2013 BRZ FA24 Swap

This write-up assumes you're using a 2013 through 2016 FR-S / BRZ as your chassis, and you want to swap an FA24 from a GR86 / BRZ, without using a Standalone ECU. A standalone ECU makes this swap both simpler and more expensive. 

Shopping List

• FA24D Engine

  • EBay, FB Marketplace.

  • Look for running video and pictures of the donor. $4-5k price range should be attainable.

  • Fully Accessorized is a plus, but alternator and A/C compressor are not used so not a big deal if they are missing, make sure it's not missing the vacuum pump

• RS Motors Kit

  • This kit includes 4 camshaft wheels, and crankshaft position sensor mount

  • Ron @ +1 (952) 707-0100, or ron@rsmotorsinc.com

  • Ordering method may change soon to Hachi Electronics

• Hachi Electronics Wiring Harness Adapter Kit

  • https://hachielectronics.com/products/fa24-engine-swap-harness - Select the year of the harness being used

• 2015-16 Engine Wiring Harness (if 2013-14) OR coil pack adapter kit

  • Car-part.com, eBay, or about $350 from your local subaru dealer (recommended)

  • Connectors if splicing 2013-14 Harness: https://www.icefabrication.com/product/coil-pack-connector-upgrade-to-2015/

  • Adapters: https://www.fastwrx.com/products/otl-coil-pack-adapters-2013-2016-brz

• Prius Crank Position Sensor

  • Toyota Part no. 90919-05087 - e.g: https://autoparts.toyota.com/products/product/sensor-crank-position-9091905087

THE SWAP

With the parts we need off the FA20 and the FA24 prepped to receive the necessary modifications, we can start the swap. Continue here once you have all your parts from RS motors, and your Hachi Electronics harness adapters.

DI CONTROLLER MOUNTING

The FA24 DI Controller isn't mounted to the engine and won't be used. We have to transfer the one from the FA20. There are 3 approaches to mounting the controller onto the FA24.

OPTION 1

We can mount it using without using the fuel rail cover at all by mounting the existing DI bracket onto the block. This will leave it with the ability to pivot so it also means having to fabricate a small bracket to avoid movement on the controller, and also potentially adding a grounding strap to the remaining hole. Looks something like this:

ENGINE MOUNTS

The engine mounts from the FA24 use a thicker stud than the FA20 mounts. There are two approaches to this:

OPTION 1

Modify the FA20 engine mount by cutting off the small block that protrudes from it and using a shorter bolt on that hole to attach it to the engine. This is the route I went. My FA24 came with its engine mounts attached, so I was able to use the shorter bolts from it (fresher hardware anyway). Here is the before/after modified engine mounts:

After smoothing things out, cleaning, and a quick spray of high-heat engine enamel, your mounts are ready to bolt onto your FA24. Attach to the engine and torque to 47 Nm (34.7 ft-lbs).

OPTION 2

Widen the slot on the FA20 subframe to accommodate the FA24 engine mount stud, and source a matching nut. I did not want to attempt this as any mistake could mean replacing the front subframe.

CAMSHAFT TIMING WHEELS

The Cam timing wheels are different in the way they transmit signal and the timing itself (6deg difference). They must be swapped for new ones included in the RS Motors Swap Kit.
  

A few warnings before proceeding:

Avoid using impact tools anywhere inside the timing chain area/housing. Use normal hand tools to avoid metal particles from bolts and sockets from getting into the engine/oil pan.

It is not necessary to remove the timing chain for the following procedure. This can all be done without the risk of changing the timing.

When cleaning sealant residue, take off the majority of the gunk with a plastic utility blade (not a flathead screwdriver) to avoid scratching the mating surface. If a metal utility blade is used, be very careful not to dig in with the corners. Solvents such as Brake cleaner or acetone can help, but only use this on the cover and not the engine side. There is sealant used on some of the seams on the engine side and you do not want to dissolve it. For hard to reach crevices and grooves, use a brass wire brush to avoid marring the surface.

Firstly, remove the timing cover. Make sure every bolt is removed (27x 12mm and  5x 10mm, 32 total) before prying from the designated pry spots. Ensure you didn't lose any O-rings when taking off the cover. Clean both the engine and timing cover mating surfaces of any sealant. Try to scrape the sealant off on the engine side on the side of the engine closest to the floor. Rotate the engine on your engine stand and always scrape the side closest to the floor. This way sealant falls to the floor instead of into the oil pan, tensioners, chain, sprockets, etc. As you remove the sealant, make note and mark with a Sharpie the interior bolt holes that need a ring of sealant around them. 

To remove the cam timing wheels, you'll need snap ring pliers to remove the C-clips in the center of each wheel. These will be reused. Once they're removed, remove the 3 E-Torx (E16) bolts holding the cam wheel. Some movement in the cam sprocket is normal. Remove the timing wheel gently, replace with the RS Motors wheel for the appropriate position. Replace the other 3 wheels. Torque the 12 bolts to 18nm (13.3 ft-lbs). (Page 14 in the manual below)

Apply sealant to the timing cover. Be as consistent as possible and try to strike a balance between having enough sealant, and not overdoing it to the point that some sealant can detach and fall into the oil pan. In the next 5 minutes (as if it's not stressful enough), carefully and steadily install the timing cover. Having another person stabilize the cover as you mate it to the engine is helpful to prevent smearing the sealant too much. I've linked below to the Service Manual. I encourage reviewing it. 

Depending on the sealant you use, you may have to wait to put oil in the engine until the specified curing period for your sealant. Some require a full 24hr before they're able to come in contact with fluids.

Reference:

Engine Repair Manual: https://drive.google.com/file/d/1Tehxm5DCRZCZ7YBQdBlXt4tYPjYDYFPK/view (Pages 119 -126)

Subaru uses this sealant: https://www.amazon.com/THREE-BOND-Gasket-Maker-performance/dp/B06XJ98SMP, but Permatex Ultra Grey will work just fine.

YOU'RE DONE WITH THE MOST STRESSFUL PART OF THIS SWAP!

FUEL PRESSURE SENSOR

The 2013-16 runs at a higher fuel pressure than the FA24 is capable of producing. This means the sensor is different. A custom sensor and connector is needed. This is necessary because Ecutek unfortunately doesn’t have the HPFP control tables unlocked for tuning. The RS Motors Swap kit comes with a new fuel pressure sensor and connector that needs to be spliced onto your FA20 harness. Unscrew the old sensor and screw in the new one. If you need a replacement sensor, here's the OEM one: https://www.subarupartspro.com/oem-parts/subaru-pressure-sensor-16628aa020

FUEL PRESSURE CONNECTOR

We need to splice the fuel pressure connector. I used shrink-wrap butt connectors with extra shrink wrap on top to weatherproof them. The pigtail and connector sent by RS motors should have color matched wires for easy reference. 

CRANKSHAFT POSITION SENSOR

The crank position sensor needs to be swapped due to the differences in the crank reluctor wheel between both engines (pictured below). The Prius crank sensor is longer and has the correct length to read the FA24 crank reluctor wheel. However, it does not fit the sensor mount. Remove it and replace it with your RS Motors CPS mount, then install your new, longer crank sensor along with the Hachi Electronics adapter. 

Note: This section of the guide has been updated on 3/6/2025 which is why I do not have installed pictures of the newest components from the RS Motors Kit. 

Tip: Wait to put the sensor onto the mount until you're ready to start connecting your harness. It's a bit tight and it's easier to plug the sensor in before bolting it on.

SENSORS

There are 3 other sensors that are different from the FA20:

• Evap Purge Solenoid - Under the Intake manifold, blue connector on the harness

• Coolant Temp - on the water pipe that runs across the top of the short block, near the passenger side fuel rail
  Tip: The coolant temp connector and the knock sensor connector are the same shape. The one with the shorter wires is for the knock sensor. Don't mix these up or the car won't start and the coolant temp gauge will show maxed out. Ask me how I know. 

• Oil Temp - on the timing cover, driver's side

The Hachi Electronics Kit makes these sensors Plug and Play. You just connect the adapters to your FA20 harness so you can connect to the sensors on the FA24.

COOLANT HOSES (A/T DONOR ENGINE)

There are some coolant hoses and tubes that need to be addressed if your engine came from a car with an Automatic Transmission. Skip this part if your engine came from a Manual Transmission car. There are 2 tubes that end up going nowhere behind the driver side cylinder head. The upper hose is supposed to go back to the transmission, and the lower tube is supposed to have a hose coming back from the transmission. Loop these together, or block off both the port on the upper coolant passage and the lower pipe. Alternatively, you can get the MT pipes and swap them in: https://parts.subaru.com/p/Subaru__/Pipe-Complete-Water/105787266/14050AB510.html

ENGINE HARNESS ROUTING

There are some challenges routing the engine harness, more specifically by the front driver's side of the engine. To get to all the connections, I had to route the AVCS Cam Sensor wiring behind the oil filter heat exchanger hoses for better reach, and I had to slip the Camshaft Position Sensor (CPS) wiring between the High Pressure Fuel Pump mounting bracket, and the heat exchanger. For the connector to fit through, I had to remove the CPS itself to allow the connectors to fit through to the side of the timing cover. I also had to connect the upper CPS to the connector before reinserting it for a proper fit. 

Tip: If you do not mind not using the fuel rail cover for the driver's side of the engine, it's possible to remove two of the cast brackets that are used to hold it up in order to have more room to route the engine harness. Loosening the fuel hard line is necessary to get to one of the bolts. I've done that after putting together this guide.

Another small issue will be one of the ground eyelets for the harness. There's a new bracket you'll have to trim, bend, or angle to get both harness ground eyelets bolted down. 

ALTERNATOR

The alternator from the FA20 must be used on the FA24, as it hi/lo control circuit is a totally different language, as well as the supplied amperage. The challenge here is that the mounting holes for the FA20 alternator bracket do not line up with the FA24's mounting tabs. Modification of the FA20 mount is necessary until a full replacement is available in a kit. RS Motors currently offers to modify the FA20 alternator mount to line up with 3 of the holes on the FA24. Install the modified bracket and your FA20 alternator. The holes used for the installation are the left one, and the two on top of the block. The hole on the right will not line up. 

Transfer your FA20 Alternator onto the FA24 alternator mount. All but one hole will line up. I do not have pictures of this setup, but it has been the prevailing advice with current swaps.

FINAL ASSEMBLY

Mount the rest of the accessories, install the throttle body (the FA24 throttle body is bigger, but it is possible to stretch the FA20 intake tube to fit. I used a 90 degree pick to pull it around and get it over the TB lip), accessory belt, hoses, connect remaining sensors. Once it's all together, you're ready to install your FA24.

Some helpful torque specs:

• Flywheel bolts - 88nm (65 ft-lb)

• Pressure plate bolts - 25nm (18.4 ft-lb)

• Intake Manifold - 22 Nm (16 ft-lb)

• Throttle Body - 7.5 Nm (5.5 ft-lb) 

• Engine Mount nuts (FA20 mounts) - 41 Nm (30 ft-lb)

• Alternator Mount and A/C Compressor - 24 Nm (18 ft-lb)

• Crank Pulley - 130 Nm (96 ft-lb)

• All other Pulleys - 39 Nm (29 ft-lb)