It’s a note you simply wouldn’t get out of an LS or a Gen 2 Toyobaru’s FA24D.

Granted, this swap isn’t for everyone. All-in with a clutch, flywheel, fluids, fresh engine mounts, preventative maintenance on the flat-six, and a bit of dyno time to get a proper custom tune dialled in, you’re probably looking at between $11,000 and $13,000 depending on how far you want to go. The flipside is that with how cheap good rolling chassis are, an EZ36-swapped first-generation BRZ would be a serious ripper for about $20,000 all-in. Better still, there aren’t really any gotchas with an EZ36, so provided it’s been taken care of, it should provide miles of fun to come. There is one catch, though: Chase Bays needs ten pre-orders to get bulk manufacturing going. Are you feeling bold?

Top graphic image: Subaru, Chase Bays