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Old 01-21-2015, 12:44 AM   #1
bugeye_drew
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Default Ej20/Ej25 Hybrid build help!!!

Hello Subaru fam, I've now come to a point with my car in which i am strongly considering turning my ej205 into a ej20/ej257 hybrid build. But i have many questions about this build. Should i build my heads ? it currently has 160xxx on it. For the short block i'm planning on buying forge pistons, connecting rods, and bearings but still need help on deciding the brand. Also I am considering building my heads with new valve springs, retainers, and 272 cams. I really just want to achieve 350-400whp. Is this likely with this motor build? Also which brands should i put my trust with in this build?
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Old 01-21-2015, 07:11 AM   #2
fastblueufo
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I build a good bit of hybrids and from experience and a price point this is the best option.
Ej257 case
Sti heat inducted crank
BC rods
JE fsr pistons 99.5mm/25.5cc dish
King bearings
Cosworth 1.1mm thick head gasket
Have head combustion chambers polished.

That will give you around an 8.3 static cr and it will tune out very good.
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Old 01-24-2015, 01:03 PM   #3
cueballsi
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What transmission do you have??? 5 speed? If so, look into the Moore Performance Blast plates as well.


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Old 02-13-2015, 09:16 AM   #4
Fozzsti
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I will concur with fastblue. I used King bearings on my build and they were awesome! They measured exactly what they said they were. Although I bought multiple sets so I could swap bearings around if I didnt like the measurements there was no need. I have had issues with ACL bearings as far as getting a perfect fit and needing multiple sets to make one good set. Kings all I needed was one set. I highly recommend them.

Also the 257 case and heat treated crank are a must. I used Supertech forged/dished pistons for my application and have loved them. Sent them with the block to be bored and installed.

As far as head gaskets I used Cometic but you cant go wrong with cosworth either. And if you dont have the heads matched you will definitely want a thicker head gasket to get your cr under control.

Also I would upgrade to a stage 1 stage 1 plus clutch to help deal with the added power.
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Old 01-13-2020, 05:45 PM   #5
sebastian323
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Hello, I will be building a hybrid EJ20/EJ25 engine.

I have a 2.5L 05 EJ257 STi Block with Wiseco forged pistons, forged rods, stock Sti crank , king racing bearings. My heads are 2.0L AVCS EJ205 .

I will not be doing any modifications to the stock ej20 heads (stamped z20), and will go with a 1.1mm ej25 head gasket.
As I understand the timing belts, and pulleys are the same between the EJ20 and EJ25

Are the head bolts for an EJ20 and EJ25 the same ? IF not which ones should I use?
Can I keep using the stock 10 mm oil pump ?
Is the oil pickup the same ? what about the oil dipstick and tube ?

thank you guys

Last edited by sebastian323; 01-13-2020 at 05:51 PM.
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Old 01-14-2020, 01:02 PM   #6
BlackFighter
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This thread is 5 years old, but lets see if we can help.

I believe the head bolts are the same. Just make sure to upgrade the head bolts to ARP or other aftermarket bolts. DO NOT REUSE OEM BOLTS.

Yes, you can reuse your 10mm oil pump. I would open it up and clean it before reusing. Unless the eng it was on had a spun bearing or something on those lines then it should be ok.

Upgrade to killerB oil pick up. Do not use the OEM pick up, they crack. Not sure about dipstick. Just use the one for the 2.5L

What are your plans for the car? Track it or DD?

Last edited by BlackFighter; 01-15-2020 at 11:45 AM.
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Old 01-14-2020, 01:19 PM   #7
subaru_gc8
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Quote:
Originally Posted by sebastian323 View Post
Hello, I will be building a hybrid EJ20/EJ25 engine.

I have a 2.5L 05 EJ257 STi Block with Wiseco forged pistons, forged rods, stock Sti crank , king racing bearings. My heads are 2.0L AVCS EJ205 .

I will not be doing any modifications to the stock ej20 heads (stamped z20), and will go with a 1.1mm ej25 head gasket.
As I understand the timing belts, and pulleys are the same between the EJ20 and EJ25

Are the head bolts for an EJ20 and EJ25 the same ? IF not which ones should I use?
Can I keep using the stock 10 mm oil pump ?
Is the oil pickup the same ? what about the oil dipstick and tube ?

thank you guys
you should be able to use the stock stuff,. are you using the oil pan from a 257? if so it should be fine. oil pick up has to match what ever oil pan you use
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Old 01-16-2020, 02:57 PM   #8
sebastian323
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Quote:
Originally Posted by BlackFighter View Post
This thread is 5 years old, but lets see if we can help.

I believe the head bolts are the same. Just make sure to upgrade the head bolts to ARP or other aftermarket bolts. DO NOT REUSE OEM BOLTS.

Yes, you can reuse your 10mm oil pump. I would open it up and clean it before reusing. Unless the eng it was on had a spun bearing or something on those lines then it should be ok.

Upgrade to killerB oil pick up. Do not use the OEM pick up, they crack. Not sure about dipstick. Just use the one for the 2.5L

What are your plans for the car? Track it or DD?
I opened up my 10 mm oil pump cleaned it out, and then primed it with assembly lube before closing it up. I also have a 12mm oil pump, but that was on the car when a bearing spun. I also cleaned it but it did have a good amount of scoring on it. I torqued all the bolts on the pump itself to to 35 ftLbs, per a document for the forester I found online. Any idea what the torque specs on oil pump bolts are (not the ones holding it to the block, but the ones on the pump itself)

I bought new EJ20 head bolts. Next time I have to open the engine up, I might upgrade to some of the parts you suggested. I think the killerB pickup should be fairly easy to drop in during an oil change. I am planning on building more of a daily car, and only track it / run it hard occasionally. The car was previously tuned to 350whp by the previous owner before he spun a rod due to not upgrading his internals on the EJ20 engine. I would like to restore this power level, but ~300 HP will be just fine as well


Quote:
Originally Posted by subaru_gc8 View Post
you should be able to use the stock stuff,. are you using the oil pan from a 257? if so it should be fine. oil pick up has to match what ever oil pan you use
I have an Ej257 oil pan with no pickup. I also have an ej205 oil pan with the pickup. I guess I should use the ej205 pan with its corresponding pickup.
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