How To Do a Subaru WRX Swap into a RS

In this blog post we go over some of the biggest challenges and mistakes people make when swapping a Subaru. A huge shout out to Bucky Lasek for letting us swap his car as well as his dope editing skills! The full weekend swap can be found on the Buck Yeah YouTube channel. Below we've time stamped a few pieces that we think are the most important to make sure your swap goes well. Click here for the Budget and Parts List.

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December 2024 Update: iWire is no longer offering harness merge services so we can focus on other parts of the business, including iDCCD, plug-and-play harnesses, and replacement electrical components. As part of this change, our technical support, wiring guidance, and troubleshooting assistance for harness merge projects will be very limited moving forward.

We appreciate everyone who trusted us with their swap wiring over the years.

These blog posts will remain available as a resource for the Subaru swap community.

To learn more about why we ended our harness merge services, please read the blog post below:

https://iwireusa.com/blogs/iwire-university/why-are-we-ending-our-harness-merge-services

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1. Intro - Do's and Dont's for completing a swap. Watch the first five minutes of this video. You can also check out the iWire Blog for some more Do's and Dont's

2. Buying your engine. Before doing a swap you need to make sure you purchase a good engine. Watch this video to learn more.

Haven't purchased an engine and want some recommendations? Check out our "Easy" Subaru Swaps Blog

Already purchased an engine but not sure which one it is? Watch this Engine Guide Video.

3. Making sure engine is good to go. It's a lot easier to fix connectors, timing belts, hoses, etc. BEFORE the engine goes into the car. Watch this video for some basics of what to check.

4. Removing old engine. Once you've made sure your new engine is good to go and you have the parts ready for the swap, you have to remove the old engine.

5. Old engine pieces onto the new engine. Once you're removed the original engine there are a few pieces you need to take from it to put onto your new engine. These pieces include the alternator and AC compressor. Watch what is needed here:

6. Engine mounting. Once the new engine is prepped an important step is how the engine will actually mount in the chassis. Learn more about cross members, steering racks, steering knuckles, and steering columns here. More detail about crossmember options can be found here

7. Wiring. While you're doing the mechanical changes, you'll also have to make wiring changes so the new ECU talks to the chassis. Here is a post about the general guidelines for this side of the project.

https://iwireusa.com/blogs/iwire-university/options-for-merging-a-wiring-harness-in-your-subaru-swap?_pos=11&_sid=2e7df7b08&_ss=r

We also still carry the harness to we used to perform the merge into the RS

https://iwireusa.com/collections/iwire-plug-and-play-harnesses/products/2-0-wrx-and-2-0-sti-bulkhead-project-harness?variant=44300736004249

You can visit the iWire YouTube for our Harness Removal and Harness Install detailed videos.

8. Priming the engine. We suggest hooking up the minimal pieces needed to do a test fire of the new engine. That way if there are any issues, it's easier to fix and worst case remove the engine.

9. Final pieces. Once the engine is hooked up and good to go it's just about the final pieces like power steering lines, down pipe, O2 sensors, AC compressor and lines, radiator, and putting the interior back together. You'll also want to take the car on a careful test drive to make sure there are no issues.

If this post and our video series don't answer all of your swap questions, we recommend contacting a local shop or if you're going the DIY route utilizing online forums like NASIOC or RS25.

Once you get your engine swap complete iWire has tons of plug and play wiring kits for upgrading your fuel pumps and transmission and wiring kits for tuning like speed density, MAP sensors, and widebands.

iWire Plug and Play Wiring Kits

FPC Hardwire - https://iwireusa.com/products/fuel-pump-controller-hardwire-kit-in-tank-single-pump

Wideband - https://iwireusa.com/products/aem-wideband-x-line-series-with-iwire-pnp

Grounding Kit - https://iwireusa.com/products/grounding-kit

Speed Density - https://iwireusa.com/products/speed-density-wiring-kit

MAP Adapter - https://iwireusa.com/products/map-adapter

AVCS - https://iwireusa.com/products/avcs-bulkhead-kit

iVSS Vehicle Speed Sensor Replicator with Plug and Play Wiring Kit - https://iwireusa.com/products/ivss-vehicle-speed-sensor-replicator-module

Battery Relocation Kit - https://iwireusa.com/products/battery-relocation-kit

Injector Adapters - https://iwireusa.com/products/uscar-injector-adapter

Digital Dash Conversion Harness - https://iwireusa.com/products/haltech-ic-7-digital-dash-adapter-harness

2002-2005 WRX Engine Harness - https://iwireusa.com/products/subaru-2-0l-turbo-intake-manifold-harness-engine-harness