Subaru Engine Conversion, Getting lost doing an engine build... Options

[tmcquinn]

My buddy has recommended this board as a potential place to have a mature conversation about a Subaru build. I'd like to know if it's ok with you guys to start a thread here about that? I don't own a 914 but I do have a 987 if that lends me any cred.

Here is the story, as mercifully short as I know how to tell it. I bought a 2003 WRX with the intention of teaching my teenager about engines (which is working) and maybe getting myself back into the game. In retrospect, I didn't know nearly enough to start down this path, though I could say that about a lot of things that ended up being great experiences. Well, it turned out that the prior owner had blown the engine, put in another motor, and blew that one. It had 2 broken rods, broken pistons, and a crankcase that was chock full of chewed up parts. But here is the part that I failed to fully consider: the owner had a 2.5 installed in place of the 2.0 and then just had them bolt the turbo on it. I bought a 2.0 short block from Subaru, some nice heads, oil pump, water pump, timing kit, etc., etc. My goal is a stock 2.0 or close to it. In other words, the exact opposite of nearly every WRX owner on the planet. So now I am in the process of trying to figure out which of the remaining 2.5 parts can't or shouldn't be used when building the 2.0? I will eventually figure this out. But if a conversation like this isn't out of line on this board I would sure like some input from you guys.

[jimkelly]

you asked, so my thoughts, all the best.

I would be almost inclined to welcome this because I am about to do a Porsche 914 suby engine trans conversion, but this is a Porsche 914 forum first and foremost, so probably really not the place. depending on what car your engine is going into, you may want to consider.

http://forums.nasioc.com/
http://legacygt.com/
http://legacycentral.org/

pist: buy a 914 roller and claim you're gonna be a doing conversion like like, and you'd be good to go (IMG:style_emoticons/default/biggrin.gif)

[tmcquinn]

you asked, so my thoughts, all the best.

I would be almost inclined to welcome this because I am about to do a Porsche 914 suby engine trans conversion, but this is a Porsche 914 forum first and foremost, so probably really not the place. depending on what car your engine is going into, you may want to consider.

http://forums.nasioc.com/
http://legacygt.com/
http://legacycentral.org/

pist: buy a 914 roller and claim you're gonna be a doing conversion like like, and you'd be good to go (IMG:style_emoticons/default/biggrin.gif)

No problem. A friend recommended this forum and I figured I'd give it a try.

I like the 914 roller idea but it's hard to make the numbers work once you factor in a divorce...

[matthepcat]

So I am confused, are you trying to get the WRX back together or convert a 914 to a Subaru motor conversion?

[tmcquinn]

So I am confused, are you trying to get the WRX back together or convert a 914 to a Subaru motor conversion?

It's a 100% Subaru build.

I was hesitant to crap up your Porsche forum with my Subaru issues but a buddy told me that this was a great group of guys who did enough Subaru swaps that I might be able to get some help identifying what parts from a 2.5 won't work with a 2.0.

I am participating in other forums but this is a car that really appeals to a younger crowd with a different world view from mine. Returning it to stock is near blasphemy to a lot of WRX owners.

[Mueller]

So I am confused, are you trying to get the WRX back together or convert a 914 to a Subaru motor conversion?

It's a 100% Subaru build.

I was hesitant to crap up your Porsche forum with my Subaru issues but a buddy told me that this was a great group of guys who did enough Subaru swaps that I might be able to get some help identifying what parts from a 2.5 won't work with a 2.0.

I am participating in other forums but this is a car that really appeals to a younger crowd with a different world view from mine. Returning it to stock is near blasphemy to a lot of WRX owners.

Swapping an engine is way different than rebuilding one (IMG:style_emoticons/default/smile.gif)

Since you seem to have all the parts couldn't you just have them sit side by side and see what parts swap onto the known good motor?

1st post has too much info and hard to read. Really don't need or care what broke. I think I read into it as "car currently has a blown 2.5 installed, what parts can I reuse to install a new 2.0 longblock into it?"

[tmcquinn]

Ok, I'm sure you're correct. That was actually the short version!

By the time I got the car it had already been changed to a 2.5. When I bought the 2.0 short block I wasn't even thinking about whether there would be issues with the intake, exhaust, etc. that I was hoping to reuse.

Seriously folks, I realize this is a Porsche forum. We can drop this. I will eventually get it sorted out.

[matthepcat]

Are you able to tell if the 2.5 liter motor was out of an N/A, WRX or STI?

You don't want to use the 2.5l heads on a 2.0.

Most of the accessories are interchangeable, but the injectors are larger on a 2.5l. Do you plan to have the car tuned or trying to run off the stock tune, you need to find out if the ECU is for the motor in the car or the original motor. You also need to find out if it has an aftermarket tune on it.

You can buy a http://www.tactrix.com cable to interface with the ECU and view the logs.

[R_u_dd]

You might want to google on the Franken Motor and the Reverse Franken concepts. You can use use some parts interchangeably depending on whether you want more torque or the turbo. Check my thread under the engine discussion. http://www.914world.com/bbs2/index.php?sho...p;#entry2214816]
Also look at the links in this topic for franken motors. Some of them refer back to the Nasioc Forum. Also look for the links in my thread to favorite subaru conversions. (first page of thread).

Yes, it really is a good group of guys on this forum. I got the chance to meet a lot of them at the West Coast Rumble in Medford, Oregon in May this year.

[tmcquinn]

Are you able to tell if the 2.5 liter motor was out of an N/A, WRX or STI?

You don't want to use the 2.5l heads on a 2.0.

Most of the accessories are interchangeable, but the injectors are larger on a 2.5l. Do you plan to have the car tuned or trying to run off the stock tune, you need to find out if the ECU is for the motor in the car or the original motor. You also need to find out if it has an aftermarket tune on it.

You can buy a http://www.tactrix.com cable to interface with the ECU and view the logs.

I'm pretty sure it was from an N/A. You can see in the paperwork where the shop tried to warn him about just bolting a turbo onto the 2.5. The new heads are installed now but I believe the tops of the turbo pistons have relief cut into them, as opposed to the old engine:

Old Engine

Yes, injectors are one of the things I'm concerned about. Thanks.

The prior owner left me a Cobb A/P in the glove box. I believe I can use it to set the ECU back to stock and create a log file if need be.

[tmcquinn]

You might want to google on the Franken Motor and the Reverse Franken concepts. You can use use some parts interchangeably depending on whether you want more torque or the turbo. Check my thread under the engine discussion. http://www.914world.com/bbs2/index.php?sho...p;#entry2214816]
Also look at the links in this topic for franken motors. Some of them refer back to the Nasioc Forum. Also look for the links in my thread to favorite subaru conversions. (first page of thread).

Yes, it really is a good group of guys on this forum. I got the chance to meet a lot of them at the West Coast Rumble in Medford, Oregon in May this year.

That's one of the best references I've seen all week. Thank you. I have spent many hours on Nasioc and learned a great deal but going 2.5 to 2.0 as well as not wanting more than stock power (for my teenager) make much of what's there not apply.

[matthepcat]

That is why the previous motor blew....wow. The N/A motor is higher compression and different rods & Pistons. The head design is also different.

Nice that the guy included the Cobb. That's like a free $600 and will give you all that is needed to re flash.

What are the smog laws in your area? Only reason I ask, is there is no downside to using that Cobb tuner and running a high flow exhaust for an extra 5-7lbs boost at no effect on longevity. My 06 WRX has been "stage 2" with a Cobb exhaust and tune for 122k miles. (Only annoying thing in CA is swapping out the exhaust every 2 years)

Are you able to tell if the 2.5 liter motor was out of an N/A, WRX or STI?

You don't want to use the 2.5l heads on a 2.0.

Most of the accessories are interchangeable, but the injectors are larger on a 2.5l. Do you plan to have the car tuned or trying to run off the stock tune, you need to find out if the ECU is for the motor in the car or the original motor. You also need to find out if it has an aftermarket tune on it.

You can buy a http://www.tactrix.com cable to interface with the ECU and view the logs.

I'm pretty sure it was from an N/A. You can see in the paperwork where the shop tried to warn him about just bolting a turbo onto the 2.5. The new heads are installed now but I believe the tops of the turbo pistons have relief cut into them, as opposed to the old engine:

Old Engine

Yes, injectors are one of the things I'm concerned about. Thanks.

The prior owner left me a Cobb A/P in the glove box. I believe I can use it to set the ECU back to stock and create a log file if need be.

[tmcquinn]

Yes, that's what we think blew the motor. He overrode what the technicians tried to tell him and then took it and had an aggressive tune put on it. Every piece of paper back to the purchase from the dealer was in the glove box. The story I got was that a 'bad mechanic' caused the disaster but the paperwork and what I saw during disassembly tell a different story.

This car is for my 18 year old. He does not need any extra boost! I am possibly the only guy on the planet trying to build a stock WRX engine. (IMG:style_emoticons/default/smile.gif)