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compression question
http://www.4g61t.org/forum/viewtopic.php?f=6&t=20904		 Page 1 of 1
Author:  89Mirageman [ Sun Apr 01, 2007 10:34 pm ]
Post subject:  compression question
I am currently building a NA 4G63 with 2g turbo pistons and I need a head for this engine. I am going to the pull apart to get another head and I'm wondering if I get one from a 1.8 Elantra if it'll boost the compression up too much for turbo use? Or should I get a 2.0 DSM head? Can anyone tell me what the C/R will be with the 1.8 head?

This engine is going to be a stock rebuild with a 14b and 450's. I am going to eliminate the balance shafts also. It's basicly going to be a decently quick car that is stock and reliable with ac and all the goodies, not a race car.
Author:  jellyfish420 [ Sun Apr 01, 2007 11:35 pm ]
Post subject: 
i'm not possitive. but i think the heads are the same and the difference is in how tall the block is...i could be wrong though :ANAL:
Author:  89coltgt [ Mon Apr 02, 2007 1:40 am ]
Post subject: 
Chris, I would use a 4g63 head on it since you will already have an 8.5:1 motor with the 2g pistons.
Author:  89Mirageman [ Mon Apr 02, 2007 10:13 am ]
Post subject: 
Quote:
Chris, I would use a 4g63 head on it since you will already have an 8.5:1 motor with the 2g pistons.
That's what I was thinking. Turbo and non turbo heads are identical, correct? The cams are the only difference?
Author:  89coltgt [ Mon Apr 02, 2007 10:14 am ]
Post subject: 
Quote:
Quote:
Chris, I would use a 4g63 head on it since you will already have an 8.5:1 motor with the 2g pistons.
That's what I was thinking. Turbo and non turbo heads are identical, correct? The cams are the only difference?
Yessir.
Author:  coltanostra [ Mon Apr 02, 2007 11:31 am ]
Post subject: 
With the 4g67 Head your CR would raise to 9.5:1 which is not the best.Even the Evo3 had Issues with 9.1:1 in stock Trim.
Author:  Flying Eagle [ Mon Apr 02, 2007 12:32 pm ]
Post subject: 
Turbo heads have the hole drilled at the front for the oil pressure to feed the turbo - stock. Not an issue if you can drill tap/or run a turbo that can feed from the oil filter location.
Author:  coltanostra [ Mon Apr 02, 2007 3:30 pm ]
Post subject: 
Quote:
Turbo heads have the hole drilled at the front for the oil pressure to feed the turbo - stock. Not an issue if you can drill tap/or run a turbo that can feed from the oil filter location.
I dont know if there is a difference in EUDM and USDM Parts,but our EUDM NA Heads have the Hole drilled too.
Author:  bfrontin [ Mon Apr 02, 2007 3:54 pm ]
Post subject: 
Quote:
Quote:
Turbo heads have the hole drilled at the front for the oil pressure to feed the turbo - stock. Not an issue if you can drill tap/or run a turbo that can feed from the oil filter location.
I dont know if this is a difference in EUDM and USDM Parts,but our EUDM NA Heads have the Hole drilled too.
confirmed.

im sporting the 4g67 (1.8 ) n/a head (JDM) that comes with the drilled hole standard. there's a lil bolt plug that replaces the turbo banjo bolt.

this is the same on my 4g61 n/a and 4g63 n/a heads i have laying about.

i think all the heads are identical in design/casting. only the port sizes and of course cams/profiles made the difference.
Author:  89Mirageman [ Mon Apr 02, 2007 5:26 pm ]
Post subject: 
Quote:
With the 4g67 Head your CR would raise to 9.5:1 which is not the best.Even the Evo3 had Issues with 9.1:1 in stock Trim.
Thanks! Is this hard to figure out or can you explain how you figured it out? What would the compression on an engine with 1g pistons have with the 4G67 head?
Author:  coltanostra [ Tue Apr 03, 2007 12:42 am ]
Post subject: 
Quote:
Quote:
With the 4g67 Head your CR would raise to 9.5:1 which is not the best.Even the Evo3 had Issues with 9.1:1 in stock Trim.
Thanks! Is this hard to figure out or can you explain how you figured it out? What would the compression on an engine with 1g pistons have with the 4G67 head?
Thats easy.If you swap either a 4g67 on a 4g63,or the other way,a 4g63 on a 4g67 its either exactly +1 CR or -1 CR.
Your CR is 8.5:1 caused by the 2g Pistons +1 by the 4g67 Head.With the 1g Pistons you get 8.8:1
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