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Discussion Starter · #1 ·
Engine: 4g63 1990 6 bolt

Are the turbo and non turbo 4g63 heads the same? I.E Size of combustion chamber etc. I tried to search, but found no relevant information. Thanks in advance. Btw, sorry for the newb question lol.
 

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Yea of couse. I was just curious because i wanted to know if the combustion chambers were different and if the cams were different. I would figure the non turbo cams have a little more lift. Also, if the combuston chamber was smaller, id want to use to compression calculator to see where the compression would be.
 

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From my understanding, they are exactly the same except for an insignificant difference in the exhaust cam lift. :p :p
 

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4g63 heads are all the same there only only these differences.

90s have a larger or smaller t stat hosuing?(not sure which again), does not affect anything but they are the same as everything else.

The 6 bolt head and 7 bolt heads use different head studs.

Cams are slightly different but if you have turbo cams throw them in if not dont worry about it. Its not gonna gain you mad JdM hoRse PAwor Yo!!
 

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Red1991TSI said:
It is my understanding that they are. I believe the cam profiles are different. We are speaking 4g63 to 4g63, not 420a.
Yes they are the same. Cams on a N/T are alittle taller on the intake.

USDM 4G63 (Eclipse/Talon Turbo) Stock 248°/248° 200°/200° .349"/.350" 8.86/8.89

USDM 4G63 (Eclipse Non Turbo) Stock 256°/248° 208°/204° .365"/.349" 9.27/8.86


Pulled from Braincrower.com
 

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Engine: 4g63 1990 6 bolt

Are the turbo and non turbo 4g63 heads the same? I.E Size of combustion chamber etc. I tried to search, but found no relevant information. Thanks in advance. Btw, sorry for the newb question lol.
Some NA heads have smaller holes on #1#2 center 2 holes that do not fit over 6 bolt arp head studs without modification .
 
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