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First build, WRX RA Engine Conversion Log


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First thread so here goes:

So I'm an engineering student bored in the breaks with a workshop at my disposal. I'm driving to work in my N/A Impreza. It's slow, but it carrys everything around, gets up the mountain and survives the occasional off road experience.

So far my practical experience is limited to oil & spark changes and a 20mm sway bar installation on my daily.

After literally months doing my research (like everyone tells you before starting a project like this) I bought this:


Its a wrecked '93 WRX Type RA

Found it on FB, was reasonably priced and had everything I wanted.

The more I was told the better the deal looked from what I could see, aftermarket turbo, V7 Intercooler, ok looking 17x7.5's with good tyres etc.

Look V7 Seats!


So after a trip to Auckland and back at 80km/h, it was on the driveway. I then pulled it to pieces to see exactly what I had bought.

Someone at some point had spent a lot of money on this example, I've found so far:

  • Closed Deck Block from what I can see
  • V7 STi IHI VF30 Turbo, intercooler and intake manifold. V7 STi front and back seats.
  • TiAL EWG on aftermarket Exhaust Manifold of some kind
  • HKS SSQV BOV custom welded on the Intercooler
  • Certed Full Coilovers, random ones up front but Greddy on the back
  • Certed Full Exhaust, up pipe and downpipe (I assume 3" from turbo)
  • 5 Puck Clutch (or so I'm told)
  • 96 WRX Z5 ECU
  • STi 240km/h Cluster
  • Rising Rate FPR
  • RAYS Wheels
  • Under car strengthening braces
  • Freaking silicone vacuum lines everywhere

The car is completely written off, the shock tower is pushed back at an angle from the crash. This isn't going back on the road. ever.

I went to work with the grinder cutting away the mangled metal so I could get to the engine. Found a hole in the rocker cover and a smashed Intake cam pulley. Well good thing that I didn't try to start it haha.

Pulled the cam covers, belt and damaged pulleys and ordered some more from a wrecker in Auckland, all the local ones were shut over new years.


I thought, I'll probably have bent valves from everything being out of time in the crash but I'll give my luck a shot anyway and try start it unopened.

More to come once parts arrive and I can find time to work on it and post.

Edited by mitch8198
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Was going to drop it all in my daily, but I need that, so I went to wellington and bought this the other day instead:


'96 WRX Wagon no motor with Sunroof.

Back to the red car, got the broken cam pulleys off, those things were tight!


Parts arrived, put the cam belt back on, turning engine over by hand hoping to feel 4 compressions.


Can only feel 2 sometimes 3 compressions every couple of crank rotations?? Valves could be bent after all, however compression is good on the side of the crash so it must be the passengers side bank.

Oh well, going to have to cut off the other side of the car so I can get to that rocker cover and see whats going on.

Ideas of the best way forward from here would help heaps, I wanted to attempt to start the engine in the red shell because its still all connected up, but now I probs will have to get the heads off....

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A stone cold low compression engine being turned over by hand and looking for "lumps" isnt really going to tell you much . Itd take 3 full rotations for you to feel compression from each cylinder .

Have you timed up the cam belt properly ?the "marks . Not the arrows . If its got the correct timing then theres no reason not to try start it or do a propper compression test

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Personally it seems that you have plenty of time and space in that cracking looking workshop. Id be tempted to pull to the engine take off everything thats salvageable and bin whats left. Then strip the engine down to the bare components then you can let the dog see the rabbit as it were.

Then that will give you a better understanding of the engine and what you'll need to replace or upgrade...... :):)

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Thanks for the reply's everyone, I am new at this, there's only so much reading can teach you.

AAAAAAAAARRRa: Id love to know a bit more about your car, I'll work out how to PM later with a few Q's.

The interior is still mint and the engine bay looks properly worked. You do nice work man. Sad to have to tear it apart, the rest of the body is soo clean, would have been an awesome car when it was going.

I've now cut away both sides of the chassis back to the engine cross member, I can check under both cam covers now and see whats up.

I used a online service manual to time up the cams, I think its right. The engine was sitting with all the arrows pointing directly down when I opened it up which made me think it was still in time even with smashed up cam gears.

I know deep down a engine rebuild should happen while its out but that is a little out of my comfort zone at the moment, if what lachlan says is correct then all the cylinders may still be ok, I'll have to dig out that compression tester....

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So lachlan was right and crankshaft timing was a little out from the cams, pulled belt for the third time :) and fixed it, compression felt smoother.

put the rocker covers back on, filled the engine with oil and fixed some fried wiring. Fuel pump wouldn't kick in when I turned the key so I jumpered it to stay on with another battery.

Turned the key, only handbrake and oil light came on :confused: but to my surprise the starter kicked in and cranked the engine over. Couldn't get it to run, that might have something to do with the body wiring from the around the front of the car is currently draped across the windscreen :P Also the AFM is broken, the intercooler was off, had no filter and who knows what other parts of the wiring are stuffed from the crash.

Because what's wrong might be caused by the crash is my next step to chuck it all in the silver car with a good loom and try again?

Anyone need any RA bits while I'm pulling the car apart? I don't need the wind up doors etc.

Or has anyone got a engine crane / know a good place I could rent? will need one very soon if this is the way forward.

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Update, got sidetracked getting my 1800cc daily ready for Manfield last Saturday. thought I'd be alright with 70KW until you guys come screaming past at twice the speed on the straights :D

Anyway back on topic, been working couple of hours a night. Took the exhausts off both cars, the downpipe bolts were tight! Swaped over the manual pedal box. Bought a compression tester from supercheap and got 150, 135, 135, 140. Pretty good for a cold engine, not run in months, that used to have a broken cambelt pully and timed by a beginner!

Went and installed a genuine new cambelt kit, the old one was pretty munted. That was expensive :confused:


Today I pulled the whole rear subframe from the silver car, it was auto so the plan was to put the manual diff and rear subframe in there instead so I could be sure I had the right ratios.


Then I pulled the rear subframe from the red car, it had different handbrake assembly inside the hubs?? Then I remembered the RA's had no ABS, so the original hubs had to stay with the car, swapped over the abs hubs and axles to the manual diff, messed around with one seized bolt for ages, it then all splined in great. Split a couple of cv boots in the process, fixing that is a job for another day.

Lifted the manual subframe into the car with a floor jack.

workshop looks like this now, messy and with all the cars on blocks :)


Next step, I borrow the tractor and the engine, box and front subframe go in the silver car.

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Had a guy on the subaru parts page after the wind up cards, could get you the mechanisms if I take those out anyway. I have no idea what the going rate is on these types of bits, I have the same issue on the FB page when people ask for a price haha. how does $20ono each sound? PM and ill send you some closeups

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ok so ran into a problem today while swapping the ecu. the Red RA is a 4 plug Z5 ecu and the silver wrx recipient only has a 3 plug ECU connector with a random white one off to the side, no idea what it does. It has GF8D on the plate (V4?) but still lists EJ20G as the engine. (The shell was auto, I dont think they got the EJ20K)

So all EJ20G were not created equal, I'm regretting not checking the ecu connector when I bought the car. the 3 connectors do plug into 3 out of the 4 connectors on the ecu, i just have to find which wires were on the small yellow plug which doesnt exist in the silver car.

Heres the connector on the donor red car, 4 yellow plugs:


Heres the connector on the recipient silver car, 3 yellow and one random blocked off white on:


Piecing together ECU pin outs for both a 4 plug ECU and a 3 plug EJ20G harness. Looks like I might have to cut the smallest connector off the red harness shift like 12 wires from the other plugs to it and I might be away.

Anyone that has done a 3 plug to 4 plug '20G ecu conversion, help would be much appreciated or if you have wiring diagrams for either that are not in Japanese send me PM

Oh and I pulled the Auto out of the silver car today:


Edited by mitch8198
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Not sure about the cluster, might have been like a factory upgrade or something, 1993 was before the WRX STi was a thing so I guess you could just get "upgrades" from STi division. That really was a pain to swap over.

The fundamental photo, me 1 : subaru 0


Lifted it back into the silver car with just 2 floor jacks and a whole ton of wooden blocks. bolted up no problem :)


Now the wiring, decided ill just multimeter my way through it unless anyone has a '96-98 3 plug '20G diagram. (to go with the ones I found for my 4 plug Z5 and '93 '20G)

Anyone know what that random white plug next to the ecu from the last post is? it still has me stumped

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  • 3 weeks later...

ok so time for a big update, engine is finally fully bolted in and I connected up all the vaccuum lines, heater hoses and throttle cable. Swapped over the boost control solenoid onto the new style mounts.


the wiring, everyones favourite part :P I pieced together wiring diagrams for both the old 20G and the newer 20K. (the silver car has 20K style wiring and 3 plug ecu) I started writing down the differences between the wiring looms in order to plug my 4 plug Z5 ECU in.

I thought that I shouldn't be downgrading the silver car to the unreliable Coil on Plug AND shifting all the wires to fit an older style ECU. I wanted a 3-plug instead, this leaves me with a easy '20K upgrade path. Looked at V4 STi chips (6S etc) but they run the 8:1 CR (not 8.5:1 like the 20G) and have aggressive timing, rev limit and boost maps for my engine. I then found on the internet that SF5 Foresters run the old '20G engine and had late style wiring and wasted spark. I bought a Wasted Spark coil setup from a 250T legacy and matching 4W ECU from a manual forester.

This all fitted on my car well (it already has a V4 manifold) and I adapted the engine loom to '20K style wasted spark using the newer ignitor I found on the car.

Found that my mystery random round plug on the RHS of the engine bay originally had the Cam, Crank and Knock sensors connected to it.

Sensors like these on the red car had such a hack job of wiring them in the past I had to trial and error the pins on the ECU with a multimeter then match up to the '93 pin out, then match up to the untouched loom and pinout on the '20K style wiring. Checked every single wire in the engine loom with a multimeter making sure they all did exactly what I thought they did from the diagrams (didn't want to blow my ECU on the first crack)


Found a battery and turned the key, all dash lights came on, even the CEL so my ECU had booted up. No starter or fuel pump however, must be old AT wiring messing with things. Found an awesome thread on NASOIC about the specific wiring in a manual conversion. Found the reversing lights circuit pins on 9&10 and the ECU Neutral Safety switch on 11&12 of the small AT plug and then wired up accordingly and jumpered the cabin park sensor switch so I could get my key out of the ignition.


Still no pump or starter. Must be the aftermarket immobilizer in the car, never ever used one so I googled about them, didn't know I had to "disarm" it with the fob the owner gave me. Clicked it once and the interior LED stopped strobing at me, fuel pump kicked in and the starter worked (yay) still no spark from the timing light I borrowed.

Plugged the black read connectors in to check, no flashing error code, it should at least have picked up that I don't have a Purple sticker AFM yet. Guess I should reset the ecu first so it can start getting the codes afresh, plugged the green test mode connectors in as well and went through the ECU reset process.

Unplugged the connecters and turned the engine over so the ECU could get a reading and then it randomly fired into life. So stoked :) did it with no intercooler, no AFM and wires spread everywhere. The only error codes were for my missing AFM and the starter circuit being interrupted by the immobilizer.

If you got through all that, well done, this writeup is also for myself so if I have issues I know exactly what I did to the car.

TLDR: Rewired some things, used a Forester ECU, found out how an immobilizer works and got the car started.

Now ill put the car back together when my purple AFM arrives and drive this thing.

Edited by mitch8198
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