Fifth gen engine rebuild

Brett_dub · April 30, 2020

A new block (10103AC860) is about 1800 depending on your discount. I went that route since really that sort of quality control is hard to beat. Also the fact that i plan on never really going past stage 2 was in play since this is my dad-car. Any real internal
upgrades wont really be used to their potential and be mostly wasted cost

I really can’t believe it’s this cheap but I do have a different part number.

11008AB310

https://estore.subarupartswarehouse.com/p/Subaru_2010_Legacy-25L-TURBO-6MT-4WD-GT-Limited-Sedan/Block-Set-Cylinder-R-DOT/49223192/11008AB310.html

The tuner mentioned that this would be fully assembled, but i think my mind was so blown that I forgot check him on what I believe he said was that it came fully assembled. Pistons, crank etc. Is this true?

Brett_dub · April 30, 2020

Well I guess I rushed to posting before researching. You can buy a short block, or you buy the block. About a thousand dollars difference.

NVAKeith · April 30, 2020

I really can’t believe it’s this cheap but I do have a different part number.
11008AB310
https://estore.subarupartswarehouse.com/p/Subaru_2010_Legacy-25L-TURBO-6MT-4WD-GT-Limited-Sedan/Block-Set-Cylinder-R-DOT/49223192/11008AB310.html

The tuner mentioned that this would be fully assembled, but i think my mind was so blown that I forgot check him on what I believe he said was that it came fully assembled. Pistons, crank etc. Is this true?

That doesn’t appear to be an assembled short block. Looks like case halves and hardware?

stewdogg · April 30, 2020

Yeah, those are case halves and then you need to put the guts in it.

I had one built from a local builder and that's what they did. They got the case halves and put stage 2 parts in it.

Here'e the build sheet for just my stage 2 block.

(click on the pic to read)

Brett_dub · May 4, 2020

Just placed the order for a new shortblock. I’ll check the stamp on it for bore size and order the Manley pistons once I know a or b block.

The heads got dropped off at headgames motorwerks to get a refresh, spring kit, aftermarket valves, bronze valve guides, and sti cams installed.

First round of parts arrived from Subaru, including the engine seal kit.

Reached out to BNR to discuss sending out the turbo for an 18g build.

s2baru · May 7, 2020

Yes I had a machine shop do that on some GSC stage1 cams. Here's the specs on them

Intake 266 / 225 @ .040" / Peak Lift 10.7MM /

Exhaust 264 / 222 @ .040" / Peak Lift 10.4mm /

After my 20g on and tmic it's a substantial difference in the powerbands being flat to redline. +1valves help a bit too. No real Dyno numbers since it's road time but solid guesses are somewhere around the 370mark.

Brett_dub · May 7, 2020

Yes I had a machine shop do that on some GSC stage1 cams. Here's the specs on them
Intake 266 / 225 @ .040" / Peak Lift 10.7MM /
Exhaust 264 / 222 @ .040" / Peak Lift 10.4mm /

After my 20g on and tmic it's a substantial difference in the powerbands being flat to redline. +1valves help a bit too. No real Dyno numbers since it's road time but solid guesses are somewhere around the 370mark.

370 would be sweet, as long as I could keep the torque under 400. Any idea how those cams compare to stock? I hadn’t done too much of my own research, aside from Fahr-side’s post about powerblock solutions that stated the exhaust flow would be freed up by the extra 1mm of lift. Im Already committed to stock sti cams, but still curious as to the difference.

Brett_dub · May 13, 2020

Bryan at BNR received the turbo on Monday. I had thought I had my mind set on the 18g, but I’m now realizing the turbo would be all tapped out right around 350 whp. Is it true these transmissions can only handle 400 torque?

**cww516** · May 13, 2020

350WHP/350WTQ was the figure I had heard, but that's probably no more reliable than your 400 ft-lb number in terms of actual accuracy, and I think that was without installing blast plates. I do remember something from fahr_side saying that the difference in performance between an 18g and a 20g on a stock engine was that you shift the curves about 500 RPM to the right, and that the peak numbers stay about the same. I think he had said that the STI exhaust cams would help you to take advantage of the bigger turbo, though.

Not sure if you've read through jackal8788's build thread, but there's a lot of good info in there comparing the two, since he ran both. I don't think he ever upgraded the cams, though, so it won't be 100% relevant to your use case. Post 770 or so is the start of a good string of posts comparing dyno results between both turbos, and if you search within the thread for "cam" you'll get a few good discussions about the benefits.

s2baru · May 14, 2020

I notice the mid-range powerband right out the gate once I did the build.

Kinda story line of my car. Stock was 240/242 as a baseline with only axle backs. The standard stage2 items catless dp, full exhaust and racerx tmic on stock fuel system was 297/356. I drove at that power level for nearly 30xxx miles before I popped a piston.

Soooo after a full engine build including some head work, still with stock turbo and fuel we were 335/412. Same Dyno and same tuner. That setup was ran for about 18-20k

Now with a 20g, fmic, 1000cc injectors, dw300 pump. It was retuned on the road rather than a Dyno. But the virtual plots are very flat. Now the numbers are just a guess based on previous owner of the turbo and other 20g gains. Been at this power about 2500miles.

Now my miles might be easier than most. Trips from Boise to Denver, to Seattle and also down to LA and also driven out to Connecticut with it and back. I've done 5-6autoX events and some road course driving skills coaching. Can't say I've had an issue with my trans during almost 50k over 350wtq

Brett_dub · May 16, 2020

That’s the enabling I needed! And just in time!