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Old 04-14-2004, 04:09 PM   #1
ehlpitel
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Default 2.5rs Turbo

what is the cubic inch displacement of a:
2.5rs and a 2.2 impreza
what is the compression ratio of a:
2.5rs and a 2.2 impreza
What is the volumetric effieciency for:
2.5rs and a 2.2 impreza
are there any parts interchangable between the imperza rs2.5/2.2 and any subaru factory turbos such as turbo headers. do people who turbo the impreza rs/2.2 usually put the intercooler on top or in the front?
thanks in advance
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Old 04-14-2004, 05:16 PM   #2
squirrelmasta
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Um, well to start, do some searching and you could prob find most of those anwsers.

Compression of the 2.5RS's are said to be 10:1 but they vary a little from year to year with a 99 being the lowest at 9.7:1 and i don't know any other year cause i have a 99. the turbo 2.2 i believe was 8:1 but not sure and i don't know about the NA 2.2's.

Alot of parts are swap able. From the older turbo 2.2's you can use the headers which ARE turbo headers. or if you are looking for turbo headers buy some off the private for sale forum from a WRX.

What are you trying to do?
-Eli
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Old 04-14-2004, 05:18 PM   #3
squirrelmasta
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Top Mount (TMIC) or Front Mount (FMIC) is all about choice.
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Old 04-14-2004, 05:47 PM   #4
ehlpitel
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i found a real cheap 2.5rs that id wanna turbo, and doing some light esearch, i read somewhere a tmic is inferior to a fmic. I'm hoping the turbo headers from a wrx would fit on a 2.5 rs block, b/c that would be incredibly convinient
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Old 04-14-2004, 05:49 PM   #5
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sorry homez but ur gonna have to read a lot, ive spent over 100 hours reading and still have some questions as i go further and further into my project

alex
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Old 04-14-2004, 05:58 PM   #6
ehlpitel
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would you mind enlightening me...i have a good amount of background info for turbocharging(ive read maximum boost 2 or 3 times) this is something im serious about, and i would greatly appreciate you sharing some knowledge w/ me
thanks in advance
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Old 04-14-2004, 06:03 PM   #7
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TMIC inferior to a FMIC??? well depends i guess. What turbo are you looking to run? if you are looking to stay streetable then you should be able to keep a TM but if you are going crazy then maybe a FM is for you.

Manifolds, yes a WRX manifold will work, but then you need a WRX crossmember for the up/down pipes to work. and a WRX exhaust or a custom exhaust.
-Eli

P.S. Year and a half - 2 years looking at info for a turbo and still don't understand all.
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Old 04-14-2004, 06:17 PM   #8
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word

ur uppipe is going to be fun, i can tell u that now, even a spacer for mine doesnt make it fit, dont buy anything from raykwok that *******, also the xmember isnt a direct swap, get some good washers and use them as shims

also, get about 5 people opinions before you actually do something to your car because lots of people dont know what theyre talking about <no offense to you that do> or like to post info they think is correct but later find out its not
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Old 04-14-2004, 07:39 PM   #9
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i have been told that if you swap the WRX crossmember you also need a WRX front sway bar. i dont know if this is true or not, its just what i have been told. also i have been told that the water pump on the RS engine might have to be replaced with a WRX pump to run wrx headers. i havent checked this one out either.

depending on what 2.5rs you get.. if you get a newer rs (02+) you will need a WRX hood or at least an aftermarket hoodscoop on your hood if you want to use a top mount intercooler. top mount intercoolers are easier to use on the subarus because the throttlebody is so close to the turbo. but front mounts tend to have more surface area and higher airflow through them, which helps cool the charge air more. like was said earlier a TMIC is probably fine for most applications.
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Old 04-14-2004, 08:24 PM   #10
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1-yes it seems ull need a wagon one, still havent purchased one for me
2-yes
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Old 04-14-2004, 10:03 PM   #11
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so, am i better off, getting the header made at a shop? id be doing this on a 98
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Old 04-14-2004, 10:11 PM   #12
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98s had head gasket problems, MAF, and DOHC I belive...

Check out thies threads...

http://forums.nasioc.com/forums/show...hreadid=185230

A wrx swap is easyer and more reilable IMO.

http://forums.nasioc.com/forums/show...hreadid=386462

http://forums.nasioc.com/forums/show...hreadid=518345

www.spdusa.com has some good info too...
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Old 04-14-2004, 10:13 PM   #13
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dont get a header made, ur lookin at like atleast 150 bucks, and get rid of ur engine too get another one, like a 99
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Old 04-14-2004, 10:33 PM   #14
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I think there's no need to get different headers, just the WRX up and downpipes, and the WRX cross member... unless you want to have custom pipes made that will clear your cross member.

And what totoherbs mentioned regarding the headgasket is true. The 98s were known to have a weak headgasket from the factory that will likely eventually blow out as you get up there in miles, and will almost certainly blow out soon if you throw a turbo on. Subaru has improved their gasket design since then, so they simply need to be replaced with newer ones. Many people just turbo anyways, then deal with it after they blow. You can search around and find plenty of info in the normally aspirated forum about blown headgaskets.

j
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Old 04-14-2004, 10:59 PM   #15
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Quote:
Originally posted by ilmaestro
I think there's no need to get different headers, just the WRX up and downpipes, and the WRX cross member... unless you want to have custom pipes made that will clear your cross member.
if you use wrx headers you are going to have to use the wrx crossmember no matter what. a custom up-pipe to miss the stock crossmember would have to be pretty rediculous. and you cant use the wrx uppipe with stock rs header.

you CAN however buy an uppipe that will fit up with a stock rs header. and i would be interested to know if you could then use a wrx downpipe. that might still be useable without changing anything else
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Old 04-15-2004, 12:04 AM   #16
ehlpitel
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is the 2.5 motor thats in the 98 2.5rs the same motor thats ina sti(except n/a)? so ur telling me i need to get a thicker headgasket if i go FI? are u trying to say somehting's wrong with the 98 RS MAF? if so, do i jsut replace it with a newer model one? And by DOHC, do you mean that the 98 is SOHC or DOHC?
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Old 04-15-2004, 12:06 AM   #17
ehlpitel
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all this crossmember, up-pipe, down-pipe bussiness is kinda confusing, would anyone mind elaborating as i dont have good experience w/turbo cars(only read about t in books and from my freinds 740 turbo volvo)? im not trying to swap any engines as i dont have the funds, just want a 2.5rSTI!!
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Old 04-15-2004, 12:08 AM   #18
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Dude start by reading thoes links I gave you.... you have a lot to learn before you should even think about doing something like this.

btw you wont have a 2.5rSTI you will have a turboed 2.5. And you wont be beating, hanging with any STis with it.
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Old 04-15-2004, 12:43 AM   #19
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the STI engine is a boxer engine with 2.5l size... i think thats about the only similarities you are going to get between that motor and the one in the RS

to use WRX up/down pipes on a RS motor you are going to need WRX crossmember/sway bar.

There are turbo kits that are for the RS without changing crossmembers.
http://www.forcedairtech.com/

The turbo in an impreza doesnt mount directly to the exhaust manifold like you have probably seen on the volvo and in books. an up pipe is connected to the end of the header which goes up to a turbo and then there is a downpipe that goes from the turbo back down to the rest of the exhaust.

hopefully that clears up some of your confusion. if not, try asking some more specific questions.
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Old 04-15-2004, 12:46 AM   #20
ehlpitel
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i read the threads, could someone give me some prices of suby engines(some sites would be nice too)? cause if they are cheap like 1 or 2k id consider a swap
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Old 04-15-2004, 12:48 AM   #21
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You got a lot of reading to do. I've been studying this stuff for almost 5 months now and at this point, I still only know about 60% of what I need to get the job done right. Start with the basics... learn how a turbocharger works! Not telling you to search but all the information you need are in these forums. You will gather much more information searching than asking. After you figure out the basics, then answering questions will be much easier for everyone else.

Narrowing your search to only the Aftermarket Forced Induction forums, search for words and phrases like "wrx AND exhaust", "management", "fuel AND parallel", "intake AND piping", "water AND pump". You can learn a lot from those search results.

Also, SubaChad and Jon are your friends.

-Brett
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Old 04-15-2004, 12:52 AM   #22
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Quote:
Originally posted by ehlpitel
i read the threads, could someone give me some prices of suby engines(some sites would be nice too)? cause if they are cheap like 1 or 2k id consider a swap
No, they're nothing like that. An EJ20 swap for instance will end up costing you about $10k or more. If you want to go all out, just get an STi or Legacy short block and built internals. The horsepower potential is much higher and it's about 1/10th the work.

-Brett
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Old 04-15-2004, 12:53 AM   #23
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Quote:
Originally posted by ehlpitel
i read the threads, could someone give me some prices of suby engines(some sites would be nice too)? cause if they are cheap like 1 or 2k id consider a swap
No a working wrx swap is going to be ~$5k... There is nothing cheep about a swap or turboing your car.


You need the piping, turbo, injectors, some way to tune it, install time/money...
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Old 04-15-2004, 12:56 AM   #24
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Quote:
Originally posted by ScoobaruRS
No, they're nothing like that. An EJ20 swap for instance will end up costing you about $10k or more. If you want to go all out, just get an STi or Legacy short block and built internals. The horsepower potential is much higher and it's about 1/10th the work.

-Brett
A wrx swap is cheeper and easy then a sti short block or legacy 2.2 short block. And has greater power potential. With the wrx you get all the parts to turbo it... with the short block you need the ~$2k turbo kit, ~2k stand alone ecu, ~$2k short block, tuning time and installing time... and you still dont have heads worth the cost. Now you can do it over time but you have still spent more money.
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Old 04-15-2004, 12:58 AM   #25
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n0obs represent!
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