2006 Subie STI rebuild

blow-off valve and intercooler

 

BOV is a blow off valve. It relieves boost pressure when you get off the gas.

IC is inter cooler. There are TMIC, top mount intercoolers, which is stock for Subarus and then FMIC or front mount intercooler, which is what my car currently has. Basically a large radiator that helps cool the hot intake air coming from the turbo before it goes into the motor.

 

Well, this is the current situation.





Car had been burning or puking come coolant ever since I bought it. It's recently gotten worse and I've been noticing detonation under higher loads/boost. Talked with my tuner after having the car dynoed to get a baseline of where it's at right now power wise. Still putting down 340whp and 331 wtq. So not bad but it won't live much longer if I don't address the head gasket issue. No oil in water or water in oil at least. So I'm ganking the motor to pull the heads and replace the head gaskets as long as everything looks good otherwise. This is just to see if I can get this motor to last a little while longer to save up funds for a new short block and supporting mods to take it to around 500whp. It already has a FP Red so as long as that's still in good shape, I'll be happy.

On a side note, screw heat wrap. The downpipe has had heat wrap on it since around 2012 I think. This is what I found when I removed the heat wrap. Keep in mind I live in Arizona. Rust doesn't exist here usually. This is an old school HKS catless down pipe.





Yes, it's just surface rust, no it's not bad. But it annoys the shit outta me when you look at the rest of the pipe, lower down on the car. So, it's getting painted with high heat black before going back on. I'll see what I can do for some sort of heat shield, either a blanket or a metal shield. I have no factory brackets for an actual shield tho and I really don't want to have to buy some.

 

What do short blocks cost? That's a bit of work to rip the whole top end off for head gaskets and still be on borrowed time with the old bottom end.

 

Around $3k for an OEM short block, around $5k for a built short block.

It's not bad pulling the motor. 98% of everything that gets disconnected, moved or unbolted is on top of the motor. This also gives me the chance to check the condition of the clutch, clean the engine up and see if there are any other issues. Don't know that it's on borrowed time for the bottom end since that isn't where the problem is. These motors aren't know for randomly spinning bearings or anything else like that when they are properly cared for. The problem is the failing head gasket. It's an OEM gasket, the original from 2006. There have been improvements since then so new headgaskets will likely keep the motor happy until I can replace the short block, which could be in 3 months or 10 months.

 

Finished pulling the engine tonight after work. Finally got a line release tool that worked on the fuel lines. I'll pull the clutch off and get the engine mounted to the stand tomorrow and start inspecting things. I did manage to forget to unplug my oil pressure and temp wires from the sandwich plate when I was ganking the engine and ripped the wires out. Might have killed the O2 sensor in the up-pipe too, forgetting to unplug that, but the wires didn't break. I'll probably replace it regardless, just to CYA.

Stripped the intake off.



Guess the turbo ISN'T a FP Red. Something from Synergy? Haven't taken a closer look at the label yet. Anyone have any ideas?



Slowly lifting.







And out.



Gotta clean that up for sure!

 

2gr swap

 

As I said, get me an adapter plate for the trans and I'll do it.

 

I had an 06 hawkeye stage 2 cobb from 2008 to 2018. Miss that car. Was so much fun

 

damn thats nice af

 

Thanks. It does need some loving, as you can see. Hopefully it doesn't take too long to get back on the road.

 

So some quick googling on the turbo. Looks like Synergy Turbo are no more as a business. The turbo that I have is in good shape at least, with no front to back shaft play. This is what I found on it. Good for up to either 400 or 500 WHP. Not sure on that part yet.

Turbo Model Part Number: TD06HL-20G-8 ST06HL20G8EJ25
Flange: Subaru Triangle
Compressor Diameter: 52.5/68mm
CFM: 640
lbs/min: 44
Turbine AR: 57
Nozzle Area: 8cm
Wheel Diameter: 58.8/67.14mm
Wastegate: 1 Bar
Journal Bearing
Cooling: Oil and water

 

Well, engine is now torn down. Head gasket was failing on the #2 cylinder at the water jacket, just like I thought. This was allowing coolant into the combustion chamber and causing the detonation. The motor never overheated or got hot on me.

Also lots of carbon build up on the pistons from running without an AOS for so long I think. There is corrosion build up where the HG was failing which I think was from running the wrong coolant and/or sitting from 2016 until I bought the car and not getting driven on the regular.

So now I am thinking it would be a waste of time an money to just slap head gaskets on the motor and hope for the best. Not with just over 113k miles on the short block. I'd like to get an Outfront V3 long rod closed deck block but financially, it's most likely going to be a new RA short block.

Here are cylinder 2 and 4. You can see the heavy carbon build up, especially on cylinder 2 (right side in pic) since the fuel was so diluted from coolant. Never blew white smoke tho.



Here's the head, again #2 on the right. You can see the corrosion on the head above #2 which is the intake side. The black mark on the head at the top center is where I think it was leaking into the combustion chamber and causing the coolant to get pressurized and blow out the overflow.



Cam lobes on all 4 cams look excellent, as do all the buckets. Cam journals have some scoring, which is pretty normal from all the cam journals I have seen looking around online. Going to have the heads rebuilt and surfaced.



Cylinders 1 and 3 look about the same as the other side. Still lots of carbon build up.



The head looks much better, no evidence of a failing gasket that I can see but there is corrosion/build up from the coolant.



I've also cleaned up the engine bay and inside of the bellhousing and laid down some fresh paint on the cross member. As well as cleaned up the front end behind the intercooler.

 

Now I know why you've been so busy

 

Slow moving on the rebuild. Engine is completely torn down, heads are dropped off with the tuner to send them to his machine shop for a full rebuild. Shortblock should also be ordered, along with a ton of EOM replacement parts for the engine, headers and some other things that are being replaced/updated. Still a lot to buy too. Meanwhile, I'm cleaning things up and doing some refreshing.

New radiator is on hand now too. CSF. Twice as thick as the stock one and no plastic tanks. Love this thing.



Old engine down to the bare short block. Still has crosshatch in the cylinders, could probably live on for a while but I'm going with a built motor.



Cleaned and painted the intercooler pipes today. Much better in black. Used my favorite bedliner in a spray can for it since it gives a nice texture and is pretty damn tough stuff.

 

Todd. Don’t you have a 4runner to modify?

 

I do. But I can't modify it any further without having another running vehicle. I'm not a hoarder like you and have 6 other cars I can pick from to drive.

 

So, the heads from the old engine are basically junk. Cam journals are too scored to be re-used. Dropping the cams and buckets off tomorrow to make sure those are good and getting new heads ordered from Outfront. Also sending the AVCS cam gears to them for a rebuild.

 

Shiiiiiit, you're going full ham on this bad boy

 

Kinda have no choice for the heads. Even if I went with a cheaper shortblock, I'd still have to get new heads from somewhere. Might as well do it right. Lots of crying with this tho...

Fucker is gunna be fast as fuck tho, boi!