Swap City: Part 3
Last time on Swap City, we pulled out the stock engine and transmission and readied the engine bay for the WRX motor. To catch up on either of the first two parts, here are the links [Part 1, Part 2]. This weekend, we would be dropping in the WRX engine and transmission, and hooking up the compatible wiring harness. We would also be bolting on various parts to get the engine running.
We started the day by pulling out the stock wiring harness and replacing it with the WRX one. This mess of wires is a headache to look at unless you’ve had a lot of experience dealing with wiring harnesses before — which I most certainly don’t — so it’s a good thing we have someone who does!
Once the wiring harness was in place and partially hooked up, we moved on getting the WRX transmission ready to bolt onto the WRX engine. As you can see below, there’s not much difference in size between the RS and WRX transmissions. The main difference is the gear ratios.
Before we could bolt the transmission onto the engine, the flywheel and clutch had to be put on the engine; we would be transferring the flywheel and clutch from the stock transmission to the WRX one. The flywheel and clutch have a very important relationship when it comes to transferring power from the engine to the wheels. If you are unfamiliar with how these two integral parts work in tandem and care enough to read up on it, go ahead and click here; you’ll be a better car enthusiast for it.
The flywheel we would be installing is a lightweight flywheel, meaning less mass for the engine to rotate, leading to slightly quicker revs and easy rev matching. The flywheel is bolted onto the end of the crankshaft in the engine’s transmission housing.
Next, the pressure plate on the clutch is bolted over the flywheel.
Now that the flywheel and clutch were connected, the transmission can be mounted onto the engine.
One more step was required before we could drop in the WRX engine and transmission into the car — and that was bolting on the engine mounts. And Eddie being Eddie, of course he had aftermarket Group N engine mounts. These engine mounts are made of much stiffer polyurethane, preventing the engine from flexing on start up, shutdown, and hard accelerations — which greatly improves the feel of the drivetrain. Here’s a shot of the mounts in relation to where they sit on the frame and the engine itself.
At last, it was time to drop the WRX engine into its new home!
Since the dimensions of the WRX engine are slightly different than the outgoing RS one, a slight adjustment had to be made. The cruise control cylinder was preventing the engine from being put in place, so we took it out. I never use cruise control anyway, I don’t like the idea of being locked into a speed and I adjust my speed a lot on the freeway.
With the engine and transmission in, we moved onto the problem that was introduced in Part 2 — the mismatching teeth on the steering rack end (from a WRX) and the steering knuckle (from the RS). To remedy this problem, we went to the local junkyard and picked up a WRX steering column with a steering knuckle attached — it also stilll had the steering wheel and boost gauge attached! Score!
However, there was one issue with switching steering columns; the ignition switch key cylinder (where you stick your key into) would have to be removed from the stock steering column and put onto the WRX column we’d be installing because if we didn’t, I would have to use 2 keys to operate the car (one key to unlock the door, and another to turn the car on). This was much harder than just unbolting the ignition switch from one column and putting it on the other — the ignition switch is held on by anti-theft screws, so they’d have to be cut off using a Dremel. Once we got the ignition switch replaced, we installed the WRX steering column and connected it to the steering rack, and now we had functional steering.
Next up was bolting on the various exhaust pipes; all the extra plumbing is a big change from the simple exhaust setup in an NA (naturally aspirated) that I’m used to in the stock RS. Here’s a diagram of the exhaust on a turbocharged Subaru, a good depiction of just how much extra tubing and piping you need for a turbo.
We start with the up pipe and the headers.
The up pipe gets bolted on first, it is attached to the turbo itself.
Then, the headers (exhaust manifold) are bolted onto the bottom of the engine, where it collects the exhaust gases from each cylinder and leads them to the up pipes, which then spools the turbo.
After that, we moved onto the exhaust on the other side of the turbo. Right after the turbo, goes the down pipe.
Following the down pipe, went the mid pipe.
And the final piece of the exhaust is the tail pipe, which of course fit perfectly..wait.
Since these parts were made for the GD chassis of the WRX, the dimensions are different than the GC chassis of this car. This meant we’d have to go to a shop to get the exhaust custom made for the car. But this was a job for another day.
With the WRX engine finally in and almost all the exhaust in, we decided to call it a night.
We just focused on getting the fluids in the car this day. We filled up the transmission and rear differential fluid with some fancy-pants oil straight from Subaru called Extra-S (so JDM!) — which also smelled pretty bad, somewhat like a rancid cooking oil, I’m getting nauseous just writing this.
First, was the transmission, which was the easiest because you can get to it from the engine bay.
The rear differential would be harder to fill up since it’s under the car and there’s no room to pour the fluid in. In order to get the oil in the differential, we would be using a funnel with a long hose connected to it and hold the funnel up high, so we could use gravity to pour the oil in.
Now that the transmission and diff were properly lubricated, the car could technically be safely turned over (started up), but not kept running since we didn’t have a few important things hooked up — more specifically, the intercooler and radiator. So here it goes, our first start up!