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Old 12-25-2008, 04:43 PM   #1
morrocco88
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Default wrx crank in EJ257 - With 04 wrx heads and sti cams

I've been searchng my butt off about this "de-stroked" setup, but the info seems all over the place. From what I've read the rod ratio is better for less side loading of the piston and can rev a little higher without sacrificing too much bottom end?

I have a complete 04' wrx motor that i will be swapping in and also have an sti shortblock I bought a while back and figured i would make a hybrid before swapping it in, and i have some sti cams I was going to use with a 20G of some sort. This is mainly a street car and want 350wtq with a broad power band and reliabillity.

Do you have to use a custom piston or rod with this setup? What would you end up with if you used a stock replacement sti piston (forged) and the 2.0 cank with the stock sti rods, and using the 49cc wrx heads with sti cams? What would the static CR be?

Would this be a good setup for a little revabillity and reliabillity?

I know homemadeWRX knows a little bit on this subject from seeing his post during my searching. A little advice would be cool without getting off topic.
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Old 12-25-2008, 05:30 PM   #2
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i sure someone will chime in with the exact formula, but i HAVE A 103MM SLEEVED BLOCK WITH a STI SPEC C 2.0 Crank. It is the way the puerto ricans get so much power because of the better rod stroke ratio. With 103mm pistions 75mm crank and stock length sti rods, My displacement comes out to 2.5L
2.65l 2.5L
----- ----- = 2.34l
2.50l X
r54
Somewhere in there. Remeber with WRX heads you will need to use .40 cometic gaskets. Also run a line from the extra crank breather to both valve covers.

good luck.
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Old 12-25-2008, 06:56 PM   #3
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yeah, I know just a little on the subject

I know there is someone on the boards running a completely off the shelf setup at 32psi all day long. Reason for that is his setup is a very low compression ratio because of the use of the improperly sized oem parts...ordering a 2mm longer rod will put you in the right ballpark.

I however took that idea and ran a bit further...longer rod, completely redesigned piston, different rings, lighter pin, etc, etc...just to help balance out the weight gain from the rod. I also raised the CR and gave the piston a huge quench pad to all help out.

If you need help with parts or crunching numbers on it, let me know.
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Old 12-26-2008, 01:22 PM   #4
morrocco88
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^^^^ So your saying a 2mm longer rod with stock replacement sti pistons (nothing custom) will get the compression back up a little and get in the ball park?

I know with the sti heads the CR will be way low (I think "Turbo Mike" is running this setup), but what about with the 49cc wrx heads?

Are you offering parts that you designed for your build?
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Old 12-26-2008, 02:27 PM   #5
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this would be a great build, revhappy and nice displacement to make good power, homemade knows a large amount about this, he has so great designs for the destroked 2.5, i think he is running something along those line in his car
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Old 12-26-2008, 03:24 PM   #6
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Quote:
Originally Posted by morrocco88 View Post
Are you offering parts that you designed for your build?
yes, but I can't sell them on here...no vendor yet...still finishing the website

PM and I can tell you more.
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Old 01-05-2009, 10:37 AM   #7
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Quote:
Originally Posted by Homemade WRX View Post
yes, but I can't sell them on here...no vendor yet...still finishing the website

PM and I can tell you more.
what are you revving your motor 2?
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Old 01-05-2009, 11:07 AM   #8
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Quote:
Originally Posted by morrocco88 View Post
^^^^ So your saying a 2mm longer rod with stock replacement sti pistons (nothing custom) will get the compression back up a little and get in the ball park?

I know with the sti heads the CR will be way low (I think "Turbo Mike" is running this setup), but what about with the 49cc wrx heads?

Are you offering parts that you designed for your build?
I would never ever ever ever take a motor apart for any reason and put stock sti pistons back in it... but thats just me. I hope you meant off the shelf forged.

I am running the exact setup you're asking about. 2.0 WRX heads, EJ257 block, destroked with an EJ207 crank.

What would you like to know? I love it..


Quote:
Originally Posted by spoolinsti05 View Post
what are you revving your motor 2?

I shift at 8200 with a GT3582R @ 32 psi.

Last edited by Turbo_Mike; 01-05-2009 at 12:13 PM.
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Old 01-05-2009, 12:36 PM   #9
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Quote:
Originally Posted by spoolinsti05 View Post
what are you revving your motor 2?
my personal motor isn't in an operational car yet...see my build thread

however out of my 3 beta testers, one is still being built down under, the other two are happily spinning to 8500 rpm. Its the cap I had told them as I would rather pop or eat my bearings than have them do it. I hope to realistiaclly have it running before spring time as I finally have a garage to finish my car up in


**Per my lawyers advice and clause, my motor will be the first one to be allowed to advertise any numbers.
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Old 01-05-2009, 05:14 PM   #10
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Quote:
Originally Posted by Turbo_Mike View Post

I shift at 8200 with a GT3582R @ 32 psi.
Subscribed. I am looking at doing almost the exact same thing and have been researching a bunch. Turbo_Mike, do your WRX heads have any modifications to help them rev to 8000+ or are they equipped to handle that in stock form?


So the +2mm rod over stock is what you need to put the piston in the same place, but does this create interference with the WRX heads? Would only certain pistons work?

If so that gives you a higher compression ratio with the WRX heads. Im haven't yet but was going to calculate what that new CR is so I can decide if I want to be more risky with detonation and enjoy better power in lower RPMs. This would most likely hurt the top end but the better rod/stroke ratio could make up for it therefore broadening the powerband even more. Do you guys think this would work or would the CR be too high?

If read a lot about "high quench" pistons really helping prevent detonation, but creating better heat distribution in combustion? I think this could complement a higher CR nicely, and might invest in nice Techworks pistions. Or even wait till HomemadeWRX's new "high quench" design comes out.
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Old 01-05-2009, 08:38 PM   #11
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give me a minute...well still waiting for 'revised' 09 prices for my suppliers...I had 'perfect' time getting my federal tax ID 1 day before the new year
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Old 01-05-2009, 09:45 PM   #12
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To spin 2.0 wrx heads that high, you should be using - upgraded valvetrain, cams, ported heads... Valve job with oversized valves arent a bad idea either...

Quote:
Originally Posted by davis10 View Post
Subscribed. I am looking at doing almost the exact same thing and have been researching a bunch. Turbo_Mike, do your WRX heads have any modifications to help them rev to 8000+ or are they equipped to handle that in stock form?


So the +2mm rod over stock is what you need to put the piston in the same place, but does this create interference with the WRX heads? Would only certain pistons work?

If so that gives you a higher compression ratio with the WRX heads. Im haven't yet but was going to calculate what that new CR is so I can decide if I want to be more risky with detonation and enjoy better power in lower RPMs. This would most likely hurt the top end but the better rod/stroke ratio could make up for it therefore broadening the powerband even more. Do you guys think this would work or would the CR be too high?

If read a lot about "high quench" pistons really helping prevent detonation, but creating better heat distribution in combustion? I think this could complement a higher CR nicely, and might invest in nice Techworks pistions. Or even wait till HomemadeWRX's new "high quench" design comes out.
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Old 01-06-2009, 01:57 AM   #13
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Quote:
Originally Posted by gto7419 View Post
To spin 2.0 wrx heads that high, you should be using - upgraded valvetrain, cams, ported heads... Valve job with oversized valves arent a bad idea either...
You don't have to. They're all the same parts as the EJ207 heads, the ones Subaru say you can rev to 8000rpm.
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Old 01-06-2009, 08:20 AM   #14
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^^^pretty much, well port wise...but not the same as 'big port' 207s

however, I would recommend +1mm valves, springs/retainters and some healthy cams to really take advantage of the high rpm without having to crank up the boost pressure.
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Old 01-06-2009, 11:26 AM   #15
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Quote:
Originally Posted by davis10 View Post
Subscribed. I am looking at doing almost the exact same thing and have been researching a bunch. Turbo_Mike, do your WRX heads have any modifications to help them rev to 8000+ or are they equipped to handle that in stock form?





The heads are 02 WRX castings. They were ported and polished lightly, BC272 cams, BC valve springs, titanium retainers, and decked .020".

The heads can physically handle revving to 8k in stock form, but you wont make any power up there without upgrades.
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Old 01-27-2009, 03:46 PM   #16
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subscribed. This is something that I will be brewing soon.

What do people do for pistons? (besides forged)
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Old 01-27-2009, 04:23 PM   #17
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in for the tech!
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Old 01-27-2009, 06:01 PM   #18
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Hmmm.... I have good 2.0 crank and a sti block just sitting in my attic. Homemade if you need more beta testers let me know, i'd be down for throwing one of these together.

DK
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Old 01-27-2009, 06:14 PM   #19
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ej207 head parts are totally different from ej205. valves, springs, retainers, cams, ports.

you can rev ej207 to 8000-8200 safely but you cant do the same thing in 205 safely.
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Old 01-27-2009, 06:39 PM   #20
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in for the tech!
Ditto.
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Old 01-27-2009, 07:31 PM   #21
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if you want 2.5L's..find an ej257 long block..or do what HMWRX says

he knows everything..for rill.

Last edited by mxpunk; 01-27-2009 at 07:42 PM.
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Old 01-27-2009, 10:07 PM   #22
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ej207 head parts are totally different from ej205. valves, springs, retainers, cams, ports.

you can rev ej207 to 8000-8200 safely but you cant do the same thing in 205 safely.
Subaru part numbers say differently.
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Old 01-28-2009, 08:28 AM   #23
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Quote:
Originally Posted by WrXtaCy2003 View Post
Hmmm.... I have good 2.0 crank and a sti block just sitting in my attic. Homemade if you need more beta testers let me know, i'd be down for throwing one of these together.

DK
shoot me an email if you are serious.
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Old 01-28-2009, 05:54 PM   #24
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Originally Posted by eastcoastbumps View Post
Subaru part numbers say differently.

i am going to give all head related part numbers for ej207 and ej205 thorugh subarufast tomorrow they come differently from the production but when you would like to buy a parts, it gives the same part number for both and it is generally the sti parts. We are sure about all the differences cause we are dealing with ej207 and ej205 for many years.
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Old 01-29-2009, 12:16 AM   #25
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Mine is almost together.
134mm rods
75mm crank
Custom pistons at 9:1 compression ratio
CNC Ported WRX heads
Big cams.

I'll keep everyone updated.

Micah (HomemadeWRX) and I have been planning these builds for some time. We used to be roommates (I slept on his floor for 6months). We used to sit up at night talking, calculating and getting everything figured out. When others were talking about girls and video games, we were talking about cars and engines...
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