2005 OBXT rebuild

[rrobe99999]

Its finally time for a rebuild after 207K miles. I had P0304 cylinder 4 misfire and found zero compression on cylinder 4 and 60 on cylinder 2. I'm doing a lot of research here and have a few questions to make sure I get it right.

First, I'll cover some history on the car. I bought it from a dealer with 135K miles. I believe it was rebuilt after a turbo failure. I think it has an aftermarket turbo, because it has an adjustable wastegate. It had a new intercooler and the braided turbo oil line with filter. 3 of the 4 banjo bolt screens were removed. I removed the hard one up front. I performed a few mods:

Invidia catted downpipe + custom 3" single exit exhaust

Gutted up pipe with resistor mod

Cobb intake

Cobb AP with OTS stage 2 tune for 93 octane 

Spec Stage2+ clutch and SMFW for 07 LGT, Oversized TOB and forged fork

Timing service 30K miles ago (may reuse pulleys)

I've been very happy with this performance level. My goal is to just fix it back to where it was and get another 200K out of it. I believe the stock engine is fine for these mods. I am getting a new OEM shortblock and having the heads rebuilt. I will replace things as needed during rebuild but will try to reuse all the good parts. Onto the questions:

1.) can I use OEM part number 10103AD020 shortblock without further tuning? Is it identical to my old shortblock?

2.) Do I need to do anything other than what I did during timing service to set the timing?

3.) What seals do I need that are not included in 10105AA720 seal kit?

4.) It seems a few items are mandatory replacements: oil pump, oil pickup, and AVCS solenoids. What else should I replace or upgrade now that I would regret not doing? 

5.) Should I use 1 step colder plugs, NGK LFR7AIX?

Project is going well so far. I have everything disconnected and will pull the engine this weekend when I can get some help. TIA for comments and advice.

 

Edited February 12 by rrobe99999
added to mod list

[kzr750r1]

EJ255 is not using forged pistons. Will it live another 200K without going forged? At stage 2 probably not.

If it's not too hosed up you may be able to get your block rebuilt with new pistons and reuse the rods. Cranks are not that expensive.

Get a shop that knows Subaru for the machine work.

The Company 23 wrenches help.

Correct about #4. Choose your poison, IAG or Killer B for pump and pickup. I went Killer B.

Go for the TIC FU bolts for the cam gears.

Do the #4 cooling mod.

Get the ARP head studs.

Most all the seals will be in the kit you'll need. But take a long look at your hoses. Most will probably be pooched.

Going colder plugs can't hurt. But not really needed.

Get a custom tune.

 

 

[KZJonny]

The 'to go forged or not' debate rages on. 

Given that the part # listed for your shortblock is the Type RA STi, I wouldn't bother swapping out the pistons for forged. Most of the anecdotcal evidence around the Typa RA block suggests that the lightened pistons are stronger from factory and sufficient for a VF52 swap. Hell, plenty of folks have get 200k out of a stock block with a VF52 and a VERY good tune.

If you're going to rebuild your current block, then sure, slap whatever you like in there, but if you're willing to spend a couple extra dollars on the Subaru assembled and tested SB why then pull it all apart for new pistons?

[kzr750r1]

Ahh. I didn't read into it that far. My bad. So we are talking about a EJ257.

[KZJonny]

2 hours ago, kzr750r1 said:

Ahh. I didn't read into it that far. My bad. So we are talking about a EJ257.

Yeah. Specifically the Type RA. So... like 2018+ STi? Until whenever they stopped the EJ25 for good.

I was under the impression that the EJ255/7 were the same anyway except for a tiny difference in piston dish and thus compression ratio. I don't think the metallurgy of the pistons etc... is any different. 

[rrobe99999]

Great information here. I should have been more specific. Want to use the EJ257 RA shortblock, because it seems newer and better but am not sure about compatability with my heads and the COBB OTS tune. I will definitely do the cylinder #4 cooling mod. If I had known about this earlier it may have given me a few more miles on the old engine. I have decided against the ARP studs in case I need to pull heads with motor in car.

[KZJonny]

No compatibility problems at all.

You may want to think about having a proper custom tune done tho. No COBB OTS tune is going to be maximized to an aftermarket turbo.

You want the new build to last a long time, get it tuned for what you install.

[kzr750r1]

 So much faster to pull the motor and rip the heads off than working hunched over the fender.

So much of the motor can be put back together outside of the car it's kinda funny.

You'll get better at it.  I always wondered why there was no talk of adjusting valve gaps. Figured it out we blow them up before needing a rebuild.

Get the head studs, seriously. For a street car there is no need for the big ones... The torque procedure is soooo much better.

Mine are on their second build. No stretch....

Heads are B or D? Either way will work. Just curious.

For real get a custom tune. Just kinda bummed Cobb has gone this green route and we can't delete monitors any more.

Work with a reputable Subaru shop that knows the HW.

My first rebuild made so many mistakes.

Mostly trusting the wrong people.

Have been really happy with this last rebuild.

M45 rebuilt the short block, Wiseco 100mm pistons, new crank and they donated some rods. This is the last bore on this block.

Heads +1 valves, had the new valve guides in hand already from Infamous Performance. Had to buy new castings during the first rebuild, since one shop hosed my original heads. Had him add the valve guides for just in case in the future. So glad I did.

Mike from Infamous hooked me up.

Bummed he had to get out of Cali. But we understand.

 

[rrobe99999]

Thanks for confirming my shortblock selection. Research indicates that I have the B25 heads and I can see they are single AVCS. So the 2009 - 2019 STI RA shortblock is identical to mine with better parts. I will reconsider custom tune and ARP studs. So far, pulling the engine has been easier and faster than my efforts to diagnose the misfire, so that might be the best way to remove a head if needed. I don't have a lot of experience and appreciate all the different POVs

[KZJonny]

Head studs will also hold up better under boost with even a fairly mild tune.

Depending on the specific engine, stock bolts begin to leak arounf 17/18 psi, which is not a lot. I see a little coolant blowby at peak boost of arounf 17.x or so. This is a bummer, and not exactly all that much boost, really.

Head studs are the solution, and are cheap enough.... It would just be annoying to find out that your tune is happy sitting around 18psi, or wants to be (maybe 20psi if that turbo if bigger than stock?), but you really can't use it 'coz you didn't do studs while you had the chance.

Just a thought.

[rrobe99999]

Thanks for the convincing argument. I will use ARP head studs. I pulled engine, manifold and turbo. Turbo looks good, but will probably get a rebuild. It is marked BNR and has 8.06 on the center band. I don't see any other markings. How do I ID this turbo? I lossened cam and crank bolts with timing belt on and flywheel Locked to the engine with a bracket. Would this technique stretch or damage the new belt when I put it back together? Back to work now.

 

On 2/15/2024 at 3:12 PM, KZJonny said:

Head studs will also hold up better under boost with even a fairly mild tune.

Depending on the specific engine, stock bolts begin to leak arounf 17/18 psi, which is not a lot. I see a little coolant blowby at peak boost of arounf 17.x or so. This is a bummer, and not exactly all that much boost, really.

Head studs are the solution, and are cheap enough.... It would just be annoying to find out that your tune is happy sitting around 18psi, or wants to be (maybe 20psi if that turbo if bigger than stock?), but you really can't use it 'coz you didn't do studs while you had the chance.

Just a thought.

Thanks for confirming my shortblock selection. Research indicates that I have the B25 heads and I can see they are single AVCS. So the 2009 - 2019 STI RA shortblock is identical to mine with better parts. I will reconsider

 

 

 

 

[rrobe99999]

Here is the damage. Cylinder 4 ring failed. Oil was getting past it. Cylinder 2 is pretty bad too. The 2-4 head is in bad shape with burnt valves and a cracked one on #2. The other side of the engine doesn't look so bad. What causes one side of the engine to wear out faster? I feel good that I accomplished this thanks to all the information here. Only "oh shit" moment was rounding a cam cap screw. Luckily it was in a good spot to cut the head off with a grinder. Everything came out easily after that. 

[kzr750r1]

Castings are salvageable it seems. But new seats, valves guides and seals with a clea decking they will run for another 200K.

Heat. Funky tune... Get your injectors checked out.

#4 cooling mod should help the next build.

 

[rrobe99999]

My shiny new block is here! It arrived in great shape. It only has 2 small dings on the top front at accessory bolt locations. I can live with that. I'm surprised how light it is. I'm a weak old man and was able to lift it out of the crate. After considering all the mods for this engine I decided to wait until after break in to mess with fuel and emissions. I would probably freak out seeing engine codes thinking I messed something up. I am just doing cylinder 4 cooling mod and throttle body cooling bypass.

[rrobe99999]

Does the new block ship with some oil in it? I finally got it on the stand, put on the crossover pipes and flipped it over. I noticed a tiny bit of oil inside the cylinders that were upside down during the flip and some on the crank. It could have been left in the crossover pipe, but I'm worried that it got past the pistons.

[kzr750r1]

Should have some residual from the initial install of pistons and what not.

What crossover are you talking about? One on the top is coolant.

My guess is the tie to the Oil cooler you're referring to?

Edited March 6 by kzr750r1

[KZJonny]

^ +1

The block would cetainly have been put together with some assembly lube and things like the pistons given a squirt of oil before install.

As long as what you see looks new and clean, I wouldn't sweat it too much. There is really no place that a tiny bit of oil is going to ruin your day. Too much in the cooland won't be great, but you'll have chance to give them a final blast with some brake cleaner and compressed air when completing assembly.....

 

[rrobe99999]

Thanks for the reassurance

[rrobe99999]

I finally got heads back from machine shop and forgot where everything goes on my engine. Where does this bracket go that is shown laying over the up-pipe. It must go on the empty stud, bit IDK 

[KZJonny]

Right there.

I just finished putting all mine back together last weekend and these recent weeknights, so it’s pretty fresh in my mind.

I also kind of know for next time what things have to go in before which other things. Hah!

[rrobe99999]

Thanks. Almost ready to drop it back in

[rrobe99999]

Look like I am missing a part here near the back of the oil pan. It's not on my old block. What is it called?

[Infosecdad]

https://parts.subaru.com/a/Subaru_2005_Legacy-25L-TURBO-5MT-GT-LIMITEDOBKXT-WAGON/_54102_6024591/FLYWHEEL/B13-011-01.html

It's the "Cover Complete Clutch Housing" on that diagram.

[rrobe99999]

Thanks. I ordered one. Sux that I have to wait another week now to finish the job