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Old 08-28-2019, 02:00 AM   #1
jamdun17
Scooby Newbie
 
Member#: 325805
Join Date: Jul 2012
Default What's "worth it" mods to make big power?

I'm currently building my ej257, have the basics bought already.
Closed decked block from IAG
Wiesco Pistons
Manley turbo tuff rods
280 cams
+1 mm over valve b25 heads
Gtx3582r .82 t3
Competition twin disk
Water to air intercooler
Currently have a perrin rotated turbo kit (might be looking to trade or sell this soon)

Up coming parts
Twin Walbro 450's -10 an lines
2000cc injectors
625+ headstuds
Je proseal head gaskets
Ms3 pro plug and play

What else would you all recommend I spend money on to meet my goals of 750-800 whp? Can I hit those numbers with a T3 housing ? Can I hit those number with a Perrin catted rotated turbo kit ? Is there any unforeseen or small non-talked about issues ? Can the stock oil pump keep up to ~8000 rpm?

I was thinking of an intake like the ams to help out with the top end and I'm partial to the subbie rumble so would like to keep some kind of UEL header but I havent seen anyone making those numbers with UEL.

Also anyone have pics of a top mount with an AMS intake, or at least an AMS intake in a gc8?
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Last edited by jamdun17; 08-28-2019 at 02:19 AM.
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Old 08-28-2019, 10:17 AM   #2
subydude
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Member#: 80649
Join Date: Jan 2005
Chapter/Region: South East
Location: Columbia, SC
Vehicle:
2000 2.5 Auto-X RSTi
Dusty

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Lots of details in other threads that answer your questions. You'll be pushing a lot of boost to make that much whp on that turbo. It's very unlikely you'll do it on a catted exhaust. The stock oil pump can do 8k. The 2.5i intake manifold flows pretty much as well as other aftermarket ones. You will not make nearly as much power on UEL as you will on EL headers, so switch now if you want to make power.
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Old 08-28-2019, 01:40 PM   #3
TDagen
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Join Date: Nov 2007
Chapter/Region: MWSOC
Location: Xona 7864 UHF
Vehicle:
2002 WRX
V9 6mt R180 Brembos

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Quote:
Originally Posted by subydude View Post
Lots of details in other threads that answer your questions. You'll be pushing a lot of boost to make that much whp on that turbo. It's very unlikely you'll do it on a catted exhaust. The stock oil pump can do 8k. The 2.5i intake manifold flows pretty much as well as other aftermarket ones.
+1 Thats gonna be most if not all of the boost with that turbo, 40psi or more. I also agree about the catted exhaust, get rid of it.

OP FWIW I made over 600whp (629whp road dyno, dynojet setting) at 26-28psi on the hta86 running a stock header/stock crosspipe into a 2.2 I.D. up pipe. It was fueling limited or I would have kept going. Numbers were where I expected them to be. If I was making around 10whp per psi and added 12 more psi (40psi) that would have put the numbers square at 750whp on a 78lb per minute turbo. Basically right where they should be. Now would I make it to 750 on the stock header? Most likely imo, but nobody runs it with big power setups making it hard to prove.

I plan to fab up my own crosspipe and run the stock header again this time around. Worked great last time.
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Old 08-28-2019, 02:08 PM   #4
StarkWRX
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Join Date: Sep 2017
Location: Morgantown, WV
Vehicle:
2006 WRX
World Rally Blue

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Out of curiosity what cams did you get?
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Old 08-29-2019, 10:23 PM   #5
stu
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Member#: 25768
Join Date: Oct 2002
Chapter/Region: RMIC
Location: CO springs
Vehicle:
2003 GEN2 GTX35 40++
SL performance, 2.34 LR

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On my setup the Equal length header(HKS) helped a ton up top above 35psi. Also if your gonna be running 800whp you will be popping axles left and right so you may want to look at some dss 1k axles. Don't waste your time with anything under 800 whp rated. Also not sure how long your head gaskets are gonna last on the 625+ studs at 800.
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Old 08-30-2019, 11:24 AM   #6
subaru_gc8
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Join Date: Nov 2002
Chapter/Region: SCIC
Location: Orange County CA
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2004 WRX wagon
silver

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800 is a lot for a little 4 banger..I would talk to IAG to get a build plan instead of taking to the internet. 800 is a whole different game than like most of us are playing at 400-500. but with that, you are probaly going to run into transmission strength problems. you probably going to have to go with the widest gears you can find. as for head studs I would go wtih 14 mm. plus at those power levels your block probably isnt going to last very long

and fueling is going to be an issue as well. not delivery or injectors but all the other stuff like lines rails and regulator
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