Well. Where there is a will, there is a way. But word of caution. The project that you are trying to accomplish is not an easy task. This is not a simple engine swap, say a 350 motor from a 79 Chevy 1/2 ton truck to an 82 Camaro.
In your case, the 350 will fit, barely. You may have to cut an opening in the firewall to make room for the transmission bellhousing. Speaking on transmission, well. We'll get to that in a minute. Let's finish talking about the motor. You will need to custom fit the subframe to accept the larger motor, obviously. You need to weld brackets for the engine mounts on the subframe. You may have to either raise the hood or cut a hole on the roof. The air cleaner and intake manifold of the 350 will not clear the hood when it is closed. You will also need to get a much larger radiator to compensate the heat the 350 will be generating. That puny stock radiator is not going to cut it.
Now, the transmission. Your Subie transmission will not bolt onto the 350. Even if it could, you'll twist that transmission within minutes from all the torque. So you will need to find either a Turbo 350 or 400, may be a T700 with an overdrive. That transmission is about 18" longer and maybe 6 if not 9" wider that that of the Subie. You may need to cut the floor just a bit to fit. Remember, you already have to cut the firewall for the motor. From the transmission, obviously you'll need a drive shaft. The Subie shaft will be too small and the car came with CV axle. You will need a shortened Chevy drive shaft and mated to a shortened Chevy rear end.
Front axles that came with the Subie will have to be taken out. There is no place to mount the CV shafts into your new transmission. You will also need a solid front end, probably off a Chevy car of the similar year (will have to be shortened, of course). Let's talk the front suspension and steering. You have rack and pinion steering system. Your steering column is attached to the r&p. Your "new" transmission will be in the way of the current rack and pinion steering, I am not even sure as to where to put your steering system.
Then you have to figure out how to attach your steering column (that was on the r&p) on the steering system that you will have to adapt (I don't where that will come from)
I assume that this will be a daily driver, so you will need this vehicle to pass state inspection. So, you will need a running dashboard- speedometer, and all sort. Your engine wiring will have to be adapted to a Chevy end clips. You may call Painless Wiring (that is what they do). They may custom make you one with a Chevy plugs on one end, but a Subaru plugs on the other.
That is all for now, something for you to think about. Personally, I have done engine swap (Nissan 1.6L to 2.0L, Honda 1.5L SOHC to 1.8L DOHC, GM 3.1L to 3.8L Supercharged, and helped a little Dodge 2.5L to 3.5L), but I have never done a Franken-swap. Those swaps were not easy, and consumes a lot of money and time.
Friday, February 6th, 2009 AT 6:21 PM