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· Registered
2002 Subaru Impreza 2.5 RS
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6 Posts
Discussion Starter · #1 ·
Hi I'm new to rs25.com but found this sight while trying to find help about modding my RS. Its a 2002 Subaru 2.5 RS so you know.

My question is in order to turn it into a a RS-T what do I need to do or what parts do I need. I've been doing a lot of research about it. So a new hood with a scoop. A top mount intercooler, the turbo of course the up and down pipes a cold air intake etc. What I was thinking or would this work getting a used turbo and intercooler etc from a 2002 WRX, like a wrecked one but those parts are still grade A. My other question is what will I need to upgrade in the 2.5. The 02 WRX is a 2.0l and mine is a 2.5l so will the .5 make up for the increased pressure etc that the turbo will create. I know I sound like a complete noob. Thats why I'm posting here.

Please don;t answer with trade in my RS and go get a WRX thats 4 years older then my RS etc because its to much work and trouble lol. But I'm a project person so this is what I do. I just want to know what I need etc or places where I can get answers on how to build it u know. My engine area is all stock if you are wondering. As far as the hood goes I was thinking of getting a carbon fiber hood with the scoop they go for about $500 online.


Thanks guys for the help.
 

· Registered
2002 Subaru Impreza 2.5 RS
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6 Posts
Discussion Starter · #3 ·
Ok so I've done more research and talked with some people that know what their doing lol as I don't know much about turbos etc. So if I don;t turbo my RS and rather got a new hood still with a scoop. Can I put a intercooler into still so the scoop is actually used and how would I hook the cooler up without the turbo. I've around online and can't find anything like that. I was also thinking about a cold air in like a K&N or a AEM. This would be one of my first upgrades any way. So if you guys know if I can do that or just have the scoop there just chillin lol.

Also do any of you know what the PSI output on 02 WRX turbo is. Just wondering if the 2.5l engine can handle a turbo off a 02 WRX. Looking at that as an alternative to a kit as I heard of a lot of people blowing their engines with the kits. Probably because their trying to put as much horse power in as possible. So 5 ps would be about where I want to be I'm assuming as the engine should be able to handle it just fine. Oh yeah my RS is an Auto and I heard the auto will be able to withstand the pressure etc better then a manual would? I'm not entirely sure about that. I have to many questions lol. Well if you think of any thing I might have forgotten. Oh wait yeah about the ECU, will I have to replace the comp. Or just get it reprogrammed if I drop a turbo into my RS. I will also have to get it tuned right.

Thanks Again
 

· RS-T
1999 Subaru Impreza 2.5 RS
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202 Posts
Firstly it really sounds like you want a hood scoop regardless of whatever route you take, so a carbon fiber hood would be a good starting point. About the intercooler, in basic terms, when you compress the intake charge beyond atmospheric pressure with the turbo and begin to run any boost the air will increase in temperature beyond the ambient temp. Thus an intercooler is placed between the turbo and the throttle body to help cool the compressed intake charge to a temperature closer to (but still above) ambient temp. Thus, running a intercooler without a turbo is useless because the intake charge is not being compressed beyond atmospheric pressure therefore the intake air is not being heated up, and the intercooler would effectivley do nothing (since it is impossible for the ambient air running over the fins of the intercooler to cool the intake air inside the intercooler below ambient temp.) Finally with your next question about boost on a 02 WRX, I think a USDM runs about 14.7 psi, probably a little bit higher, but dont quote me, if you run anywhere near that kind of boost on your 2.5rs say goodbye. The WRX has lower compression pistons, premium fuel etc. to compensate for this. If you were looking to turbo your 2.5RS 5 psi is a good place to start, (manual transmissions will only support about 3-4psi before the clutch starts to give out), but I have seen RS auto's upt to 7-8 lbs with proper supporting mods and engine management systems with lower comp. pistons. At the end of the day your going to get a CAI and cat back when reality sets in. Have fun with it though.
 

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2003 Outback Sedan H6
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2,386 Posts
I've read the RS engine is safe for up to 6 psi boosts.
It can be. I've seen people hit 8 PSI with no problems. But in all honesty its completely hit or miss. Truth is most people who boost the stock EJ25 end up blowing them up, and either do a complete motor build or swap in the end.
 

· Premium Member
2002 2.5 RS-T
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3,814 Posts
wooooo bugeyes represent.....

check out my member journal....it wont tell you everything but you'll get an idea....

why spend 500$ on a hood and then more on a top mount when u can buy an ebay front mount kit for under 300$ that works PERFECT on our cars....

now to help u i need a budget...how much u looking to spend.....if u dont have at least 3000$ u better either save up some more or forget it.....

now u can use wrx piping....but your crossmember isn't going to work....you'll need to either swap in a wrx crossmember, or notch and weld yours(i wont recommend this to anyone cause i dont want to be liable if something bad happens....but do what you do)....the just get wrx header(ebays are cheap, but fitment is hit or miss....i missed, but nonetheless it worked), wrx uppipe(some talk of certain ones not fitting, i know for sure the perrin fits)...wrx td04***(if you build your block DO NOT USE THE TD04, its too small), and wrx downpipe....lots of fun....

other option is to use custom up and downpipe.....u can find them for sale here sometimes, ludespeed or the subachad works, and then get a turbo that is flanged for those pipes(not sure what flanges they use....do some research on that if you go that route), the good thing about this is you dont have to mess with your crossmember, and IMO the turbo location is much more conveniant....

then u gotta feed oil and coolant to the turbo, for oil use the galley plug on the top of the block for the feel, and tap your oil pan(or valve cover if you dont want to pull engine) for return, for coolant just reroute the throttle body lines to the turbo...

then for fuel you'll need some wrx injectors (80$) and a walbro *(the walbro might not be necessary, but for 100$ u should)...it would also be beneficial to do the parallel fuel delivery mod (find it in the DIY section for more info)...

for intercooler like i said just go ebay FMIC kit...cheap and works great.....

next is engine management.....be prepared to spend the dollars :(.....what u get depends on your plans....if you're leaving the block stock you can get away with emanage ultimate for low boost.....it'll run u about 450$ used (gotta hunt a bit)...if you are planning on running more boost u *can* get away with the emanage ult, but i would go with standalone, i use hydra (1800$) and LOVE it....theres also the link standalone which will work well for higher boost but is harder to find....

next for the block.....leave it stock you can run 5-6 psi safely with a small turbo(td04 would be perfect, and dirt cheap)......any more boost you will most likely run into trouble long term.....high boost (10+ lbs) will destroy your block most definetly....the problem is the blocks compression, 10:1 is too high for much boost. But at the same time low boost on 10:1 will get you good results (200ish whp) and will put u on par with ej205 wrxs.....
the other option is to swap or build your block....i swapped in a ej255 block, and am now running a 18G at 17-18 lbs and love it....i destroy stock STIs all day long....as well as run circles around even fairly heavily modded wrxs.....or another option is to rebuild your RS block with sti internals(search for brydons thread about this....brydon is the man).....

personally i would try to do something like my build....ej255 block, standalone and 18G(even though mxpunk says i need bigger turbo....but the 18g is plenty fun....i dunno im starting to think maybe he;s right.....lol...nevertheless the 18G is a lot of fun...wow im rambling).....

anyway....theres a few more things i'm leaving out.....but that should get u started...anymore qquestions, post em up!....

so a couple questions: what are your goals? HP wise....
how much do you want to spend?
what are you comfortable with? would u be willing to split your block? pull your engine?

ps i noticed your in vancouver WA.....i'll be in portland at the end of this month....hit me up closer to then and i'll let u check out my car and help explain some stuff to you.....
 

· Premium Member
2002 2.5 RS-T
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3,814 Posts
It can be. I've seen people hit 8 PSI with no problems. But in all honesty its completely hit or miss. Truth is most people who boost the stock EJ25 end up blowing them up, and either do a complete motor build or swap in the end.
well put.....but most people do not turbo the block properly and cut corners.....5psi is perfectly safe if you DO NOT CUT CORNERS....spend the money, or you'll spend it later type deal......

but at the end of the day i really think at least some sti internals gives u a lot more piece of my...and really doesn't add too much to the costs of the build....

:hydrogen:
 

· Registered
1998 Subaru Impreza RS - RBP
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1,762 Posts
but at the end of the day i really think at least some sti internals gives u a lot more piece of my...and really doesn't add too much to the costs of the build....

:hydrogen:
Yeah, it's hard to beat stock STi pistons and rods for only ~$250...
It's what I'm currently doing to my motor.
 

· Registered
2002 Subaru Impreza 2.5 RS
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6 Posts
Discussion Starter · #10 ·
Hey Jeff I was told you were the guy to talk to. Thanks for the suggestions and tips. I do have a nice budget but not sure if its worth the risk. I don't do any sort of racing just general cruising around town lol. I also go mudding out around Adams and St Helens on the dirt roads out there. A lot of fun lol. Yeah for the ralley racing. Any way so I think I might just go with what flame was saying. Put a good cold air intake and a better exhaust cat back system in it.

I've helped my friends out with modding their cars quiet a bit. One of my friends has a VW Scirocco that we replaced the trans on and have been doin a lot of work on very nice car I believe its an 84 or something.

So I have done a lot of engine work but putting a turbo in an RS just for 30 more HP isn't worth it in the long run. I might still do it but time and cost wise I see why they say just to trade in your RS for a WRX if you want a turbo charged car. So besides from a cat back and CAI what other performance mods would you guys suggest. The hoodscoop is out then since its not practical and I'm not spending $600 some od bucks for a new hod etc for something that is simply cosmetic.

I don;t remember where I heard this, but someone told me that they make CAI that are made for your scoop. I've around online couldn't find anything. No I'm not going back to trying to get a scoop. I got my RS for a reason well the main being the 5000 extra for an STI wasn't just sitting there lol. Ok now I'm rambling, so yeah I was also thinking of getting some better tail and head lights. My back right tail assembly is cracked and has been that way since I bought it. So either way I am buying new AM tailights. Maybe you guys might know but I found the sweetest looking headlights for the 02 imprezas, I'm just not sure of the manafactuer that or they're probably custom. Here is a link http://www.designercars.net/membercars/3224.

If you have any cool looking headlights you want to suggest just post a link . In the way of performance mods if I don't go the turbo rout what do you guys suggest doing. New struts etc, CAI, nice cat back. I think thats everything thanks again guys for the suggestions and I'll keep looking around.
 

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1998 Subaru Impreza RS - RBP
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1,762 Posts
Get yourself a nice clutch and a lightweight flywheel.
Also, a borla header is always a pleasant addition to the exhaust. :)

You could also spend a couple hundred bucks and get your cams done by Delta Cams...
 

· Premium Member
2002 2.5 RS-T
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3,814 Posts
30 whp? stock block + 5psi will put u at around 200 WHEEL horsepower....stock is about 130.....and torque is crazy....and then with some minor internal work you'll be able to push 350whp no problem....but yeah...it is definetly a lot of work and money....but its definetly worth it when u finish.....

eitherway.....i would go with some delta regrinds, emanage ultimate or perfect power 6...some borla headers for sure (sound awesome), and then little stuff like intake, exhaust, etc....

but before that....SUSPENSION.....if you're not going turbo suspension is the way to go IMO....

oh...and why not some nitrous? damnit i wanna see some nitrous on an RS.....(make sure u get a pp6 and tune for the nitrous though)....i think a 50 shot + the delta regrinds would be all kinds of fun.....

gah...maybe its time for me to buy another RS ....:D
 

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2005 Subaru Impreza RS 5MT
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4,588 Posts
You don't have to do a custom build or trade in for turbo power; you can always do a drivetrain swap, which gives you factory reliability and mileage, plus much more potential.

The intake you're talking about it the gravelsport; every now and again, they go up for sale used, but they haven't been made in years. You would most likely have to rig your own.

If you're just lookin' to cruise, why look for more power at all? It just burns up more gas. ::shrug::
 

· Registered
2002 Subaru Impreza 2.5 RS
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6 Posts
Discussion Starter · #15 ·
Hey guys I've been some more research on what you've given me. I think I might go with a CAI, cat back, better springs etc. I need to replace my tailights to as one is cracked really bad now from a idiot with a pick up tapping me. He just killed my light essembly didn't touch the rest of the car. Besides from that is there any other performance mods I can do besides from the turbo overhall that will increase my HP. Also in my previous do any of you guys know what those front headlightsd are called or what company makes them. I posted the url there.

Well thanks again guys. Oh yeah thanks so much Jeff you anwswered alot of my questions. Oh yeah Jeff where can I find an engine block if I was to go your rout.
 

· Premium Member
2002 2.5 RS-T
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3,814 Posts
Well thanks again guys. Oh yeah thanks so much Jeff you anwswered alot of my questions. Oh yeah Jeff where can I find an engine block if I was to go your rout.
nasioc classifieds u can find sti blocks for about 800-900$ used but in good shape....

i bought mine for like 350$ but it had a spun bearing...so i rebuilt it....

you can however buy a new sti shortblock for about 1700$....www.thekingofparts.com has em...

or if u keep an eye on ebay u can find them brand new for about 1000$ sometimes...that is your best bet if u dont want to rebuild...

the two main things in my build was the hydra and the block.....after that its just a bunch of little stuff that u can find dirt cheap on classifieds....

with hydra(or link) and the sti/wrx(2.5L) shortblock you have replaced the 2 main weak links in the RS engine.....throw some minor headwork(springs mainly) and you can safely push 400-450 whp all day long.....and at the end of the day you will still be cheaper than a ej205 swap....and make much better power....

i dont see why people dont go this route more often(as opposed to a swap)...i guess its just the work involved:run:
 
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