TheSamba.com :: View topic - Subaru 2.5l turbo conversion into a 91 syncro

Sat Sep 22, 2012 6:47 pm

I sure miss my Westy ...
So, my new blushing bride and I went out to Vancouver last year and on the way back we came back via the number 3 highway. Well if any of you have traveled along this highway back to Calgary you'll know that it has quite a number of very steep long, long, loooonnnngggg hills. To make a long story short my lovely wife said that unless I make this thing go faster up hills that was the last trip she was going to take.
That my friends, was the beginning of the adventure.

I knew that I wanted to make this a Subaru conversion so I started looking for a doner car. I came across a guy with an STI who blew his motor and was getting out of it because he was having another kid. I picked up pretty much everything I needed from him ... I thought. Unfortunately there were quite a few small things that I needed to get after the deal was done and I think I still have some odds and ends left to pick up. That all happened last year. I wanted to learn as much as I could about these conversions so I got a bit obsessed with it.
As I was rebuilding the Subaru engine over the past winter I figured out how I wanted things to work and what I needed to get to that point. It's been a lot of fun and I'm currently just working on the front end. Unfortunately, by the time I had got all the parts that I wanted to use, figured out how I wanted it to go together and started the tear down I realized that the entire drivetrain was quite rusted and pretty much everything needed to be replaced end to end.
So I guess this is the story about the conversion that turned into a restoration as well.
The engine is out of a 2007 Subaru STI with a few modifications ... Larger injectors, Manley forged pistons, ported intake, etc. so I think it should be pushing around 350hp at the crank. Hopefully after this my better half should be happy with the uphill pulling power it has. I guess time will tell how this is going to come together but I'm, so far, pretty happy with the results. Still have quite a way to go till I'm finished but it's certainly been a ride so far.

Cheers,
Mike

Sat Sep 22, 2012 6:56 pm

8)

i hope you have a V strong trans to cope with 350 bhp

Sat Sep 22, 2012 7:00 pm

rubbachicken wrote: 8)

i hope you have a V strong trans to cope with 350 bhp

:D Yes! If I were you I'd lower the boost - a lot! If you're easy on the trans it might handle 250 HP.

Let's see some pics of your engine. 8)

Sat Sep 22, 2012 8:00 pm

250? I have a transmission and so does the owner of the old motor in my westy, it ate two transmissions... I was easy on it too.

You need to post pic of this stuff man :)

Sat Sep 22, 2012 8:07 pm

Yup, got Daryl to rebuild the transaxle with all of his goodies and a few that I ordered from Weddel. I tried to get most of the racing stuff I could to give it the best chance possible. Daryl put in his retaining plate as well to keep the bearing from flexing under the power. We ended up tossing all of the magnesium casing parts and replaced them with aluminum. I eventually dug up a used south african aluminum main case from the UK to use in the build. I used the turbo bell housing from Richard in the UK so I could run the stock clutch. From what i understand, most of the strength issues arrive in the transaxle caused by the torque flexing the magnesium main case, twisting and miss-aligning the stuff inside, which as you can imagine, causes premature wear. The aluminum casings should help a lot with that because it's just much stiffer then the magnesium it originally came with. I've heard of people running 250hp through these transaxles without any issues and they are quite hard on them. I'm with you guys on that though and am a bit concerned about the transaxles reliability. I've also been thinking about dropping the boost down to the minimum ~5psi to test everything out. Last thing I want is to drop the transaxle some where.

Sat Sep 22, 2012 9:25 pm

STi's are pretty amazing. My buddie is getting 425 @ the wheels in his, but thats on race gas, torco and spraying meth.

http://forums.nasioc.com/forums/showthread.php?t=2230460

Even at 5psi I think your over 200, I'd put a smaller turbo on that thing (than STi, probably something like a td-04) and enjoy the instant throttle response and transmision longevity. Turbo was on my list but I decided to keep it simple and go w/ n/a 2.5.

Sun Sep 23, 2012 7:00 pm

I was thinking about using the smaller turbo but ended up getting the stock turbo for the engine ... VF43. It's got a pretty quick spool and I'm designing the exhaust to help with that. I'm thinking power should be coming in around 2400 rpm which should be just about right for the gearing. I'm also putting new axles in that spool up a bit to take up some of the stress happening when releasing the clutch. Honestly I'm not all that concerned with anything under 250 hp. More or less, stock transaxles seem to be working well with that amount of power. Well, I guess time will tell. It'll either work or not. If not maybe I'll try to get a Porsche transaxle in there.

Sun Sep 23, 2012 7:56 pm

Tristar Eric put an STI engine in a folks using a Porsche transaxle

Sun Sep 23, 2012 11:36 pm

Along with twisty axles I've found a less agressive clutch does wonders. I'm really fond of kevlar. Stick with a standard HD clutch with a soft, controllable engagement and strong springs to hold the power.

Took me 2 input shafts in my mustang to figure that one out.

Mon Sep 24, 2012 4:27 am

As far as I know Eric used a Porsche G50 2wd transaxle into his beast. I'd love to find someone who has already thrown an AWD version in. I'm not sure how that one would fit. I suspect there would be placement issues and you'd have to do a bunch of cutting and fabricating under there to get it to fit.

Gental clutch, I agree. Not a big fan of the "heavy duty" hybrid clutches some companies are selling. Until they've been around for a while and have proven themselves I won't be using it. Last thing I would want is for a clutch disk to break apart under the strain and make some nasty holes where I don't want them. I'm sticking with the stock subaru STI clutch and flywheel. It can handle the power so it won't fly apart and the springs will suck up some of the engagement energy but won't bottom out too easy. Dumping the clutch is definitely a no no when using this transaxle. Even with my car, I like to walk on it but I don't ever drop the clutch.

Here are some issues I had when I was under the van ...
Rust

Rust

And more rust ...

Mon Sep 24, 2012 6:49 am

There are STI engines in Syncros.
It has been done.

I would focus on the rust before anything mechanical.

The rear crossover that the transmission attachs to should be checked thoroughly.
It will surely be torqued by your choice of powerplant.

Mon Sep 24, 2012 5:58 pm

I actually did. I would more then likely have the conversion all finished now if it wasn't for the rust issues. Fortunately the body and frame portion of the undercarriage really wasn't all that bad. More so all the stuff bolted to it. I ended up tearing everything off and trailering it down to the local DYI sandblasting outfit and cleaned everything up. Finished it off by coating everything with chassis saver. Looks pretty good now and the rust should be held at bay for a while. I even ended up putting some sound barrier under fuel tank before I put it back in with the new SS straps. Before I put a new rad and front end back in I cleaned up the rust spots, sealed it with chassis saver and covered it with that tarry sound barrier. Looks pretty good now. Didn't want to just put the old rust parts back on so I either sandblasted and coated them or replaced them with new.

Here are some before and after pictures.

Mon Sep 24, 2012 6:07 pm

STI's in syncros. Yeah, there are a bunch out there. Mostly the older 2.0l versions but there are more then likely 2.5s as well. Would be great to know what they did with their transaxles. I suspect most kept their originals. Would love to speak with some of them to see how the drive trains are holding out.

Cheers,
Mike

Mon Sep 24, 2012 8:32 pm

purplepeopleeater wrote: 250? I have a transmission and so does the owner of the old motor in my westy, it ate two transmissions... I was easy on it too.

You need to post pic of this stuff man :)

yarp nom nom nom transmissions :lol:

nice looking motor, I like the black breaded lines. will be interesting to hear how it runs. good luck with your progress

Wed Jan 16, 2013 11:17 am

Well it's been a while since I last posted ...
Truly, I am a bit nervous about the transaxle and have done everything possible to make it as strong as it can be, including everything available from the good ol' US of A and going as far as having a used aluminum maincase sent over from the UK. I likely will run very low boost for the first year and have the tranny pulled and checked for wear after that. Realistically I will probably be running closer to 230-250 hp.
Well progress has been a bit slow. I got the clutch in and realized that it was a bit tight so I had to grind a bit off from the bellhousing. Works really slick now. I suppose the issue is that I'm using the stock 240mm pull to release clutch from the STI. All four of the new disk brakes and lines are in, re-did the clutch lines, installed all of the coolant stuff, finished off the fuel lines header has been installed and am working on the rest of the exhaust slowly. Was hoping to get a local welder to build the entire exhaust but the van would not fit into his shop so I have to get it done piece by piece so it's a slow grind. Once the exhaust is done it should go a bit quicker. Bought a powder coating gun so I've been powder coating pretty much everything. It really is a pretty sweet setup and I wish I had picked it up before as I would have done a number if other parts as well.
Here are some more pics ...
Engine and tranny hooked up ...

Engine being lifted ...

Up and getting bolted in ...

Clutch ...

Front g60 calipers before ...

Front G60s after ...

I'll try and get out to the garage this afternoon and send off a couple other pics.

Cheers,
Mike

Wed Jan 16, 2013 12:51 pm

Did you look into the reversed Subaru transmissions? Not sure if they're running in syncros yet, but that would be your best bet in terms of holding the power.

Looks like you've done everything possible to strengthen the syncro transmission though so hopefully it'll hold up if you're carefull.

Looks good, let us know how she runs. Who did your wiring mods?

Wed Jan 16, 2013 1:14 pm

I just heard back from them actually ... Just a few minutes ago. They have a couple prototypes they are working on now and say that the AWD Subaru will fit but its tight. I guess we'll see how that pans out and how my transaxle holds up. After about 6 months of driving I'll bring it back down to Daryl to see how it's holding out. I'll make a decision then if a change is needed. I suspect I will need to change it out by the way everyone is talking here. They are expecting to have a mount made up for the syncro sometime this year so I'm going to be watching that closely.
As for the wiring ... I'm going to be doing that myself. It is definitely intimidating but it shouldn't be that big of a deal. My main concern is the immobilizer ... I'll be just including that portion of the harness to make it work.
If anyone has any advice out there before I start I would greatly appreciate it.
Cheers,
Mike

The wiring rats nest ... My procrastination issue ...

Wed Jan 16, 2013 3:08 pm

I have plenty of experience with the H6s and transmissions.
One of my EG33s is over 300HP....its all how you drive it.
Roast the tires, speed shift and do over 85mph....you will need a few spare trannies for parts and rebuilds for sure.
Short shift, squeeze on the power and stick to 75mph and below.....many, many miles will be possible.

Transmission fluid cooling would be a good investment along with fluid temp monitoring.

Wed Jan 16, 2013 3:12 pm

The previous version RJES bellhousings needs a tiny bit of clearancing for the 240mm flywheel and clutch pack.
The newest run have been updated.
Surely my choice for the sweetest of Subaru conversions. :wink:

Thu Jan 17, 2013 6:50 am

I'm a pretty tame driver when it comes to the van but i guess time will tell. If it doesn't last I'll look into the Subarugears option.
I would also highly recommend RJES for conversion parts as well. Richard has some extremely high quality parts and has the knowledge and experience to back it up. Top notch customer service as well. I wouldn't hesitate at all to get parts from him again.
Hopefully I should get a shwack more done on the van this weekend.
Cheers,
Mike