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Old 04-22-2016, 05:06 PM   #1
Bjwilson1993
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Default Building hybrid for 02 wrx. Questions.

Okay so we're going with a forged short block. (Forged rods and Pistons) http://m.ebay.com/itm/272213507269

Going to port and polish the heads with stage 2 cams https://www.rallysportdirect.com/fit...-272-camshafts

and double spring valve springs.

New headers and up pipe. New Downpipe don't know what turbo to get yet ( please give some suggestions based on build)

Front mount intercooler possibly 555cc injectors. And upgraded fuel pump and obviously a healthy tuning.

Any constructive criticism or ideas are greatly appreciated.
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Old 04-22-2016, 07:23 PM   #2
ripman
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Get the heads chamber matched to the 2.5 bore size.
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Old 04-22-2016, 10:54 PM   #3
danger1138
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Default Building hybrid for 02 wrx. Questions.

What turbo do you plan on running?.. Oops never mind, just read whole thread (aka; point of this thread)..

Id suggest upgrade to at least running 750cc injectors or higher, that way you could atleast support 18g power (i would recommend that sized turbo with your setup,) . That along with the mods you already have waiting to be installed should make for a very fun DD. After the tune obviously.

Last edited by danger1138; 04-22-2016 at 10:59 PM.
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Old 04-23-2016, 02:00 PM   #4
Ryan314
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Quote:
Originally Posted by ripman View Post
Get the heads chamber matched to the 2.5 bore size.
This is the most important aspect of a hybrid build.
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Old 04-23-2016, 10:33 PM   #5
Bjwilson1993
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Will I have to get new fuel rails for the 750cc injectors? Or will stock setup fit?
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Old 04-23-2016, 10:38 PM   #6
Bjwilson1993
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Default Building hybrid for 02 wrx. Questions.

Know any shops in Oregon mid valley area that will chamber match or can I just take the head with a head gasket from the 257 to a machine shop with a CNC machine?
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Old 04-24-2016, 05:12 PM   #7
ripman
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The head gasket is bigger than the bore. I usually pin the gasket on then run a bit of mig wire around inside it and mark it that way.
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Old 04-24-2016, 06:10 PM   #8
04ScoobyWtf
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With my hybrid i didnt chber match at all. I used a cometic 2x thickness hg and that is all.
Specs are 9.0:1 wiseco 100mm pistons, eagle rods, stock crank, arp headstuds, 2x thick cometic hg, stock refreshed heads, 565cc ingectors and vf39. Makes just under 300 at the wheel with crazy off boost torque due to high cr. Due to the high cr i did have to dial down the timing or else i would have made more whp. If i was to do it all over i would simply deburr the heads and run a 8.2:1 piston.

Im also at 25k miles on the build

Last edited by 04ScoobyWtf; 04-24-2016 at 06:32 PM.
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Old 04-24-2016, 07:46 PM   #9
danger1138
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Quote:
Originally Posted by 04ScoobyWtf View Post
With my hybrid i didnt chber match at all. I used a cometic 2x thickness hg and that is all.
Specs are 9.0:1 wiseco 100mm pistons, eagle rods, stock crank, arp headstuds, 2x thick cometic hg, stock refreshed heads, 565cc ingectors and vf39. Makes just under 300 at the wheel with crazy off boost torque due to high cr. Due to the high cr i did have to dial down the timing or else i would have made more whp. If i was to do it all over i would simply deburr the heads and run a 8.2:1 piston.

Im also at 25k miles on the build

I agree with this method. I machined my heads when i went the hybrid route. It has lasted me 90k and counting but ^ this method right here is another route you can take. If you read thru the forums in regards to hybrid builds you will realize that machining your heads isnt the only method for achieving success.
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Old 04-25-2016, 01:29 AM   #10
Bjwilson1993
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Rip this is a big job for a friend so I don't want to really do the machining myself as I am not an experienced machiner. All I've done is port my heads on my 98 DOHC
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Old 04-25-2016, 01:39 AM   #11
Bjwilson1993
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Default Building hybrid for 02 wrx. Questions.

Would the cosmetic 040 HGs work for me? Or are we talking about the ones that are like 1.5thick
http://www.carid.com/cosworth/high-p...FceCfgodnqMBFw
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Old 04-25-2016, 01:38 PM   #12
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Yea theyll work. The thicker you go, the closer to stock cr youll get.
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Old 04-25-2016, 09:17 PM   #13
Ryan314
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Quote:
Originally Posted by danger1138 View Post
I agree with this method. I machined my heads when i went the hybrid route. It has lasted me 90k and counting but ^ this method right here is another route you can take. If you read thru the forums in regards to hybrid builds you will realize that machining your heads isnt the only method for achieving success.
Running a thicker HG is just a band aid fix to not having the heads machined. You will still have head over hang regardless which is prone to hot spots, which can lead to detonation. I'm not saying there hasn't ever been a successful hybrid build without, however, for the cost of having them done, it's a no brainer and shouldn't be overlooked.
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Old 04-25-2016, 10:39 PM   #14
RexWagonWA
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Quote:
Originally Posted by Ryan314 View Post
Running a thicker HG is just a band aid fix to not having the heads machined. You will still have head over hang regardless which is prone to hot spots, which can lead to detonation. I'm not saying there hasn't ever been a successful hybrid build without, however, for the cost of having them done, it's a no brainer and shouldn't be overlooked.
If you do not want to match your 2 ltr. Head to your EJ 257 short block. Buy the JE pistons for the hybrid applications. Have a knowledgable Subaru machine shop work with you. Forget using machine shops that do not have a proven Subaru track record.

GLWYB
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Old 04-25-2016, 11:22 PM   #15
Bjwilson1993
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I found a shop to hand match from the HG just 1mm in from it since the motor is bored to 100
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Old 04-26-2016, 03:12 PM   #16
FlatironsTuning.com
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Quote:
Originally Posted by Bjwilson1993 View Post
Okay so we're going with a forged short block. (Forged rods and Pistons) http://m.ebay.com/itm/272213507269

Going to port and polish the heads with stage 2 cams https://www.rallysportdirect.com/fit...-272-camshafts

and double spring valve springs.

New headers and up pipe. New Downpipe don't know what turbo to get yet ( please give some suggestions based on build)

Front mount intercooler possibly 555cc injectors. And upgraded fuel pump and obviously a healthy tuning.

Any constructive criticism or ideas are greatly appreciated.
With your build, the first thing to consider are your power goals. This will narrow down your turbo selection, and it will help to determine whether some of the other parts are going to be required.

More than likely, you will be happier long term if you go with a larger injector. Specifically a 1000cc injector based on the Bosch EV14 (ID, Cobb, Deatschwerks). Installing them is very straight forward, and won't require rails, etc.

For the cams, and valve springs, again, your power goal, and target RPM redline will help to determine whether you actually need those or not. I'll also say that the dual valve springs may be more complexity than required. you may want to look at a good bee-hive spring in comparison. Remember that typically, the more aggressive the cam, the more you will be sacrificing power in the lower rpm range and gain power in the upper rpm range.

Lastly, you have 3 options to help to compensate for the increased compression and combustion chamber issues of a hybrid. Those are thicker head gaskets, a hybrid piston (JE's as mentioned earlier), and chamber matching the heads. Since you are all ready looking at a built block, you should take a look at the JE pistons. You need forged pistons regardless, and these will take care of both the compression and combustion chamber issues.

I'll mention that the thicker head gaskets are a good option for lower power goals. Also, you want to keep in mind that if your heads have the combustion chamber cracks that the 2.0 heads are prone to, most machine shops will not chamber match them. So that may be an added expense that you want to account for.

I hope that helps, and good luck with your build!
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Old 04-29-2016, 10:02 AM   #17
no694terry
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JE makes FSR pistons specifically for this build that doesnt required heads to be machinced, theyre also dished to pick your compression ration. No more expensive than other forged pistons either.

but if your only going to 555 injectors than your power limit isnt goign to be to the point where this is even an issue
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