Brett_dub
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Posts posted by Brett_dub
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So it looks like they must have changed the size of the chamber on the heads to get a 9.5:1 ratio for the 2012. There are different part numbers for 2010-2011 heads than for the 2012. That’s news to me.
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The 2012 Subaru service manual says our compression ratio is 9.5:1
Just realized you’re probably the guy to ask lol. Seeing as you own an 11’ and 12’
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The 2012 Subaru service manual says our compression ratio is 9.5:1
I’m not sure how reliable the information is, but my Haynes manual makes mention of two different compression ratios. 2010-2011 is listed as 8.4:1 while the 2012 is listed as 9.5:1 . Now that you mention it though, im unaware of any differences between model years of the fifth gen that could cause the change. The pistons appear to be the same part number for all turbo fifth gens. Kind of strange.
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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.
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JE pistons(which series I'm not positive) here with Manley turbo tuff rods. Not any louder than a typical Subaru in my mind.
Guess the answer to your compression question I would not fully know. 8.5:1 or 9.5:1 is where you'd be perhaps
Honestly just stick with another stock shortblock.
Thank you. I calculated the cr for the Manley turbo tuff pistons yesterday and it looks like I’ll be able to keep it at the stock 8.4:1. That’s going with the 17cc dish. I assumed that stock shortblock would be best, seeing as the oil pan would not bolt right up to any aftermarket block for the sti. It should be getting shipped out soon.
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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.
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I did Manley Piston and Rods when I had it rebuilt at 155k
The tuner also mentioned Manley. I’m just overly concerned with piston slap. I have a bad habit of not letting things warm up, but I do think I’ll be more careful with this kind of investment. I’ll order the shortblock and then the Manley pistons based on the bore size.
I’d still like to see what other people have gone with. I’ve read things that mahle is hit or miss, but I would’ve liked to go with 4032s. I almost considered sticking with stock since they’ll be brand new in the shortblock and I haven’t read of many people (fifth gens) having issues with them.
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I would think you would want to do the rods as well, since those are the next most likely failure. Assuming you have taken care of deficiencies in the valve train as well.
I am interested on hearing opinions for pistons as well, although I'm more likely to have a shop build my engine. Maybe...
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From what I’ve read, the stock connecting rods are forged. I’m thinking my best option right now is to buy a new shortblock assembled from Subaru, and swap the pistons out for forged.
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I’m in the process of figuring out what’s going back in the engine during the rebuild. I may buy a shortblock and just pull the stock pistons to replace with Manleys. I’m aware of the different metals and that these are more prone to piston slap. I plan to daily drive the car.
Can anyone vouch for a quiet well made piston they’ve been running?
What compression ratios are you seeing with said piston?
What model was your piston originally intended for?
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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.
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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
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?
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I just got off the phone with the tuner I plan on going with. I was mentioning the block to him and who I should go to for the work, and was pretty surprised to hear his advice. He told me a brand new short block from Subaru is $1000. He said the cost to have the stock one machined would be close to same price and so just buy a new one. Anyone have any prices from the machine work for their blocks?
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Subarupartswarehouse still looks like it’s cheaper than other site, but the websites look identical.
The heads are going to headgames on Saturday as long as my cams get here in time. They’ll check the clearances on the valves as part of the refresh.
I wasn’t aware I could have the injectors cleaned. I’ll definitely have to look into that.
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I went with used 2011 Sti cams and they fit like a glove...
Thanks. I’ll be going with oem as well.
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I think S2baru had to do that, but he has non-OEM STI cams.
That’s what it was. Looks like I’ll be going with oem.
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Thanks for that. I remember reading about someone having a cam machined, but it may have been for a different MY of the Sti.
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This weekend was the first weekend of the engine tear down. I’ve got the heads off and pretty much the only assembled component left is the block. I’ve been putting together a cart on subarupartswarehouse.com for anything that must be replaced regardless of the route I go (hoses, clamps, rusted fuel lines etc). It’s getting expensive:spin:. I’m a little unsure of what route to go moving forward. I’ve spoken with head games motorworks who seem to have an incredible reputation. They quoted me 1200 to refresh the heads and add a spring kit prior to me finding a cracked exhaust valve. Subaru sells the heads for $540 a piece, but I’m thinking those don’t come with springs valves etc. I’d like to go with Sti cams as well, if anyone can chime in on the extra work required for machining the intake cam for the oil scavenger pump.. The block looks fine from what I can see, but I’ll likely be going with new piston rings and bearings just for piece of mind. I’ll post some pictures soon.
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Wow, thanks for that info! That seems like a price I’d have to jump on if it were presented to me. My local Subaru tuner is closed sundays and mondays. I’ll have to stop by there on Wednesday and see what they have to say. Even if I just get an idea of what they’d do could help me decide what route to go.
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It’s hard to say how long it lasted for. I was going uphill over a bridge on my way home from work. As i approached the top of the hill i noticed my temp light flashing red. I looked at the accessport and noticed the coolant temp at 248F. I immediately cut the engine off doing 70 mph and coasted to a stop on the shoulder of the bridge. When I got out, I saw the lower coolant hose hanging from the water pump. It could have fallen off and over heated, or over heated and blown off. Hard to tell. That 248 degree reading is also hard to distinguish since the car wasn’t reading coolant temp if there was no coolant. The engine itself could have been much hotter.
I notice you didn’t mention pistons or bearings. Did you buy a preassembled block? What block did you go with? If it was an STi, did you run into any issue with compatibility of your parts from your legacy?
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Thanks. I intend on speaking with the local Subaru tuner (precision tuning) to get their take on this. I would most likely go to them for the tune after the build is done. They do also build engines.
Forged pistons - What model are you running
in Fifth Generation Legacy (2010 - 2014 )
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