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Old 04-30-2004, 09:57 PM   #1
AntonioS
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Default engine building questions!!!

Forged sti shortblock with RS DOHC stock heads will it flow good??? and I'm planning on running a 20g turbo with a gc8 swap my only doubt is the oil return line and where you guys pass the silicone turbo inlet hose??? using rs intake manifold will it fit???DOHC heads will the hold 7000rpm using stock components???
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Old 05-01-2004, 07:01 AM   #2
PHATsuby
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Antonio, come on man you have been here a while, you know to use the search.

first, if you are getting a USDM STi block, it is not forged, DOHC will flow ok, SOHC is known to flow better though.

not real sure what you are asking about the silicone inlet hose, i am assuming you mean passing the intake under the manifold, i think its possible but you need to relocate the power steering resevoir. DOHC MAY hold 7k rpm but i wouldnt recommend it, you already have to turn more mass being DOHC which doesnt help it. Graham is running a 7k redline on the SOHC heads though with only upgraded springs and retainers.

hope some of that helps

Ben
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Old 05-01-2004, 12:19 PM   #3
squirrelmasta
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Stock valve train will float above our red line. you need to up grade your springs before you can take the red up. Peace.
-Eli
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Old 05-01-2004, 07:34 PM   #4
totoherbs
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Quote:
Originally posted by PHATsuby
Antonio, come on man you have been here a while, you know to use the search.

first, if you are getting a USDM STi block, it is not forged, DOHC will flow ok, SOHC is known to flow better though.

not real sure what you are asking about the silicone inlet hose, i am assuming you mean passing the intake under the manifold, i think its possible but you need to relocate the power steering resevoir. DOHC MAY hold 7k rpm but i wouldnt recommend it, you already have to turn more mass being DOHC which doesnt help it. Graham is running a 7k redline on the SOHC heads though with only upgraded springs and retainers.

hope some of that helps

Ben
Yup... I would go wrx heads and ej257 short. And if you have money later 2.5sti cams arnt a lot of moeny and a port and polish wouldnt hurt.

I would not use RS DOHC heads with out working done to them near 7k. The SHOC flows a good deal better and if your not going to rev the motor out to 7k then you dont have to spend anything on the heads.

This has been talked about before...
http://forums.nasioc.com/forums/show.../t-448397.html

http://forums.nasioc.com/forums/show.../t-291231.html

http://forums.nasioc.com/forums/show...hreadid=424055
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Old 05-01-2004, 08:18 PM   #5
AntonioS
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Im planning on cp pistons pauter rods and SOHC heads port and polish with spring and retainers and some twe cams. and a 5zigen header with a turboxs downpipe and a 20g or vf34 work by deadbolt that they modify the the front of the turbo with 18g turboparts
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Old 05-01-2004, 08:24 PM   #6
totoherbs
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I say lose the header if you can, stock iron > stainless steal. Are the twe welded cams? Becarefull with welded cams....
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Old 05-01-2004, 08:44 PM   #7
AntonioS
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why loose the header? I'm changing the Xmember so I can use wrx headers and was planning on using the 5zigen one. I have header many good remarks about TWE products which they speciallize in RS.
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Old 05-01-2004, 09:03 PM   #8
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Headers will slow down the spool of the turbo and they lose power when they cool because they are stainless steel vs iron stock ones.
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Old 05-01-2004, 09:09 PM   #9
no-coast-punk
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Quote:
Originally posted by totoherbs
Headers will slow down the spool of the turbo and they lose power when they cool because they are stainless steel vs iron stock ones.
no no no!
You are right about the heat loss thing, but get a good coating. Well designed headers drastically increase gas extraction which = more flow velocity, which = faster spool up. Try good headers, you'll like it
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Old 05-01-2004, 10:48 PM   #10
totoherbs
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Quote:
Originally posted by no-coast-punk
no no no!
You are right about the heat loss thing, but get a good coating. Well designed headers drastically increase gas extraction which = more flow velocity, which = faster spool up. Try good headers, you'll like it
Like? There isnt one manufacturer ive heard of that desnt say thier headers will increass lag. And while coatings will help keep the heat in its still no where near as good as iron with the stock heat shield.
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Old 05-01-2004, 10:54 PM   #11
squirrelmasta
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VF34 Vs a 20 G??? these are quite the different turbo's and i don't know if they have the same bolt ups??? might. Peace.
-Eli
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