How to 2AR Swap Your SW20 MR2

Written By Max Sehic

This guide provides info on swapping a 2AR-FE into an SW20 MR2. The 2AR-FE has various configurations for different power levels, but we'll focus on using the stock ECU and a stock 2AR-FE in the SW20. For more details on other configurations, visit FrankensteinMotorworks on YouTube. A shopping list is also provided at the bottom of this page.

A BAR legal 2AR-FE guide is also available. For those who are interested in getting a California legal setup running, please read this guide instead.

ENGINE

The 2AR-FE came in the Toyota Camry, RAV4, and Scion tC in the USDM. You may use any 2AR-FE from any vehicle. There are some minuscule external differences during specific year ranges, but there are no internal differences between 2AR-FEs.

2014 Scion tC 2AR-FE

To get the 2AR-FE into the SW20 chassis, you can use the Frankenstein Motorworks 2AR-FE SW20 Motor Mount. This mount bolts to the front of the motor on the timing cover and is a full replacement of the stock 2AR-FE mount. You will use the 3 other stock transmission mounts.

The gold circled bolts are torqued to 41 ft-lbs.

The blue circled bolt gets torqued to 15 ft-lbs.

The rubber isolator that bolts into the chassis is torqued to 58 ft-lbs.

The nuts that bolt to the studs into the isolator are torqued to 45 ft-lbs.

Drivetrain

The stock MR2 drivetrain can be bolted and used with the 2AR. Here is a list of hardware needed per transmission as well as the clutch kit info. One of the holes on the 2AR will need to be threaded as shown here in the blue circle in the second image.

This hole may be threadable outright or in need of a threaded insert, such as a helicoil or timesert. This will depend on the block you get.

1991-1992 E153 Hardware

  • 2 x M12x1.25mm 55mm

  • 1 x M12x1.25mm 70mm

  • 1 x M10x1.25mm 35mm

1993+ E153 Hardware

  • 3 x M12x1.25mm 55mm

  • 1 x M12x1.25mm 70mm

  • 3 x M10x1.25mm 35mm

E351 Hardware

  • 1 x M12x1.25mm 70mm

  • 2 x M12x1.25mm 55mm

  • 1 x M10x1.25mm 50mm

  • 1 x M10x1.25mm 60mm

  • 1 x M10x1.25mm 35mm

1991-1992 S54 Hardware (Hole under the starter needs to be enlarged to 12mm)

  • 1 x M12x1.25mm 55mm

  • 1 x M12x1.25mm 70mm

  • 1 x M10x1.25mm 35mm

Torque

  • M12 bolts to 47 ft-lbs

  • M10 bolts to 34 ft-lbs

Note, these hardware lengths are based on the 2GR-FE hardware sizing. However, I used the same bolt lengths from the 2GR-FE with the 2AR-FE. There is a chance however these lengths are wrong and/or your transmission is not listed. If that is the case, then use a depth gauge to measure the bolt hole depth. Round down to the nearest 5mm interval then subtract an additional 5mm, use that number to order correct length bolts. If more precise hardware is found, I will update this guide.

Recommended Flywheels

  • Stock 2AR-FE Flywheel (Toyota PN 13405-28020)

    • Heavy, slower revving, easier clutch engagement

  • ACT XACT Prolite (ACT PN 600390)

    • Lighter, faster revving, and shifting slightly more difficult clutch control

      Note: There are other flywheels available for the 2AR-FE however these two are known good quality units.

Recommended Clutches

  • E series (E153, E350, E351, etc.)

    • Frankenstein Motorworks E series clutch kit, available in either organic or ceramic material.

      • Organic has more than enough clamping force for a naturally aspirated 2AR-FE build.

      • Ceramic is slightly more difficult to actuate, though this clutch has a marcel spring which helps significantly.

  • S series (S54, etc.)

    • South Bend K16062-16073-HD-O

      • This is a single kit. This kit contains a clutch disc with the S series spline and a pressure plate that matches the E series pattern.

    • Piece together your choice of an S54 clutch disc and E series pressure plate, both rated for 250lb*ft or higher.

Clutch Hardware

  • Flywheel bolts: ARP 103-2801 or Toyota 90105-12322

  • Pressure plate: ARP 103-2201 or Toyota 90119-08079

Axles

  • S series (S54, etc.)

    • Standard SW20 NA axles

  • Wide-diff E series (E53, E153, E250, etc.)

    • Standard SW20 Turbo axles

    • Right side axle carrier bearing bracket currently unknown. Check back later.

  • Narrow-diff E series (E350, E351, etc.)

    • Follow Alex Wilhelm’s guide on axle setup for E351/2gr-fe/SW20

    • Right side axle carrier bearing bracket currently unknown. Check back later.

Note, it seems all aftermarket throwout bearings are not worth using, I would highly recommend buying a new OEM unit from Toyota.

Fuel System

The 2AR-FE shares a similar returnless style fuel system as the 2GR-FE. The same solution that is used with the 2GR-FE swap in the SW20 can be used with the 2AR-FE. Wilhelm Raceworks makes a good fuel system kit that converts the system over to a returnless system.

Some 2AR-FEs will come with a snipped OEM fuel hose. I cut back the outer rubber layer, left the pressed-on nylon hose, and slid a 5/16” EFI fuel hose over the nylon hose (Shown in gold).

For those who buy Wilhelm Raceweork’s setup, unfortunately, the included hardline adapter fitting does not fit the 2AR fuel rail. EARLS 751156ERL will be needed in order to adapt the fuel rail to AN6. With this fitting, the OEM fitting is replaced entirely, and the rest of Wilhelm Racework’s kit can be installed.

For those who get a 2AR without this OEM fitting, and would like to run the OEM fitting, the P/N is Toyota 23901-36041.

The stock MR2 fuel pumps should be fine for the lower power levels of the 2AR-FE, but for those planning on making bigger power with your 2AR, you will need a larger fuel pump.

Electrical

Engine Harness

For wiring harness work I’d recommend going to Woodsport for your wiring needs. Woodsport offers a patch harness that is a direct plug-and-play harness called the WASP harness that allows the use of a stock Scion tC harness with no modification.

This patch harness does not require you to ship out your harness. Any questions about this patch harness should be directed to Paul Woods at Woodsport.

If you would like to complete the wiring yourself, the Scion tC wiring diagram is available here, you can modify an existing Scion tC wiring harness or build one from scratch following the diagram.

*A small modification will need to be done to a tC harness if you use the AC setup from this guide. Said modification is noted in the AC section.

As of recently, it seems the Woodsport WASP harness for the 2AR is no longer available. You will have to create your own patch harness or modify an existing 2AR-FE harness to suit your needs.

Tachometer

You will need to convert your tachometer to a 12V system. This requires one resistor to be changed on the tachometer assembly. Replacing the capacitors is recommended too. Frankenstein Motorworks sells a little kit that comes with the needed resistor and capacitor.

Marc has a good video showing how to change these out.

Throttle Pedal

You will also need to change the old and ancient cable throttle pedal to a new drive-by-wire pedal. FrankensteinMotorworks has us covered again here. The wiring for the pedal will be included in the WASP harness from Woodsport.

If you opt for the BRZ or IS Sport (pictured) pedal face and want a matching clutch and brake, Toyota 31321-53010 is a suitable replacement for the stock clutch and brake pedal faces.

Engine Management

As mentioned before, we will be using the stock 2AR-FE ECU. In this case, the tuned ECU from Frankenstein Motorworks, and the accompanying ECU brackets.

Cooling System

Unlike the 2GR-FE, there is no aluminum outlet neck to weld a radiator cap onto, but with the recent release of Wilhelm Racework’s expansion tank, this is no longer an issue. His blog as the installation notes needed. The only difference is he is running a 2GR whereas we are running a 2AR.

The heater return line is highlighted in blue. You will tee into this hose for the expansion tank with a 5/8” hose.

The stock 2AR-FE outlet water neck will not fit in the SW20 chassis as it will cause the hose to crash into the firewall. I used these parts to hook the 2AR-FE into the stock SW20 cooling system.

Water Neck: Dorman 902-5930

Lower/Passenger Hose: GATES 22556

Upper/Drivers Hose: GATES 21760

Heater Return: GATES 19306

Heater Feed: GATES 28469

Note, all of these hoses will need to be trimmed to fit. These images aren't entirely to scale, but they give an idea of what needs to be removed and test fitted.

GATES 21760 (Gold) - Trim about 1-1.5 inches off from the highlighted leg. (Untrimmed in photo)

GATES 22556 (Cyan) - Trim about 1 inch off from the short leg. Trim the longer leg section that includes the sticker. (Untrimmed in photo)

GATES 19306 (Blue) - Trim a bit off the short leg. Trim the long leg off so that the hose is parallel to the shorter leg.

GATES 28469 (N/A) - Trim accordingly (I have removed one of my heater core pipes so I have not used this hose, not pictured).

Dorman 902-5930 (Blue) - Point towards the alternator.

I had to splice a bleed port into the upper/driver-side hose. I built my own however there are off-the-shelf hose joiners with a threaded port. The hose joiner size needed would be 32mm. There’s definitely a better way to do this, but I have not experimented with other hoses yet although I intend to. If I find a better solution for this hose, I will update this guide. It would also be possible to tee this bleeder port into the expansion tank. Omitting a bleed port in this location will airlock the cooling system and prevent flow from exiting the head. I had a horrendous time trying to bleed my cooling system without this port.

If you don't want to use an expansion tank, you can add a radiator cap splice to the upper/driver's side hose and route an overflow hose to the stock MR2 overflow tank. The preferred option is still the expansion tank, as it keeps the system under constant pressure and efficiently removes air. However, the radiator cap splice doubles as a bleed and fill point in one package.

The stock tC hose measures around 1.3in in diameter. A splice close to that size should suffice.

Instead of using the stock 2AR 2-pin coolant temp sensor, you'll need to grab a 3-pin coolant temp sensor. Pins 1 and 2 from the stock connector go to pins 1 and 2 on the replacement connector, and pin 3 goes to the chassis integration connectors and sends a signal to the gauge cluster. This threads into the same place as the stock 2AR coolant sensor at the back of the head. If you are using the Woodsport WASP harness there will be an adapter provided for you.

Toyota 89422-22030 or ACDelco Professional 19322820 work. If you are doing the wiring yourself the connector is 90980-11451.

Intake System

We’re running the Frankenstein Motorworks ECU so we should run the Frankenstein Motorworks MAF pipe. The recommended air filter is the AEM 21-209EDK. With MAF’s 22204-28010 or 22204-0V010. This MAF pipe is paired with the stock 2AR-FE intake elbow. A bracket will need to be fabricated to support the MAF pipe. 

Note, we are doing this swap into an SW20 and not a ZZW30. Order this WITHOUT the bracket.

Exhaust System

Aftermarket

Currently, no aftermarket solutions are entirely bolt-on exhausts for the SW20 and 2AR.

There is the Frankenstein Motorworks header, however, and a simple B-pipe could be made to fit an existing rear muffler section.

OEM

The stock Scion tC2 exhaust manifold and B-pipe fit the SW20 chassis without modification to the exhaust. The front motor mount may need a slight grind in order to clear the exhaust manifold flange. OEM parts are highlighted in gold.

OEM Part Numbers

  • 2011-2013 Scion tC Exhaust Manifold 25051-36010 or 2014-2016 Scion tC Exhaust Manifold 25051-36180

  • 2011-2016 Scion tC Mid-Pipe 17410-36160

  • Exhaust Manifold Gasket 171730V010 or FEL-PRO MS97234

  • OEM Exhaust Manifold to Mid-Pipe Gasket 17451-28040 or FEL-PRO 61106

  • OEM Exhaust Manifold to Mid-Pipe Bolt/Spring DORMAN 675221

Regardless if you go with an OEM setup or aftermarket you will need the O2 sensors

  • Upstream (Manifold) Denso 234-9114

  • Downstream (Mid-pipe) Denso 234-4624

AC System

There are probably many ways to do the AC system with the 2AR, but I think I’ve found a pretty easy solution to it.

Note, like the 2GR, there is no A/C idle up without adding external VSV's or spoofing CAN messages. This leads to a very low idle when the AC compressor is on. There may be a solution to this in the future.

  • AC Compressor: Denso 471-1413

  • AC Bracket: Toyota 12502-0V040

  • AC Bracket Hardware: 4 x Toyota 90105-A0127

  • AC Compressor Hardware: 4 x M8x1.25 70mm

    • Remove the two studs on the AC bracket and use two bolts instead. Leaving the studs in will prevent the removal of the AC compressor when the engine is installed in the chassis.

  • Low-Pressure (Thick) Hose: Four Seasons 55189

  • Low-Pressure Fitting: Cold Hose RB1327

  • High-Pressure (Thin) Hose: Four Seasons 66590

  • High-Pressure Fitting: Cold Hose RB1322

Four Seasons 55189 (Blue), Four Seasons 66590 (Gold)

Hoses

Note, all of these hoses will need to be trimmed and bent to fit. These images aren't entirely to scale, but they give an idea of what needs to be removed and test fitted. Please refer to the measurements below for more accuracy.

Four Seasons 66590 will need about 14.5in from the compressor end into the new chassis side fitting.

Four Seasons 55189 will need about 7in from the compressor end into the new chassis side fitting.

Please test fit and measure your hoses before you cut them to length.

AC Compressor

For the AC compressor, you will need to relocate the stud on the lower port to the lower position.

The accessory belt to use with the swap is just the stock 2AR-FE accessory belt. GATES K060494 for example.

Note about using a tC harness here: the Denso 471-1413 AC compressor uses a different electrical connector than what the 2AR harnesses come with. This is a simple fix. Find the 2 pin connector from the tC, remove pin 2, typically a light green wire, install a new terminal and seal, and insert into pin 3 of the replacement connector. Use plugs to seal the empty positions 1 and 2. Remove pin 1 from the original connector and use heat shrink to seal it off, it will go unused. This goes to BA2 pin 4 on the tC harness, you need to connect it to EA3 pin 16 on the MR2 harness. If you are using the WASP harness, this is already done for you.

Parts shopping list:
Connector: Ballenger CONN-100962 (Toyota 90980-11016)
Terminal: Ballenger CONN-11856 (Sumitomo TS / SL 0.5 - 1.25 mm2)
Seal: Ballenger CONN-00145 (Sumitomo HM / MT / TS wire seal)
Plug: Ballenger CONN-100550 (Sumitomo MT / TS / HX / SL Cavity Plug)

You will have the original 3 pin connector left over from this, you can either zip tie it out of the way or go through the effort of removing all 3 wires from the harness.

Stock 2AR-FE with the FMW tune, FMW header, MAF pipe, catalytic converter and chambered muffler.

Shopping List

Special Thanks

Big thanks to Brayden for letting me host this on his site and for his valuable input in the write-up.

Another huge thanks to the group over in the Frankenstein Motorworks Discord server. Without them, I wouldn’t have considered taking this project on and getting a BAR legal 2AR. Thanks yall!

Max Sehic
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