Turbo to NA conversion

[Bosco]

I know some of you have done this
We will ignore my reasons for now but I am considering throwing one of a few good NA engines I have into my old Turbo Wagon.
I am hoping some of you can chime in with advice.
I looked but couldn't find much of a thread about the pitfalls of such a task.

This is a 94 turbo wagon, 5mt converted. and I am putting a 93 (probably) NA motor in it.

Here are the potential issues I can predict:

Wiring: I plan to keep the turbo engine wiring harness and maf and just switch the wires for the cam & crank sensors at the ecu.
do I need to switch all the wires or just the + ones?

should I switch out the ecu and maf?

Exhaust: need to switch cross members or fab up some goofy piping.

Radiator: can I get away with rigging up the turbo one?

what else should I be thinking about?
Thanks for any advice.

[vrg3]

You can probably get away with switching just the (+) wires for the cam and crank sensors. I believe the (-) and shield pins go to the same place inside the ECU's case anyway.

The big issue with using the turbo radiator is that there's no radiator cap. The easiest thing, in my opinion, would be to cut the upper hose and splice in one of these: http://www.summitracing.com/parts/MOR-63730/ . I used one on the upper hose of my Legacy for many years. You have to then use one of the larger-sized radiator caps -- one for a 94 Jeep Cherokee 4.0L will fit and work right. You'd also need to cap off the little fitting on the upper passenger side of the radiator, but that's easy. You can then remove the cap to burp the system.

[Bosco]

Thanks very much Vikash.
I was hoping you'd chime in.

I am a little confused about the electrics.
I saw in another thread you mentioned that a Hitachi ecu needs Hitachi maf etc and also that the original turbo wiring harness should be used (different plugs near the fuse-box under the hood.)

So, my car was originally a turbo automatic. I did the manual swap (following josh's methods and snipping the AT/MT identification wire) several years ago, and now I've done the NA swap.
so, should I REALLY still be using my original automatic turbo ecu when the car is now Manual and NA?

I actually have the original ECU that came with the 93 NA legacy engine I just installed. I thought it would be good to have the correct ecu to match the engine/injectors I am running, but do the wiring harness differences prevent me from using it?
I was thinking that the swapping of cam/crank sensor wires and the different shaped plugs near the fuse-box would cause problems if I try to run the 93 NA ecu in place of my 94 turbo ecu. Maybe I am just not thoroughly understanding the situation.

AM I making any sense? I'm trying to explain my concerns without rambling too much.

Much thanks for any help from anyone...

[Bosco]

Just a tidbit for anyone in the future that may be trying to do a similar swap:

The coolant crossover pipe that runs beneath the intake can be swapped too.
Using the turbo crossover pipe changes the position of the coolant temp sensors so they can easily be reached by the original turbo wiring harness. otherwise, the wires for those sensors will need to be lengthened.

[Legacy777]

You should run the non-turbo ECU. It is different than the turbo ECU. For the 92-94 models, they all use the black JECS maf, so you'll need to swap that. Other than that, the wiring should all be in place

[vrg3]

Yes, like Josh says, use the 93 NA ECU, use a black-plastic-bodied JECS MAF sensor, and use your car's stock wiring. That means removing the harness from under the intake manifold of the turbo engine and putting it on the non-turbo engine.

And Bosco's right -- the turbo and non-turbo water manifolds are different and put the coolant temperature sensor and sender in a different place, so you'd have to either lengthen the wires (there are three total) or swap the manifolds.

Also -- in 93 the auto and manual non-turbo ECUs were different, so if the donor car was an automatic there's a chance the ECU will give you a little trouble. If that happens, switch to a 93 or 94 manual non-turbo ECU or any 92 non-turbo ECU.

[Legacy777]

From what I've seen from my own experience, the MT & AT ECU's will run the opposite trans just fine. You just have to make sure the AT/MT ident pin is correctly pinned. As I mentioned, I found the 92 non-turbo ECU was pinned backwards from what the manuals stated.

[MConte05]

Well, sounds like everyone has covered what needs to be said.

I use an NA radiator, I hammered the upper radiator frame rail down since the rad sits about a 1/2" lower.... but this is on a rally car, so had no care about it looking pretty.

Used the turbo wiring harness, swapped over the entire intake manifold, but used the NA fuel rails. Swapped the pins for the crank and cam sensor at the ECU side.

Using the NA ECU from a 91 automatic on my 94 leggy manual.

Did switch subframes to an NA version and ran the NA header, was just much easier that way. Subframes are incredibly easy to swap when the engine is out.

Can't really think of any other issues I ran into.... Do you still have the full intake/PCV/crankcase lines from the NA engine? that may pose an issue if you don't.

[Bosco]

Thanks very much guys, this is all very valuable information to me just now.

It's all making sense now, and so far i think I'm doing well.

I've already got the NA motor in the car.
My original turbo wiring harness is installed under the intake.
I did swap in a non-turbo cross-member and NA radiator as well.
I used a vise and some pliers to bend the radiator brackets to fit the slightly lower radiator.

Next, I will need to switch the + cam & crank sensor wires at the ecu connector, Swap in an appropriate ECU & MAF, install non-turbo exhaust, top up fluids and triple check all the clips and hoses are attached and see what happens.

[Bosco]

I should be ready to turn the key on this thing after a couple more hours of tinkering with exhaust pipes and some fluids.

another quick question first:
Am I now free to unplug and remove all the sensors on that black bracket on the passenger strut tower?
The only thing i see in that spot on my other 1st gen legacy (92 fwd auto n/a) is the thingy called the dropping resistor.
I read on here that only automatics were equipped with a dropping resistor (whatever that is) which makes me wonder if I am free to remove that as well since the car has been manual swapped for several years now.

[evolutionmovement]

I'd say try it and see what happens. I'd think you'd be fine. Worst case, it doesn't run right and you reconnect them, I guess. The N/A ECU shouldn't be be paying attention to it either way. I'd just weatherproof the connectors in case you want to use them again.

[vrg3]

Yeah, the NA ECU won't care. Like Steve says, you can unplug them, but do something to protect the connectors so they don't get ruined.

And, yes, the dropping resistor is only for automatics, so you can remove that too.

[Bosco]

Up and running now.
I only drove it for a mile or so and I still have some tidying up to do, but it works!

Thanks very much for the help guys. I really appreciate it.