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Old 11-27-2016, 04:21 AM   #1
Scooby Newbie
Member#: 458813
Join Date: Nov 2016
Chapter/Region: RMIC
Location: Colorado
2007 WRX STI
Urban Gray Metallic

Default 07 STI Heads Build/Problems + Dom 1.5XTR + Tune

First post, but I was encouraged to share my build on here for anyone else who may be interested in getting a bit more power out of their car without building the shortblock. I encountered a lot of problems that took time and thought to remedy, so hopefully this can help out anyone who has similar issues! Overall the build came out solidly and I'm happy with it, only 500 miles on build currently and got it tuned yesterday by Harvey at TheBoostCreep on a Dyno Dynamics dynamometer.

Car info: 07 STI, 97xxx miles, protuned on E85.

Mods in the first 90xxx miles done by previous owner:
SPT Intake
Perrin 2.4" inlet
Perrin uppipe
Walbro 255
ID 1000's
Grimmspeed divorced wastegate Downpipe
Perrin 3" midpipe and axleback
Protune: 20psi on E85, made 320WHP and 360WTQ on stock turbo and mods mentioned above.

Original Issue: Excess coolant in overflow after 90 mile highway drive away from home. In the last mile of the drive back to home, car began overheating. Swapped every part in cooling system, got an upgraded Mishimoto radiator, OEM Thermostat, new thermostat gasket and hoses, and problem was gone...for a couple days. After further diagnosis in the next few weeks, car dumped coolant into overflow after hard runs, determined headgaskets had an internal leak, combustion gases seeping into cooling system through headgaskets, but ONLY UNDER BOOST. Nothing showed up in compression test OR coolant/exhaust gas dye test, no white smoke under boost, only combustion gases into coolant system.

Time for headgaskets! So while the motor was out, I figured I would build the heads and do timing belt. Parts list as follows, but originally I was planning on just doing cams/springs/retainers/head headgaskets and headstuds - all other parts I will list were decided on after pulling parts off and determining they were not in the best shape.

GSC S1 Cams (268/268, 10.8mm of lift)
GSC 60lb springs and titanium retainers
OEM Headgaskets
ARP headstuds
Gates Racing timing kit w/ water pump
Blouch Dom 1.5XT-R w/ 10cm hotside
DEI Turbo Blanket
Tomei UEL Headers/uppipe
JDM TGV deletes
Miscellaneous valve buckets for proper valve lash
IAG Street Air Oil Separator (PCV system leaking oil, decided to upgrade)
ACT Heavy Duty clutch kit (Organic full face disc)
ACT Lightened 15lb Flywheel
TurboSmart 90 elbow hose from turbo to intercooler
NGK Iridium Laser spark plugs
OEM Thermostat (again)
OEM coolant hoses all around
OEM A/C and alternator belts
OEM Master Gasket/Seal set (included Headgaskets and tons of other gaskets/seals)
OEM Hard Turbo feed line at headers (installation problems with Blouch's provided line)
Many 1.3mm copper washers

Company 23 Intake and Exhaust cam gear tools (Crucial to getting gears off)
Company 23 Keeper tool (must get tool centered over valve/spring/retainer, but very helpful and sped up process once we got the hang of it)

Problems and Remedies for those problems encountered with build:
Heads: Cams on driver side (Left) head were hard to spin by hand. Called a machine shop who builds many many Subaru motors and they said putting lapping compound on old cams and spinning in journals for 30 minutes on each side would essentially re-machine that spot. I figured we could try this, or I could buy a new head and cam caps. We lapped both cam journals with the caps off and spent approximately 4 hours with oiled Scotchbrite squares assuring all lapping compound was out of the journals and making sure the journal finish was very fine. To get all lapping compound out of oil passages, we took the heads to a car wash and power sprayed them from every angle and in every hole. Cams spun by hand perfectly after this process. The cams also are specific to left and right head! One pair of cams has a longer nose than the other.

Valve Lifter "Buckets": To get the valve lash within spec, we had to replace 9 of the 16 buckets. GSC's spec given in the box for valve lash on these cams was .010 for intake valves and .012 for exhaust + or - .002. Staying within the tighter side of the specs, we got buckets to make clearances .008" and .010".
Subaru's buckets are measured in millimeters, not inches! We had to do an inches too mm conversion to order the proper buckets.

Carbon Buildup: On 4 of the 8 intake valves, there was a huge excess of carbon buildup. We soaked them in EPR (BG product) and scraped off with a razor blade then used Scotchbrite for the finish. Lots of carbon buildup on pistons, too. We poured more EPR into cylinders and went at it with Scotchbrite, We were VERY careful to NEVER TOUCH the cylinder walls. There was still a fair amount of carbon that was on the cylinder walls now after we had poured out the EPR, so we poured regular oil into the piston walls, let it collect the carbon, and poured it out. This left no carbon in dangerous areas near the cylinder walls and we were able to get all specs of carbon off the pistons using regular motor oil. I will be using much more frequent carbon cleaning additives after seeing the amount of buildup this car had running mostly on E85.

Headers: A common problem I've heard with aftermarket headers; these were very close to the subframe, so close that the distance could probably be measured with feeler gauges. They clanged against the subframe and made an obnoxious noise, so we bent the subframe up where it was hitting. Also, the radiator fans were very close to the headers and required that we trim some of the plastic on one of the fan supports. We heat wrapped where the headers were very close to any plastic as well.

TGV Deletes: For 07 specifically, the two center bolt holes on the intake manifold that bolt into the TGV's needed to be drilled outward to get bolts into JDM TGV Deletes. We used washers on those bolts to spread out the stress on the intake manifold, but they fit well when they were in.

Timing Belt: We tried many, many times to get the timing belt on correctly. We were half a tooth off every time, so eventually we called it good. According to many forums and a retired Subaru master tech, being half a tooth off is completely common and will not hurt anything. The Gates tensioner that came in my kit requires an air bleeding process before installation!

Turbo to Intercooler 90 Elbow Silicone Hose: The turbo changed the length of this connection, so we had to get a longer hose than stock. TurboSmart hose worked perfectly, we could have but did not need to trim the hose to make it fit properly.

Turbo Oil Feed Line at Head: After we were finally able to start the car, the Feed line assembly Blouch provides was absolutely puking oil (about half a quart for 20 second startup). This is another issue on a couple different forums. The problem is that the end of the line slightly offsets the angle that the banjo bolt needs to go in the head. Instead of trying to double up on crush washers and after I was unable to find thicker crush washers, we got a new short factory hard line in that location, which you can screw the turbo line into using Blouch's line adapter bolt they provide with the turbo. This did not leak a drop of oil.

We measured head warpage with a straight edge and feeler gauges. Maximum warpage allowed is .030" according to factory spec. The left head was at .007 in one spot, and the right head was at .015 in one spot, so both were well within spec and we did not machine my heads. Probably not coincidentally, the head with more warpage was the one next to the turbo. We could never get the smallest feeler under the straight edge anywhere on the block surface.

Literally everything was cleaned when it was out and we followed all factory torque specs. We ended up putting close to 70 hours into this build.

The Air Oil Separator installation instructions were on IAG's website and made it fairly straightforward to install.

There is more valvetrain noise than stock, that's something that can be expected with these upgrades. Using the .008" and .010" valve lash that we did, I'm interested to see if there will be more bucket wear and how much mileage I get without problems.

Tune day! Passed smoke test with flying colors, no liquid leaks, clutch break in period was done and cams are essentially ready to go after initial startup break in. Turbo comes with a 15lb wastegate, but the first pull we did, we boosted 19lbs. This made 400WHP on my tuner's dyno, which is just more than safe on the stock shortblock. The reason for overboosting is that the wastegate actuator arm (on the back of the turbo) is getting stuck on the downpipe flange and not allowing the wastegate to open all the way. We did one more pull, final number was 406.4WHP and 390ft lbs of torque on 19lbs of boost on a Dyno Dynamics dynamometer. Harvey (tuner) said this car could definitely make at least 430WHP with a built block on this setup.

I will be grinding down the flange on the downpipe to let the wastegate arm swing all the way, then I'll go back to Harvey to put it on the dyno again. I'll update this thread with the final numbers at 15 or 16psi, and post pictures with this thread when I upload them from my phone. Comment or message me with questions or anything I missed on this or that you may have questions on with your build!
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Last edited by Zaskey; 11-27-2016 at 12:04 PM.
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