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Closed vs Semi vs Open Deck Blocks


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  • General Member

Original image form http://www.rslibertyclub.org/forums/showthread.php?94919-Closed-deck-motors!


not much info in one place hope this helps..


How to tell if you have a closed deck EJ20G?
There are 2 ways to tell.

1. Engine code.


[TABLE=width: 100%]


[TD=class: alt2] Closed deck (according to JDM factory parts CD-ROM):

EJ20GDW1HD 1992-05-01 to 1993-08-31 WRX.EJ20G

EJ20GDW1HE 1992-05-01 to 1993-08-31 WRX.EJ20G

EJ20GDW1HJ 1992-05-01 to 1993-08-31 WRXRA.EJ20G

EJ20GDW1HR 1992-05-01 to 1993-08-31 WRXRA.EJ20G

EJ20GDW2HD 1993-05-01 to 1994-09-30 S.WRX.MT.EJ20G

EJ20GDW2HE 1993-05-01 to 1994-09-30 S.WRX.MT.EJ20G

EJ20GDW2HJ 1993-05-01 to 1994-09-30 WRXRA.EJ20G

EJ20GDW2HR 1993-05-01 to 1994-09-30 WRXRA.EJ20G

EJ20GDW4HJ 1993-06-01 to 1995-08-31 WRXRA.EJ20G

EJ20GDW5HJ 1995-09-01 to 1996-08-31 WRXRA.EJ20G (STI VERSION)

Open deck:

EJ20GDX1ND 1993-05-01 to 1994-09-30 AT.EJ20G

EJ20GDX1NE 1993-05-01 to 1994-09-30 AT.EJ20G

EJ20GDW1ND 1993-05-01 to 1994-09-30 W.MT.EJ20G

EJ20GDW1NE 1993-05-01 to 1994-09-30 W.MT.EJ20G

EJ20GDW4HD 1994-06-01 to 1995-08-31 S.WRX.EJ20G

EJ20GDW4HE 1994-06-01 to 1995-08-31 S.WRX.EJ20G

EJ20GDW4ND 1994-06-01 to 1995-08-31 W.WRX.MT.EJ20G

EJ20GDW4NE 1994-06-01 to 1995-08-31 W.WRX.MT.EJ20G

EJ20GDX4NE 1994-06-01 to 1995-08-31 WRX.AT.EJ20G

EJ20GDW5HE 1995-09-01 to 1996-08-31 S.WRX.EJ20G

EJ20GDW5NE 1995-09-01 to 1996-08-31 W.WRX.MT.EJ20G

EJ20GDX5NE 1995-09-01 to 1996-08-31 AT.EJ20G

EJ20GDX5HD 1995-09-01 to 1996-08-31 S.WRX.EJ20G

EJ20GDW5PE 1995-10-01 to 1996-08-31 W.WRX.MT.EJ20G (STI VERSION)

EJ20GDW5PE 1995-10-01 to 1996-08-31 WRXSTI.EJ20G

EJ20GDW5PJ 1995-10-01 to 1996-08-31 WRXRASTI.EJ20G [/TD]



2. Block inspection.

If you have a closed deck block, there will be a 'cross hatching' pattern on the block right by the alternator bracket and cam angle sensor.




Open Right Closed Left NOTE "steps" on the Starter housing via the casting process

http://www.i-club.com/forums/showthread.php?t=69788&highlight=open+deck+closed+engines]http://www.i-club.com/forums/showthread.php?t=69788&highlight=open+deck+closed+engines"]Wow this has been answered quite a few times

These engines are aluminum blocks so obviously more metal around the cylinder wall is required unless you wish to put in stell inserts smile.gif

Here's a picture of an open deck (ej20t for example)


Semi Closed ej25t



The fully closed deck


Sleeves being installed (axis monster 2.65l)


[ /quote]

[quote name='"url=http://[url said:

http://www.type-ra.co.uk/vB/showthread.php?p=43533]http://www.type-ra.co.uk/vB/showthread.php?p=43533"] Closed deck block I have been told that you can tell which engine is closed deck by a few simple identification marks stamped on the block. Lines around the starter housing and square patterns inside the bell housing. Along with the same square pattern stamped on top of the block, near where the heads join the block approx under the turbo.


Alot of mixed info in this post I will try & edit later

This might also help:


Look for the extra casting marks as per the picture to identify a fully closed EJ20G block (pre 1997). These came with a Phase I center thrust 48mm crank with piston oil squirters instead of the 52mm BE Bore that phase II cranks now have. The EJ20G can be modified to take either crank giving a better rod selection:


As you can see the ej20 closed-deck block has less holes for the transmission bolts than the EJ207 (because the CDBs goes with 5mt).

I have 6mt so that's the point...wink.gif




Edited by Joker
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  • General Member

I would also imagine they would be better at the apex, as that area could/would be prone to chucking them out over time/abuse

see quick drawing - I might be assuming heaps - might not be physically possible/feasible ( not wanting to thin the walls too much etc)


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  • 4 months later...

So how much does that cost at a machine shop? I was thinking about doing this to the open deck EJ25 found in the 250t. Would make it stand more than a little bit of boost and stop it blowing head gaskets.

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Thers a guy on here and on trademe selling a jason lefting built closed 2.5 for like 1200 bucks i think ..buy that if you want it cause itl be cheaper than getting it done yourself..

To get it done properly is pricey from what iv been told

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  • 2 months later...

IMO the early model closed decks are still the best cause they are the only blocks to incorperate an "oil squiter" behind each piston...

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  • 3 months later...
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