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Registered:
December 2004
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Big port vs small port for turbo?
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Fri, 17 December 2004 16:32
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I have an 88 mr2 with a 7 rib big port 4age, I have low compression forged pistions from a 4agze and a forged crank form a 4agze. I'm planning on running a t25 turbo but i need a new head, should I get the big port or small port head and if I get the small port head do I need a new intake manifold?
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Club Member
Location:
sydney
Registered:
May 2002
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Re: Big port vs small port for turbo?
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Fri, 17 December 2004 22:38
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S
E
A
r
c
h
this questions has been done a thousand times
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Location:
Sydney
Registered:
January 2003
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Re: Big port vs small port for turbo?
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Sat, 18 December 2004 04:14
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bigport with TVIS removed is thought of to be better than a smallport when trying to get some reasonably big power.
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I Supported Toymods
Location:
south Melbourne/KL
Registered:
June 2004
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Registered:
December 2004
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Re: Big port vs small port for turbo?
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Sat, 18 December 2004 07:30
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that still doesn't help me with what to do with a turbo set up when I have tthe option of the 7 rib block and any big./small port head. over all I'm looking for 200hp
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I supported Toymods
Location:
sydney.au
Registered:
August 2002
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Re: Big port vs small port for turbo?
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Sat, 18 December 2004 07:35
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88mr2 has the perfect engine setup already
keep bigport head and bigport manifold but lost the tvis (so make up a plate for it)
use 7rib block
use gze pistons and crank
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I Supported Toymods
Location:
south Melbourne/KL
Registered:
June 2004
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Re: Big port vs small port for turbo?
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Sat, 18 December 2004 08:28
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| ae86drift wrote on Sat, 18 December 2004 18:35 |
88mr2 has the perfect engine setup already
keep bigport head and bigport manifold but lost the tvis (so make up a plate for it)
use 7rib block
use gze pistons and crank
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isnt 7 rib block same as gze block apart frm pistons?? 
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Location:
nelson, new zealand
Registered:
October 2004
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Re: Big port vs small port for turbo?
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Sat, 18 December 2004 08:57
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yup the ONLY difference is in the pistons and rings, so i hope you didnt pay too much for that crank! cause your original one is just the same. same with rods etc.
for 200hp i think the small port one would be better, it would have better off boost performance (sumthing to remember if its for a road car) 200hp isnt much for a 4agte. id think a big port head would be better suited to a racer, after more grunt.
well thats my theory anyway.
please note, that doesnt mean i think a big port one would be bad!
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Location:
brisvegas
Registered:
August 2004
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Re: Big port vs small port for turbo?
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Sat, 18 December 2004 23:56
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i think you should use the smallport head, and get it flowed a bit, knife edge the stem between the valves, change the valve bowl shape, polish the exhaust ports and clean up an dags/cast marks, use your bigport cams for a bit more duration and lift, i simple bolted on my head with the cams, mine is still running stock boost on the S/C, i used to go door to door with a new manual Monaro CV8 all the way to about 160, then pull infront ever so slightly, now his front bar is on my rear bar in 2nd gear!!! it's actually a big difference you can definitly feel stright up! changed the way the ZE revs too..it pull feirce all the way up to 7G!!! so far i have found this to be the most reliable method of creating power..not jst running more boost, but to make the engine more efficient with the same boost...
my 2C
P.S. my car already did 13.9 and made just shy of 200hp @ fly, i had it running for 2 days then shat my diff.
[Updated on: Sat, 18 December 2004 23:57]
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