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4g67 head vs 4g63 head
http://4g61t.org/forum/viewtopic.php?f=6&t=15736		 Page 1 of 1
Author:  reallyslowcolt [ Sun Nov 06, 2005 12:07 am ]
Post subject:  4g67 head vs 4g63 head
I am currently in the process of building my motor, I was planning on going with 9:1 pistons, but recently discovered that the 4g67 head will fit on the 4g63 block. The 4g67 head is said to have a smaller combustion chamber but raises static compression by approximately 0.4. Also, it seems as though the 4g67 head as larger exhaust ports, according to some other forums, than the 4g63 head. Can anyone verify this to see if it is true? If it is true that the 4g67 head has larger exhaust ports what would be the advantages/disadvantages of going with 8.5:1 pistions and the 4g67 head compared to the 9:1 pistons with the 4g63 head?

Thanks for all your help.
Author:  89coltgt [ Sun Nov 06, 2005 1:56 am ]
Post subject: 
I believe to the best of my knowledge, the in/ex ports are the same size on both heads, it is the combustion chamber size that is different, the 4g67 being a bit smaller. Check out this, should help:
http://www.4g61t.org/phpBB2/viewtopic.p ... 67&t=14041
Author:  dragstr4g61t [ Mon Nov 07, 2005 2:34 pm ]
Post subject: 
Quote:
I believe to the best of my knowledge, the in/ex ports are the same size on both heads, it is the combustion chamber size that is different, the 4g67 being a bit smaller. Check out this, should help:
http://www.4g61t.org/phpBB2/viewtopic.p ... 67&t=14041
completely correct, everything is identical except combustion chamber size...valves are even the same.
Author:  reallyslowcolt [ Wed Nov 09, 2005 2:29 am ]
Post subject: 
thanks guys
Author:  POOKERS [ Thu Nov 10, 2005 12:52 am ]
Post subject: 
so what would that do for hp?
Author:  89coltgt [ Thu Nov 10, 2005 2:50 am ]
Post subject: 
You can use the 1.8l head on a 4g61 and keep the same cc size, but have the bigger intake/exhaust ports like the 4g63 head. You can also use the 4g67 head on a 4g63, and raise you compression ratio, I am not sure how high, though.
Author:  Flying Eagle [ Thu Nov 10, 2005 12:24 pm ]
Post subject: 
Same Cubic Centrimeters measurement in the chamber as the 4g61t head but larger port flow at the top end like a 4g63t setup when mated to the 1G sized parts. When you are done, the only limiting factor other than dialling in boost, is the bore/stroke combination that is different between the two motors. This is assuming all 1G components are bolted to the 4g61t block just as if it were a 4g63t. So, torque will be more limited as a small percentage, and your power map will show the difference between the high end rev characteristics of the 4g61t as compared to the 4g63t with more stroke and bore. 8)
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