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Old 12-12-2012, 05:20 AM   #1
Scooby Newbie
Member#: 333602
Join Date: Sep 2012
Chapter/Region: W. Canada
2012 STi

Default Built EJ257 EFR 8374 6xx awhp

Most of the below info is out of date but I want to keep it here to show where my build ideas started. I will see how the engine-turbo-trans combo I am planning for my STi work before doing my 818 build

**Edited the thread title to reflect the status of the build**

So this is the build thread for the engines for both my 2012 sti sedan and my FFR 818.

I plan on pretty much creating the exact same engine for each car. **Perhaps not anymore, we will see **

This is right at the start of my project so there is lots to be done, hopefully by the fall of next year I have at least one engine done and running.

Right now I could use some advice on a few parts others I am already settled on.

The goal is for a daily driver with the ability to put out about 650hp at the wheels. I also want a very very quick revving engine that will do 9500 safely (not that I would spend any time there but head room is a key to this build), so there will be a focus on lightness in components to help achieve that. More than likely that will be reserved for track time (not big into drag racing I prefer autox, rallycross, road course).

Cost; I am fairly well off so this build will be over done enough that 700-750 whp should be no problem, not that I ever will seek that, I'm not greedy. But I am going to spend the money up front to get the best components I can get, no I won't throw money at things but if I have to spend I will, if I spend 15-20k or more per engine well so be it, would rather have it done right the first time and not spend way more in the long run on rebuilding engines because I was cheap initially.

Every day power would probably be in the 400-500 whp range. I am keeping my stock block and turbo for my sti in case something blows up i have an a quick replacement I can drop in. Turbo is a twin scroll .92 BW EFR 8374. I looked at messing around with variable holsets but that will be a project for a track only car with an H6. Also stuck doing this on pump 94 as E85 isn't available where I am. Though I can order bulk 94 and make higher octane with xylene, toluene or something else (I spent a hell of a lot of time in univ working on inorganic and organic chem so I can safely deal with dangerous solvents, reagnets, etc) or just order an unleaded oxengated race fuel.


Block: pinned, o-ringed, darton sleeves, in a 704 shortblock (inspired by junior's build before he sold it)

Crank: Not sure yet, was thinking of a cosworth or arrow (though I think arrow makes the cosworth), will have it nitrided, cryo'd and wpc'd

Bearings: No clue, not sure if mahle's are the best these days but I have seen there is some problems with tolerances with ACL bearings and king bearings are an unknown quantity. I need some definite help here.

Con Rods: 3MI's rods are super sexy, getting them in a 300M 2mm+ light weight version would be right up my alley. Plus Micah knows his ish! I am not discounting doing titanium rods in the quest for lightness (yes I am well well aware of the problems with titanium and the issue of scratches).

Pistons: 8.5 cr JE FSR. Had lots of good experience with JE pistons in other applications and from what I read here they seem pretty awesome. Though if anyone has a suggestion on a lighter but equally robust piston I am all ears or if 3MI releases a piston I will go with that. Also looking at stock piston bore size to start out because more chances for hones later.

Rings: total seal, I just think gapless is the way to go, less blow by is always a good thing.

Wrist pins: either the standard ones that come with a je piston or paeco titanium ones.

Bolts/studs: arp 11mm 625 head studs, and the just arp stuff in general all around.

Gaskets: cosworth head gasket, stock for everything else. may look at hylomar sealant as additional insurance.

Heads/cams/valvetrain: Cosworth heads and cams and valves (+1mm), inconel exhaust, stainless intake, ti retainers, high rpm springs. Possibly ferrea valves not set on cosworth for that, and not set on cosworth for cams but I am just not a fan of what I am hearing about crower, kelford and gsc. Open to suggestions.

Intake manifold: building my own out of carbonfiber composite, I have many years working with CF in sailboats and also in acoustic products. Also have lots of experience in CFD so I think I would rather try this one out on my own. I of course will be sharing what I find and anyone willing to offer advice and help are more than welcome to. I will do a separate thread for my intake manifold.

Headers+exhaust: custom equal length inconel headers and down pipe, ewg (twin tial 38mms should do it), titanium cat back.

Throttle body: skunk2 72mm dbw

Intercooler: spearco custom air-2-water. Lighter, colder, less piping, plus unique, will put a water reservoir in the back.

Cooling: rad, oil and tranny cooler all from mishimoto (and fans).

Crank pulley: ati super damper. taking dampers off I always see as a bad idea. Also will look at some roger clark cam ti cam pulleys (maybe on this one). And cosworth heavy duty timing belt plus cosworth billet timing belt guide.

water/meth: not a big fan of this idea, but I may play around with it.

ECU: motec or syvecs, leaning towards syvecs s8 right now.

Fuel system: blergh, have to sit down and work out the numbers for this. haven't settled on any vendors either. this will be something I deal with later on in the project.

Clutch/flywheel: leaning towards clutch masters fx400 6 puck sprung hub and lightweight alu flywheel. open to suggestions of course, just have lots of experience with CMs gear.

Tubro: The aforementioned borgwarner efr 8374 .92a/r twin scroll with external wastegates

Coatings/treatments: everything I can get coated with the various swaintech coatings I will, also the whole engine will be sent out for wpc treatment. Swaintech stuff is amazing and their coatings really do provide peace of mind, used their stuff before to great success. (the whole outside of the engine is going to be coated with the black body emitter to really bring engine heat down while tracking it.)

Extra's: well tgv deletes will happen, crawford aos, I am going to make sure the rotating components are as finely balanced as possible. will make sure everything is ported as well as it can be. I am really going to focus on proper air and exhaust flow and efficiency. DEI wraps all over the place. etc. etc. etc.

There are lots of other supporting upgrades but they belong in other threads. There will be a full car build thread. This is just a focus on the motor.

I am currently on a wait list for my efr (le sigh) so yeah, early spring I think I will start the actual buying of parts. The wait is so that I can get the list together of exactly what I want/need, lay out the plan, proper funding, cost estimates and quotations/budget and make sure contact with all associated vendors has been made. I do lots of project management so this will be handled as such. The 818 engine will come later after the first is built and verified to that it is everything that I set out, if not then changes will be made for the 818 build.

This will be slow and methodical and any advice and support is of course appreciated. I am well versed with stock subies and built small blocks, and high hp hondas, nissans, Supras, and RX-7's so not my first rodeo though I am new to high power subarus so some questions may be noobish (I've also lurked here for about 4 years, just recently joined though).


Last edited by Matty_STi; 02-01-2013 at 10:52 PM. Reason: edited the thread title to reflect the status of the build
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