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Discussion Starter · #1 ·
Hi all,

I bought a bugeye that had a full 04 sti swap. Only thing that wasnt swapped was the ecu and harness so I still have a drive by wire 02 wrx ecu. It was properly tuned by a local tuner who knew the car before I bought it. Long story short ringland failure in cylinder 4. I need a new short block. It has b25 heads which I believe came on the 04/05 sti?

So my question is can I use any year short block or do I need a specific 04 short block? I know other sti have d25 heads so if I want to keep my b25 heads and everything on this blown motor what short block would I need? Can anyone point me in the right direction?

Thanks all!


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As far as I’m aware the short block is compatible across the board.

I wasn’t aware of a single avcs sti, but I don’t know everything.
 

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Discussion Starter · #3 ·
Thanks for the input. Hopefully we'll get some more comments as well.

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Discussion Starter · #4 ·
So I found the exact same ej257 with b25 heads about 2 miles from my house. Motor is out of the car but he is willing to show me a Leakdown test. Will the motor being cold effect the results. I assume so because rings aren't heated and valve may not be seated correctly. Any input? Guys asking $1800 and supposedly the motor has about 3k on it.

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Let's try to break this down, shall we?

Only thing that wasnt swapped was the ecu and harness so I still have a drive by wire 02 wrx ecu.
2002 WRX was not drive-by-wire. Check the throttle body on the engine and ensure that you indeed have a throttle cable. DBW conversion would require ECU, loom, and pedal box from STI.

B25 heads which I believe came on the 04/05 sti?
Yes, this is correct. Are the oil galleys for the AVCS plugged or is the ECU running Carberry and controlling through TGV channel?

So my question is can I use any year short block or do I need a specific 04 short block?
There have been changes to the STI shortblock over the years including different case castings, piston tweaks, and crankshaft heat treating, but they are all interchangeable. The EJ255 shortblock is nearly identical but the pistons have a different dish so care should be taken to establish the correct CR.

So my question is can I use any year short block or do I need a specific 04 short block? I know other sti have d25 heads so if I want to keep my b25 heads and everything on this blown motor what short block would I need? Can anyone point me in the right direction?
No STI has been offered in the USA with D25 heads -- these are exclusive to the EJ255 longblock. The STI has seen three different head configurations since 2004:

B25 for 2004-2006; Intake-only AVCS with sodium-filled exhaust valves
V25B for 2007; Intake-only AVCS, improved coolant passages, loses sodium valves
W25 for 2008-20018 (not RA); Adds AVCS on both intake and exhaust valves

The combustion chamber volume is the same for all heads.

As far as I’m aware the short block is compatible across the board.

I wasn’t aware of a single avcs sti, but I don’t know everything.
DAVCS was introduced in the USDM STi in 2008. 2004-2007 STI had intake-only cam phasing.
 

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Discussion Starter · #6 ·
Your the man. It is in fact running carberry and is drive my wire. I have acvs plugged in on both b25 heads. Tuned for only the front cam position sensor. Block is the ej257.


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Discussion Starter · #7 ·
So someone is selling am ej257 with b25 heads but it's not in the car. Asking $1,800. He said he would do a leak down test for me but the engines going to be cold so will that show false results. Also could I do a compression test with the motor out of the car to make sure the compressions good?

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Your the man. It is in fact running carberry and is drive my wire. I have acvs plugged in on both b25 heads. Tuned for only the front cam position sensor. Block is the ej257.
I suspect there is terminology confusion here. Drive-by-wire is a term that colloquially means a throttle that has no physical connection to the pedal box. What you have is a cable controlled throttle, also called "drive-by-cable."

This makes sense considering you are running a 16 bit ECU on Carberry.
 

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Discussion Starter · #9 ·
Thanks. So I'm going to do a Leakdown on the motor today it's out of the car and cold. What should I be expecting for percentages. I will use 100psi for an easy percentage reading. Since it's cold and supposedly a fairly new block I assume leakage will be higher.

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Thanks. So I'm going to do a Leakdown on the motor today it's out of the car and cold. What should I be expecting for percentages. I will use 100psi for an easy percentage reading. Since it's cold and supposedly a fairly new block I assume leakage will be higher.

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I believe shop manual says anything over 20% indicates a problem.

With my wife's old MS3, two cylinders had a compression of 90 PSI (nominally 150 PSI) and the leakdown was more than 80% loss. Cylinders can have pretty high leakdown loss and still have enough compression to run OK, so don't expect 0%.
 

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Discussion Starter · #11 ·
He claimed 10% Max. We will find out later today :). I will keep all posted. Can't wait to get a new motor in.

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He claimed 10% Max. We will find out later today :). I will keep all posted. Can't wait to get a new motor in.

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10% is pretty good. You'd have almost no loss in compression with that number. Leakdown is undoubtedly a good test, but it only checks the cylinder at TDC. It's always a good idea to couple with a dynamic compression test to be certain. That's going to be hard if the motor is out of the car, but is possible by using a cordless drill to rotate the crankshaft.

DISCLAIMER: Do NOT perform a dynamic compression test with a cordless drill if you have a car with an electric oil pump...
 

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Discussion Starter · #13 ·
Can I compression test with the motor out of the car? I brought my compression tester as well.

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Discussion Starter · #14 ·
So that engine was a bust. Now I'm looking into rebuilding mine with forged internals but I'd like to keep my b25 heads. Any opinions that are reasonably inexpensive $2-5k? I may send it out to be built if anyone knows a good place or I could rebuild the short block myself. I have the 04 sti swap bug eye and a blouch dom3.0xtr with a Garret housing that I will most likely reuse. Motor is out and on a stand now with no plan.

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Discussion Starter · #15 ·
Swap done. I rebuilt the motor. Runs great. Doing the break in. I'm running carberry so my torque obd scanner won't show me the afr. Any suggestions? I don't think my aem gauge is accurate.

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Discussion Starter · #16 ·
For anyone still following this is the cord that runs into the glove box. Must be part of having a computer plugged in for tuning? Anyone have their input? I've driven 250 miles but I'm worried I'm running lean and I'd like to plug in with a phone or laptop to scan the ecu.


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