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Old 07-13-2005, 04:22 PM   #1
OB2
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Default STI ShortBlock VS RS stock block

I just ordered my STI short block and I asking myself what the best think to do???

The goald is to swap all the think in my actual setup on the short block, list there:

Performances modifications
Stock 2.5RS head
Lachute 3"/2,5" Turbo/Back Exhaust
Borla Gen.4 Header
Zero Sport Radiator Wind Deflector
Halley Fuel Pump (650 hp)
Cobb Tuning Cams
HKS Super Mega Flow Air Filter
HKS Intake
Go Fast Bits Blow Of Valves
ASR 2.25" Up-Pipe
ASR 3.0" Down-Pipe
WRX Intercooler
Turbonetics (T3/T4 Garrett) Turbo
Turbonetics Delta-Gate Wastgate
Turbonetics Manual Boost Controler(10psi)
Bell Engineering Fuel Pressure Riser
B&N Oil Engine Cooler
Unorthodox Racing Full Pulley Kit
WRX 420cc Injectors
Rising Rate Fuel Pressure Riser(new)
APEX'i S-AFC
Split Second TMC1

And I will swap, WRX 420cc Injectors, Rising Rate Fuel Pressure Riser, APEX'i S-AFC, Split Second TMC1 for a Hydra EM and midified WRX injectors (740cc).

THE BIG QUESTION IS.......... , shoold I bleed myself to the bone ans install forged piston and ported head or the performance gain will surprised me??? I want to run the STI setup at 19 to 20psi and my actual setup run at 10psi and did a Best time in 2004 of 13.344@103.157mph. How much HP the STI should have (on stock piston and RS head) and how much HP do you think my actual setup have???

Please NEED HELP
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Old 07-13-2005, 07:35 PM   #2
Matt Monson
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Well,
The Ej257 STi blocks can take a lot of boost and power, but they cannot take detonation. If you are going to spend any additional money, get yourself an E-manage and add proper tuning to your set up. You have a pretty potent combination of parts there, and you should be able to make plenty of power with a stock STi block and unported heads...
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Old 07-14-2005, 08:56 AM   #3
FastfreddyRs
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I believe the RS heads in stock form won't be able to handle 19Psi. they will float valves around 12-14. i would highly recommend Some cams and upgraded Valve springs and retainers. i Used TWE cams, springs, and retainers and the car feels much better now then before. the powercurve keeps pulling where before the car gets really flat on the upper RPM's.
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Old 07-15-2005, 12:37 AM   #4
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a local guy blew up his sti (cly 4) because of the emanage. he said it was fighting the stock computer on ignition timing and the computer won. i would research if your computer will do that as well before getting one.
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Old 07-15-2005, 01:13 AM   #5
Shaved
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Quote:
Originally Posted by sick1.8t
a local guy blew up his sti (cly 4) because of the emanage. he said it was fighting the stock computer on ignition timing and the computer won. i would research if your computer will do that as well before getting one.
Details? Wouldn't the stock ECU pull timing to help SAVE the car?
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Old 07-15-2005, 01:45 AM   #6
Hitokiri
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Quote:
Originally Posted by sick1.8t
a local guy blew up his sti (cly 4) because of the emanage. he said it was fighting the stock computer on ignition timing and the computer won. i would research if your computer will do that as well before getting one.
obviously your friend didn't know what he was doing.
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Old 07-15-2005, 08:56 AM   #7
DamienX
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Quote:
Originally Posted by OB2
I just ordered my STI short block and I asking myself what the best think to do???


THE BIG QUESTION IS.......... , shoold I bleed myself to the bone ans install forged piston and ported head or the performance gain will surprised me???
Please NEED HELP
I thought the sti shortblock came with forged pistons? What phase 2.5RS heads are you planning on running?
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Old 07-15-2005, 10:01 AM   #8
Wedge
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Quote:
Originally Posted by DamienX
I thought the sti shortblock came with forged pistons?
Nope. They are hypereutectic.
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Old 07-17-2005, 11:53 AM   #9
CUNNINGHAM
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Quote:
FastfreddyRs: I believe the RS heads in stock form won't be able to handle 19Psi. they will float valves around 12-14.
I have run 24lbs at 7800RPM and no valve float problems. I am not the only on either.
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Old 07-17-2005, 11:42 PM   #10
IllNastyImpreza
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Quote:
Originally Posted by CUNNINGHAM
I have run 24lbs at 7800RPM and no valve float problems. I am not the only on either.
wow

what cams where u running???
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Old 07-18-2005, 04:50 AM   #11
CUNNINGHAM
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Stock cams.
Should I have changed cams then I would have used a stronger spring.
Keep in mind every modification does have it's draw back along with it's benefits.
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Old 07-18-2005, 07:20 AM   #12
MrH00nel2
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you are choking yourself (shortblock) with the rs heads.... you will gain alot of hp with valvetrain/cams.

if not mistaken running stock wrx or rs heads on a sti block changes compression?
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Old 07-18-2005, 03:51 PM   #13
CUNNINGHAM
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Yes, the compression changes, it is now a 8.6:1 ratio. The heads I have are ported and flow very well. This set up has proven to be very powerful in the past. There are a select few of us with this setup making over the 400whp mark. I have yet to finish tuning because of other issues with the injectors I have but don't see the numbers out of reach. I know some will beg to differ but it has been done and proven reliable. I expect I will here a wrath about what I have written but I will soon be able to soon prove myself, what I have written
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Old 07-18-2005, 04:19 PM   #14
OB2
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I have Cobb Street mild cams do you think I will valve float problems. Do you think they are to radical fot that kind of boost???
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Old 07-18-2005, 04:28 PM   #15
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with that power goal , dont forget about your tranny
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Old 07-18-2005, 04:46 PM   #16
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Quote:
Originally Posted by CUNNINGHAM
I have run 24lbs at 7800RPM and no valve float problems. I am not the only on either.
I'm running 20psi on stock cams and heads currently
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Old 07-18-2005, 09:04 PM   #17
OB2
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For now I want to keep my stock tranny an be gentle with, and when it explode I will see
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Old 07-18-2005, 09:13 PM   #18
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Quote:
Originally Posted by 2RS's4US
I'm running 20psi on stock cams and heads currently
You wouldn't happen to have a dyno graph of that would you?

I ask cuz I know from experience how flat the stock cams can be on the RS heads up top.
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Old 07-19-2005, 09:09 AM   #19
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Quote:
Originally Posted by OB2
I have Cobb Street mild cams do you think I will valve float problems. Do you think they are to radical fot that kind of boost???
thoes cams should be fine to just drop in with little or no mods to the valves, etc and work fine. if im not mistaken

but remember if you get a larger cam will you need to get a stand alone ecu, but then again you wouldnt need one that big.


and someone did say, dont forget about your tranny. if i were you id keep that in mind.
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Old 07-19-2005, 12:12 PM   #20
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Quote:
Originally Posted by Wedge
You wouldn't happen to have a dyno graph of that would you?

I ask cuz I know from experience how flat the stock cams can be on the RS heads up top.
Unfortunately I don't, we just replaced the GT28r with a 20G last week and have only done street tuning on the LINK as we wait on the arrival of our Blitz SBC id v3
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Old 07-19-2005, 04:54 PM   #21
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I have a graph of the old engine with my car set at 18lbs and a 7000rpm redline.
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Old 07-19-2005, 05:52 PM   #22
Matt Monson
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Cunningham,
I think the only guys who will argue with you are the ones who haven't been able to pull it off, or who are just bench racers. A lot of people know that Xephyr hit 408 UNCORRECT WHP at 5000ft with his set up. He uses a stock Ej257 STi bottom end with stock DOHC '98 EJ25 heads. He has upgraded the springs, but otherwise the heads are on stock cams and unported. Anyone who tells you that you can't make real power on unported EJ25 heads is talking out their arse. They just haven't sorted out the formula to do it yet, and think that noone else can cuz they can't...
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Old 07-19-2005, 06:27 PM   #23
White 2.5rs
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well im switching to 257 heads mainly because of a way better aligned quench area, better meshing of the cooling ducts, and avcs

sure you can make power on the ej25 heads, but i want more
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Old 07-19-2005, 07:41 PM   #24
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Matt Monson, your hit the nail on the head. I have spoken to Xephyr receantly and he is currently running stock springs as he has had better luck with the stock as long as the are tested every 10,000 and replaced at 20,000 to 30,000 mile intervels. I have spoken to a lot of other people, with all types of cars, who have had more problem replacing oem valve springs with aftermarket springs, breaking them. Most of the test and replace there stock ones regularly. To them it's cheaper than blowing a engine. Some aftermarkets also need to be replace a frequent interval's. I am happy with my decision.
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Old 07-19-2005, 11:35 PM   #25
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Don't mean to hyjack, but, What head gaskets are you all using??? I am going to install my set up this fall and run small boost till I can afford a Link, then maybe get some maps from Xypher.
Matt, do you know what head gaskets they are using on the Turbo'd LGT at Sup Rupair.

And for everyone, is there a differance between the oil pumps?? EJ25 and EJ257

Great thread so far!!!

Erick
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