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Old 01-17-2008, 12:20 AM   #1
alex02wrx
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Default 02 WRX 2.0L upgrading to STI 2.5L block, concerns/Suggestions?

I own a 2002 Subaru WRX 2.0 L, Im in the process of buying an STI 2.5L block to replace the 2.0 block. I've been told by many people that the stock heads will fit and work fine with it. I will be upgrading the fuel pump, and either modifing the injectios to 850 cc's or replacing them with pink STI injectors as well as getting the car tuned. Do any of you have any suggestions and should I be concerned about anything going this route?
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Old 01-17-2008, 01:11 AM   #2
sleeperrex
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Quote:
Originally Posted by alex02wrx View Post
I own a 2002 Subaru WRX 2.0 L, Im in the process of buying an STI 2.5L block to replace the 2.0 block. I've been told by many people that the stock heads will fit and work fine with it. I will be upgrading the fuel pump, and either modifing the injectios to 850 cc's or replacing them with pink STI injectors as well as getting the car tuned. Do any of you have any suggestions and should I be concerned about anything going this route?
I'd talk to your potential tuner. Stock 2.0 heads and 2.5 block can be difficult to tune. Your compression will be raised with the OEM STI Gasket. Not a big deal but something to be aware of. The setup runs relatively lower timing because of the higher compression.

Some things to consider would be pistons to make up for the difference in compression or a different gasket like maybe the cometec with ARP studs. Although they seem to have their own issues according to some people.
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Old 01-19-2008, 02:10 PM   #3
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Just search the forum for 'hybrid'.
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Old 01-19-2008, 05:12 PM   #4
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The higher compression should be no problem for a good tuner. More difficult to tune, yes, impossible? No. My hybrid is a tad over 9:1 and I'll tell you it's great for around town off-boost driving. The TD04 will start to wheeze above 5500rpm but it will work fine and spool very fast. You DO NOT need different pistons or gaskets. Run the stock STI gasket and you are GTG. ARP studs are a waste of money unless you are going to be making big power. One thing that I would say you MUST do is either gut your factory uppipe or buy a catless aftermarket one. You DON'T want to leave that cat in their. Get yourself a factory service manual on Ebay for 15 bucks and sleep well at night
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Old 01-19-2008, 06:44 PM   #5
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^^ Agree 100% The TD04 spools up so fast on this type of build it needs to be reined in quite a bit. A good tuner will be able to deal with it. Hopefully you have someone in your area...

I used DrinkAV8's thread as a guide but there are quite a few if you do a search. You have a PM.
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Old 01-19-2008, 09:58 PM   #6
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Another hybrid owner here. It was definitely one of the best mods I've done. You don't need to replace the pistons but I highly recommend it. If you have the money, you might as well since it would be more expensive down the road. It's just a reliability thing. I put about 20,000 miles on my setup with stock pistons and now it's on the shop getting some wiseco's installed due to low compression on 3 cylinders. With the stock turbo the engine will be prone to detonation due to how fast it spools and let me tell you, the stock td04 spooled instantly with the added displacement and compression ratio.
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Old 01-20-2008, 12:11 PM   #7
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Awesome, thanks for all the help. BTW, I've talked to a few performace shops and they suggested I go with a cosworth 100mm bore 1.1mm HeadGasket. Should install this or stick with a stock STI head Gasket?
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Old 01-20-2008, 12:39 PM   #8
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Quote:
Originally Posted by alex02wrx View Post
Awesome, thanks for all the help. BTW, I've talked to a few performace shops and they suggested I go with a cosworth 100mm bore 1.1mm HeadGasket. Should install this or stick with a stock STI head Gasket?
Cosworth, wow. Can't imagine their are many people running Cosworth headgaskets on these boards with a hybrid setup. Interesting suggestion.

Unless they have done a lot builds with Cosworth gaskets, i'd stick to the STI oem. Maybe they could provide you with references on people running them and see what there thoughts are. You may not want your car to be a guinea pig based on things they may want to see.

I believe you basically have 3 options
1) Oem STI gasket
2) Cometic gasket
3) Different piston sizes.

Every tuner, builder, seems to have there own opinion on things. It really comes down to who is doing the work. Just do your research and ask a lot of questions then make your final decision based on your own judgement. There is a lot of good info on these boards but sometime conflicting opinions.

As far as low-end grunt with a hybrid. There is a significant drop off without running AVCS. Better than EJ205, but not STI type lowend. Even with higher compression. Higher compression leads to more detonation.

Last edited by sleeperrex; 01-20-2008 at 12:45 PM.
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Old 01-20-2008, 03:51 PM   #9
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Can you run after market 02 ej205 up pip and downpipe with a hybrid setup? Thanks
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Old 01-20-2008, 07:55 PM   #10
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Quote:
Originally Posted by xxxjuhstenxxx View Post
Can you run after market 02 ej205 up pip and downpipe with a hybrid setup? Thanks
Everything is basically the same but the displacement. You will be fine with all your current mods.
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Old 01-20-2008, 11:08 PM   #11
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Quote:
Originally Posted by sleeperrex View Post
Cosworth, wow. Can't imagine their are many people running Cosworth headgaskets on these boards with a hybrid setup. Interesting suggestion.

Unless they have done a lot builds with Cosworth gaskets, i'd stick to the STI oem. Maybe they could provide you with references on people running them and see what there thoughts are. You may not want your car to be a guinea pig based on things they may want to see.

I believe you basically have 3 options
1) Oem STI gasket
2) Cometic gasket
3) Different piston sizes.

Every tuner, builder, seems to have there own opinion on things. It really comes down to who is doing the work. Just do your research and ask a lot of questions then make your final decision based on your own judgement. There is a lot of good info on these boards but sometime conflicting opinions.

As far as low-end grunt with a hybrid. There is a significant drop off without running AVCS. Better than EJ205, but not STI type lowend. Even with higher compression. Higher compression leads to more detonation.
Not if you have a good tuner. The stock ECU WILL run quite well until you get a tune. I wouldn't beat on it, but it will run better than you think.
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Old 01-20-2008, 11:12 PM   #12
sharpe
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just did this swap but already had the vf39. getting tuned next monday by SS. love the new power. running stock 2.0 heads on the 2.5 block...no issues
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Old 01-21-2008, 05:38 AM   #13
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are there off the shelf forged lower compression pistons people are using for these hybrids? meaning lower comrpresion than stock sti so a thicker hg isnt needed.
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Old 01-21-2008, 12:24 PM   #14
Gixxer1K
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Why would you want to do that? That is just spending more money.
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Old 01-21-2008, 12:25 PM   #15
Gixxer1K
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Quote:
Originally Posted by sleeperrex View Post
Cosworth, wow. Can't imagine their are many people running Cosworth headgaskets on these boards with a hybrid setup. Interesting suggestion.

Unless they have done a lot builds with Cosworth gaskets, i'd stick to the STI oem. Maybe they could provide you with references on people running them and see what there thoughts are. You may not want your car to be a guinea pig based on things they may want to see.

I believe you basically have 3 options
1) Oem STI gasket
2) Cometic gasket
3) Different piston sizes.

Every tuner, builder, seems to have there own opinion on things. It really comes down to who is doing the work. Just do your research and ask a lot of questions then make your final decision based on your own judgement. There is a lot of good info on these boards but sometime conflicting opinions.

As far as low-end grunt with a hybrid. There is a significant drop off without running AVCS. Better than EJ205, but not STI type lowend. Even with higher compression. Higher compression leads to more detonation.
Maybe a tiny bit.

http://forums.nasioc.com/forums/show...2&postcount=41
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Old 01-21-2008, 07:03 PM   #16
doug*E*fresh
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i jus did the swap when the 2.0 was pulled out all sorts of **** was trash and costed alot more money than planed.
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Old 01-21-2008, 11:43 PM   #17
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As I am in the same boat (EJ257 swap), I will be reviewing this thread
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Old 01-22-2008, 12:08 AM   #18
sleeperrex
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Quote:
Originally Posted by Acostafan View Post
Not if you have a good tuner. The stock ECU WILL run quite well until you get a tune. I wouldn't beat on it, but it will run better than you think.
Everybody doesn't have access to a great tuner. Having somebody tuning a hybrid with little to no experience is asking for trouble.
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Old 01-22-2008, 12:13 AM   #19
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Quote:
Originally Posted by Gixxer1K View Post
Confused, is that a hybrid dyno plot? I don't see anything in there refering to a hybrid.
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Old 01-22-2008, 03:19 AM   #20
alex02wrx
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Quote:
Originally Posted by sleeperrex View Post
Everybody doesn't have access to a great tuner. Having somebody tuning a hybrid with little to no experience is asking for trouble.
Ill be having Worldoneperformace.com do all my tunning. about 3-4 hrs away. Closest I got to a tuner.
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Old 01-22-2008, 10:04 AM   #21
sleeperrex
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Quote:
Originally Posted by alex02wrx View Post
Ill be having Worldoneperformace.com do all my tunning. about 3-4 hrs away. Closest I got to a tuner.
I'm sure worldone has done plenty of hybrids. You'll enjoy it
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Old 01-22-2008, 11:06 AM   #22
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Quote:
Originally Posted by sleeperrex View Post
Everybody doesn't have access to a great tuner. Having somebody tuning a hybrid with little to no experience is asking for trouble.
you being in sas diego i can say for sure Gruppe-S in SAN FRAN area i know its not close but its the closest I personally know of that could do it for sure.
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Old 01-22-2008, 11:23 AM   #23
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Quote:
Originally Posted by sleeperrex View Post
Confused, is that a hybrid dyno plot? I don't see anything in there refering to a hybrid.
Yes it's a hybrid
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Old 01-22-2008, 11:24 AM   #24
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Quote:
Originally Posted by alex02wrx View Post
Ill be having Worldoneperformace.com do all my tunning. about 3-4 hrs away. Closest I got to a tuner.
Do they have a dyno yet?
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Old 01-22-2008, 09:00 PM   #25
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Originally Posted by doug*E*fresh View Post
you being in sas diego i can say for sure Gruppe-S in SAN FRAN area i know its not close but its the closest I personally know of that could do it for sure.
Garage Tuning did mine. There a lot closer in Anaheim.
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