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Old 03-22-2006, 11:23 PM   #1
GripGC8
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Default EJ251 block build for FI duty

i happend to pick up a 2001 EJ251 SOHC complete long block today for really really cheap..it has 120k miles on it..its 100% complete...i want to build this motor for FI duties..im new to building subaru motors so i will need some help with this. i have experience building NA and FI honda motors and am currently learning about FI ford V8's as my brother builds his...anyways here we go:

my goals: i want this motor to be able to handle 10-15PSI, 300WHP, it must be reliable, and it will be daily driven.

i currently own a 01 RS, once this motor is built it will go in my RS

heres what im thinking so far:

1. disassemble motor, send block for hot tank, re-honing, re-surfacing of decks.

2. USDM EJ257 crank, con rods, head gaskets, bearings, rings and pistons.

3. all new gaskets and seals throughout block's and heads.

4. aftermarket valve springs, aftermarket cams.

6. resurface stock flywheel, ACT stage 3 clutch

thats all i have as far as long block prep goes...can anyone recommend some valve springs, and cams? ..i want the motor to be making some of the power instead of relying on boost.

as far as the turbo goes im still doing research..below im going to post a list..

please quote this list and fill in the blanks with your recommendations and why you recommend them if im missing anything that you think i might need please go ahead and add it to the list...i will be using this thread as my guide and a place for me to ask questions.

1. TMIC- USDM 04/05 STi?

2. FMIC-

3. Turbo-IHI VF34?

4. Exhaust Manifold-

5. Down Pipe-

6. ECU-

7. Injectors-STi pinks?

8. Fuel Pump-walbro 255?

9. Timing Device-

10. Wideband-

11. BOV-

12. Wastegate-

13. Intake Manifold-

14. FPR-
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Last edited by GripGC8; 03-22-2006 at 11:37 PM.
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Old 03-23-2006, 02:37 AM   #2
ejsportcom
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if you can you should get a set of wrx heads, Im pretty sure they will just bolt up, then you will have dohc.... and 300whp wont be so far out of reach.... or better yet get a set of wrx heads and throw them on a sti short block, it would probably cost the same but then you would have a semi close deck block which is more reliable.

ps- i have some wrx cams if you go that route
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Old 03-23-2006, 09:49 AM   #3
8Complex

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I see no kind of engine management on your list.

Really, if you don't have to deal with emissions, a standalone would work fine, but a swap would be much better ECU-wise.

You shouldn't bother with the EJ251 block, you can get an STI shortblock for less then it'd cost you to build the EJ251. The open deck design of the EJ251 can be a pretty decent downfall, as well.

If you REALLY want to stay SOHC, I believe TWE has head packages, and there are a few companies out there that sells cams for them. If you're willing to go DOHC (the better option, IMO), you have a lot wider selection of cams and other head components.
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Old 03-23-2006, 11:04 AM   #4
Matt Monson
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Quote:
Originally Posted by ejsportcom
if you can you should get a set of wrx heads, Im pretty sure they will just bolt up, then you will have dohc.... and 300whp wont be so far out of reach.... or better yet get a set of wrx heads and throw them on a sti short block, it would probably cost the same but then you would have a semi close deck block which is more reliable.

ps- i have some wrx cams if you go that route
Bzzt! That's a waste of money. The Ej205 WRX heads do NOT flow as well as the SOHC EJ25 heads. And on a boxer, DOHC is not by definition better than SOHC...

Back to the original question: Get a complete set of Ej257 internal from Crawford or one of the other vendors here and rebuild that Ej251 bottom end with fresh bearings and the STi rods and pistons. This will get your compression down to a reasonable level for boosting. Realistically, 300whp is pushing it on that open deck block, but it's been done before. You just need to spend some real money on EM and tune it properly.

But realistically, the above approach will have you around $1000 in parts. For that you can find a good used EJ257 bottom end, or for about 5 hundred more, a new STi block becomes an option...
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Old 03-23-2006, 11:47 AM   #5
ejsportcom
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Quote:
Originally Posted by Matt Monson
Bzzt! That's a waste of money. The Ej205 WRX heads do NOT flow as well as the SOHC EJ25 heads. And on a boxer, DOHC is not by definition better than SOHC...

Back to the original question: Get a complete set of Ej257 internal from Crawford or one of the other vendors here and rebuild that Ej251 bottom end with fresh bearings and the STi rods and pistons. This will get your compression down to a reasonable level for boosting. Realistically, 300whp is pushing it on that open deck block, but it's been done before. You just need to spend some real money on EM and tune it properly.

But realistically, the above approach will have you around $1000 in parts. For that you can find a good used EJ257 bottom end, or for about 5 hundred more, a new STi block becomes an option...
i had no clue the sohc flowed better..... how many cfm are they?
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Old 03-23-2006, 02:46 PM   #6
GripGC8
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wow..i never even considered a EJ257 shortblock instead of building my crappy EJ251.

how much do used EJ257 long blocks go for?(complete block and complete heads)..this way i could just throw it on a stand and build onto it as i collect parts.
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Old 03-23-2006, 03:30 PM   #7
ejsportcom
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Quote:
Originally Posted by GripGC8
wow..i never even considered a EJ257 shortblock instead of building my crappy EJ251.

how much do used EJ257 long blocks go for?(complete block and complete heads)..this way i could just throw it on a stand and build onto it as i collect parts.
new ej257 short blocks go for like $1500 as for the heads i don't really know, thats why i had ssuggested the wrx heads, they can be bought for like $200 used, but if your sohc heads flow better why not just throw those on.....
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Old 03-23-2006, 03:56 PM   #8
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Quote:
Originally Posted by GripGC8
wow..i never even considered a EJ257 shortblock instead of building my crappy EJ251.

how much do used EJ257 long blocks go for?(complete block and complete heads)..this way i could just throw it on a stand and build onto it as i collect parts.
Turbo 2.5 longblocks go for $3K used. The shortblocks, as someone said are around $1600 new, or $1K used. Heads are kinda pricey. Used WRX heads are usually around $500 or so, but you still need the other stuff (IM, wiring, etc). It would be cheaper to buy a WRX longblock for $1-1.5K, the STi block for $1-1.5K and sell the WRX block for $2-400. Either that or just do the EJ205 swap and be done with it.

In either case, I wouldn't bother with the motor you have, but that's just me.
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Old 07-25-2011, 02:17 PM   #9
Suby2.5i
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Even tho its old. For future reference you cant do DOCH heads on our ej251's ecu. The computer isnt ment to read two cam postions and has only one sensor per head.
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Old 12-19-2012, 04:56 PM   #10
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Again information for this old thread. The SOHC heads have a different valve configuration than the EJ257. Therefore the pistons do not match up correctly. You can run it, but it's not ideal. Wiseco does make a SOHC Forged piston, however it is set up for the 5.181" Rods vs. the 5.137-5.141" rods you will find for a EJ257.

My fix for this is going to be custom pistons in the EJ257 shortblock.
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Old 12-22-2012, 03:19 AM   #11
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Best source of info I've found so far : ) Thanks!Merry Christmas
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