Hybrid How-To - Engine Removal and Prep Work

Engine Removal And Prep Work
Removing the engine is fairly simple and is best done through the top with a hoist. If you're using the stock transmission, you can leave it in the car. i-Speed does this with a simple transmission support built from a 4x4 piece of lumber, a few angle brackets and an eyebolt. The beam rests on the inner edges of the front fenders and supports the transmission via the pitching rod bracket on the top of the bell housing.

The radiator should also be removed, as the engine must move forward to disengage the clutch from the transmission input shaft before being removed.

Once the engine is out, the crossmember will have to be removed. To do so, you'll first need to unbolt the control arms and steering rack from the crossmember and unbolt the steering shaft from the steering rack. The rack can then drop down and hang from the steering arms.

Mounting The Engine
Installation of the new crossmember is the opposite of removal, with one critical exception. The newer generation GDB chassis has a wider bushing on the front lower control arm, and the control arm slot on the crossmember is correspondingly wider. You must use a carefully selected stack of washers to fill the gap. Just a hint, though. Call them a shim stack, not a washer stack. It makes you sound smarter.

Exhaust
A downpipe and cat for a WRX should fit in any Subaru the engine fits. If you're swapping into an Impreza, in fact, the entire WRX exhaust will fit, with the exception of the front muffler hanger, which you can just leave off. A Forester or Legacy will require a custom or modified Impreza exhaust after the cat.

Cooling System
WRX radiator hoses almost fit. In fact, in most cases, the lower hose can be installed with only minor trimming. The same is true of the upper hose on '99-and-newer cars, while the earlier cars require you to make a new upper radiator hose out of two 90-degree bends and a few inches of pipe.

The WRX's pressure cap is on the engine, so the pressure cap on the radiator needs to be modified to allow coolant to flow from the old cap to the engine-mounted tank. Remember, this hose will be pressurized, so use a reinforced, high-pressure hose.

Miscellaneous
On the off chance your car doesn't have a hood scoop, you better get one. If you already have a hood scoop, you'll need the proper diverter and seal that mate the scoop to the intercooler. The intercooler won't do much good if the air can just blow around it. A WRX diverter will work with some minor trimming and drilling, or you can try to find one for a Japanese hood.

Cars that are '99 and newer have a shorter throttle cable, but creative use of the cruise control cable bracket can make it work-assuming, of course, that you don't want cruise control.

One last detail: You'll also have to find a place to mount the WRX power-steering reservoir.

The Wiring Job
This is a big job. There isn't all that much cutting and splicing, but there is a lot of identifying, unwrapping, and relocating of wires and connectors. We'll cover the basics of what you have to do, but details like wire color or connector shapes may change from year to year. The only way to be sure of what you're doing is to invest in two wiring diagrams, one for the car your donor engine and harness came from, and another for your car.

The third critical branch of the harness runs down the left front fenderwell and enters the engine bay near the battery. The large connector in the middle of the frame is actually the two Very Important Connectors that run to the engine.
The third critical branch of the harness runs down the left front fenderwell and enters th
Doing this means sitting down with the harness and a wiring diagram, and identifying the important parts. Then remove them with hours of tedious tape unwrapping. iSpeed's Adam Levy has done this wiring job countless times. It takes him 15 to 20 hours to do it now, but it took a month the first time. Budget at least a few weeks.
Doing this means sitting down with the harness and a wiring diagram, and identifying the i
Don't be intimidated by this mess. This confusing rat's nest, found under the left front corner of the dash, is just a convenient mounting place for several large connectors. Slide each connector out of the plastic holder and deal with it individually.
Don't be intimidated by this mess. This confusing rat's nest, found under the left front c

When you're done, this should be all that's left. That's the ECU, of course, in the upper right. The gray box to the left is a massive connector called the Super Multiple Junction, or SMJ. The box on the lower right is the fuel pump controller, which is near the fuel pump itself.
When you're done, this should be all that's left. That's the ECU, of course, in the upper
The VIB, or Very Important Branch of the wiring harness can be separated on its own. The gray box is half of the SMJ, or Super Multiple Junction, while the brown and black plugs in the background are the VICs or Very Important Connectors found behind the battery.
The VIB, or Very Important Branch of the wiring harness can be separated on its own. The g
You should have this much harness left to simply throw away. Just a hint, though: Don't throw it away until the car runs.
You should have this much harness left to simply throw away. Just a hint, though: Don't th

You'll need both the WRX fuel pump (just the pump, not the whole assembly shown here) and the fuel pump controller. This section of the harness should have a black/white and black/orange wires going from the controller to the fuel pump, a black ground wire, a black/yellow wire that takes power from the fuel pump relay (wire this to the fuel pump power wire in the new car) and purple/white and green/red wires that go to the ECU.
You'll need both the WRX fuel pump (just the pump, not the whole assembly shown here) and
Most of the harness work happens behind the dash, so start by removing it and the dash bar that supports it. Note that with the dash removed, many of the wires are still attached to the shell. It takes a careful eye to determine the most efficient way to remove the dash.
Most of the harness work happens behind the dash, so start by removing it and the dash bar
The nerve center of the harness is located conveniently behind the heater core (Subaru bastards!) so do your best to drain it, then unbolt it and pull it from the car. Expect it to feel stuck, even with all the bolts removed. The dense tar/dryer lint composite mat lining the firewall will have glued itself to the heater core fittings. Just pull harder.
The nerve center of the harness is located conveniently behind the heater core (Subaru bas