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Old 01-16-2006, 02:35 PM   #1
Big_DeWeY
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Default q's on 2.5l STi Block w/ WRX heads?

Well I'm almost positive I'm gonna have to tear apart my motor again (long story don't ask) and im sick of this worrying about ej205 internals and its gonna cost me almost as much to get an STi shortblock as it will to get my bottom end rebuilt so that sounds like the ticket.

Question 1. Will my WRX heads mate up O.k.? What headgasket am I gonna need to run?

Question 2. What turbo would be the best for this setup to make 300-350whp with the least amount of lag?

Question 3. What engine management do you recommend for this? I have a buddy that keeps telling me to use an AP over a UTEC but I hear so many good things about the UTECs.

Thanks guys
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Old 01-16-2006, 02:43 PM   #2
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Quote:
Originally Posted by Big_DeWeY
Well I'm almost positive I'm gonna have to tear apart my motor again (long story don't ask) and im sick of this worrying about ej205 internals and its gonna cost me almost as much to get an STi shortblock as it will to get my bottom end rebuilt so that sounds like the ticket.

Question 1. Will my WRX heads mate up O.k.? What headgasket am I gonna need to run?

Question 2. What turbo would be the best for this setup to make 300-350whp with the least amount of lag?

Question 3. What engine management do you recommend for this? I have a buddy that keeps telling me to use an AP over a UTEC but I hear so many good things about the UTECs.

Thanks guys

Yes. Stock Gaskets

I would run an fp green.. Very responsive on the 2.5 and will reach those goals with ease.

Both are good. It is a matter of preference.. Would you get the street tuner, and tune the car yourself? Is there local utec tuners? Local pro tuners? Run alot of race gas?
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Old 01-16-2006, 02:49 PM   #3
LIQUIDSK8S
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Quote:
Originally Posted by cronic
Yes. Stock Gaskets

I would run an fp green.. Very responsive on the 2.5 and will reach those goals with ease.

Both are good. It is a matter of preference.. Would you get the street tuner, and tune the car yourself? Is there local utec tuners? Local pro tuners? Run alot of race gas?
Don't you need to run a STI 2.5 headgasket?
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Old 01-16-2006, 03:12 PM   #4
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Check with Quirt Crawford I think he has a WRX to Sti block head package for gaskets etc....normal gaskets alone=high compression.

Im running double thick 2.5 gaskets. Its not preffered on the boards but they have worked just fine for me. 30000 miles at 8.5:1 and going strong Im at 390 WHP.

BTW Im running Hydra and GT30R
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Old 01-16-2006, 03:13 PM   #5
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Yup 2.5l Sti gaskets will put you at 9.17:1 compression ratio according to Ron at AxisPowerRacing. If you get Cometic's .051 thick head gaskets you'll drop to 8.5:1. This is what I'm currently running. For a turbo I've got a VF22 for real quick response. I run autocross so I didn't want crazy lag. For power output I've put 305whp/303tq on a dynojet here in Miami. This however was on my previous setup of 9.17:1 compression. Since I've lowered the compression, I only have 400miles on the motor and have yet to tune it. Oh, and I'm using a UTEC.
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Old 01-16-2006, 03:26 PM   #6
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Quote:
Originally Posted by LIQUIDSK8S
Don't you need to run a STI 2.5 headgasket?
Yes, what i meant by stock gaskets. Ie not aftermarket.

Pacobeagle- Let us know how those cometics hold up.. I know they are supposed to be revised now.
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Old 01-16-2006, 11:00 PM   #7
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thanks.

so what i got out of this was
1. there gonna mate but were up in the air about headgaskets. WRX/STi/Aftermarket (cometic)?

2.FP green or vf22. I've heard of lag issues with the 22. Is that cured by the extra half a liter?

3.I don't have acces to race fuel nor do I want/care to use it. My nearest Dyno is away's away. I would like to tune it myself but I have a friend who says we can road tune it and his buddy can email me maps for the AP. I'm a little leary on that though, I mean he's not in the car. Basicly what he said was that the accesport was better becasue it reflashes the ECU instead of lying to it liek the UTEC. any input?
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Old 01-16-2006, 11:27 PM   #8
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I have been looking into this block swap and I plan on running the stock gaskets because of the higher compression ratio...
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Old 01-17-2006, 07:09 AM   #9
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I ran an auto-x this past Sunday and all is running fine. The drive up to the event was some 76miles so I figure I put in some 175miles total. Gas mileage was a little low but I spent a lot at the event. Again, I'm running on my previous tune of 9.17:1 compression. It's a little sluggish but I am sure that I can cure that a little with timing corrections.
I forgot to mention that I'm running an APS DR650. If you run the stock gaskets, I was running a max boost pressure of about 18psi.
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Old 01-17-2006, 08:25 AM   #10
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Quote:
Originally Posted by Big_DeWeY
thanks.

so what i got out of this was
1. there gonna mate but were up in the air about headgaskets. WRX/STi/Aftermarket (cometic)?

2.FP green or vf22. I've heard of lag issues with the 22. Is that cured by the extra half a liter?

3.I don't have acces to race fuel nor do I want/care to use it. My nearest Dyno is away's away. I would like to tune it myself but I have a friend who says we can road tune it and his buddy can email me maps for the AP. I'm a little leary on that though, I mean he's not in the car. Basicly what he said was that the accesport was better becasue it reflashes the ECU instead of lying to it liek the UTEC. any input?
The lag issues you're talking about are related to 2.0l. A VF22 is good for instant boost, lots of torque, but limited top-end. 2.5l are a completely different motor to drive. Any version of a TD06-20g will give you excellent spool characteristics and good top-end. The 2.5l guys have known that the TD06 turbine wheel mated with a larger hotside turbo gets great results on 2.5l.
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Old 01-17-2006, 08:29 AM   #11
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Quote:
Originally Posted by Big_DeWeY
Well I'm almost positive I'm gonna have to tear apart my motor again (long story don't ask) and im sick of this worrying about ej205 internals and its gonna cost me almost as much to get an STi shortblock as it will to get my bottom end rebuilt so that sounds like the ticket.

Question 1. Will my WRX heads mate up O.k.? What headgasket am I gonna need to run?

Question 2. What turbo would be the best for this setup to make 300-350whp with the least amount of lag?

Question 3. What engine management do you recommend for this? I have a buddy that keeps telling me to use an AP over a UTEC but I hear so many good things about the UTECs.

Thanks guys
AP and UTEC's are both fine. However, you would have to get a protune AP to compare. Standard AP's flash pre-set maps, and are not adjustable beyond that. You will need the pro-tune or a TXS UTEC to fine tune your EM. I have a UTEC and am very happy with it.
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Old 01-17-2006, 10:06 AM   #12
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Quote:
Originally Posted by Newbie Subie
Check with Quirt Crawford I think he has a WRX to Sti block head package for gaskets etc....normal gaskets alone=high compression.

Im running double thick 2.5 gaskets. Its not preffered on the boards but they have worked just fine for me. 30000 miles at 8.5:1 and going strong Im at 390 WHP.

BTW Im running Hydra and GT30R
Good choice. A GT32 or a CP32 from Crawford can work to.

THe stock ecu would work, but I would get a Hydra first.

Check them out
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Old 01-17-2006, 07:23 PM   #13
LIQUIDSK8S
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Im finishing up my block at the moment. Im running a 2.5 block with the crank drilled by Axis and balanced. Im using Mahle pistons.....which put my CR to 8.5:1 .......if I was running USMD heads.....instead im running JDM STI heads.........not sure what my CR is going to be but it should be around 9:1 running OEM gaskets.

Anyone know for sure how to find out what my CR will be?
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Old 01-17-2006, 10:29 PM   #14
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Im running a 2.5l block, stock heads, STI headgasket, FP18G, tuning with Haltech Inteceptor

still pretty untuned, and at only 7psi, boost comes on like crazy fairly early- Ill get back with what it comes on fully at.
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Old 01-18-2006, 02:21 PM   #15
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thanks

so nothing yet on what head gasket i should use for this?
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Old 01-18-2006, 02:23 PM   #16
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According to Ron at Axis, my 2.5 with Mahle Pistons and JDM STI heads.....my CR with stock headgaskets would be 9.5:1.

Im thinking of running a few diff cometic headgaskets.....one would put me at 9:1 and the other 8.8:1. I know my old setup with the v8 JDM STI it ran at 9:1 CR.......but it was also a 2.0 while the 2.5 might have a lil harder time at that CR rather then going to 8.8:1 and having wicked response and some room up top......decisions decisions.
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Old 01-18-2006, 05:19 PM   #17
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my vote is for the 8.8 or 9.0. I miss my response. I've yet to tune the car so I can't really tell.
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Old 01-18-2006, 06:06 PM   #18
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ok im still lost here. Im gonna need a cometic headgasket then. I want to run as close to a stcok CR as possible and i know that thats under 9.0. Where do i get the gasket to do this?
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