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Old 09-22-2008, 05:32 PM   #1
JLW2007RS
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Default 2.5i turbo Q's Not swapping not trading in

2007 2.5i 16,500 miles

I have posted a number of times about different options etc. I have looked into turbo charging and haven't gotten any straight and knowledgeable answers. The one answer i have gotten over and over again is. "sell it and get a wrx" I DON'T WANT TO.

I have looked into getting a short block and building it up, but the responses i have gotten from that weren't good either. Still i got the, "sell it and get a wrx." Thats not what I'm looking for. I know it's not easy, I know it's not cheap or worth it. But god damnit i want it.

This is my proposition, can somebody tell me if its safe, if its not what i'm gonna need to do to get it safe. Im not looking for monster gains. I would be happy with 50 horsepower.

-I would like to install a stock WRX turbo system on my engine. I am not looking to boost any higher than 5 psi. I am aware that i have 10:1 and that i have SOHC. I am ready to put header back exhaust, FMIC or TMIC on the car. And if i need to put larger injectors on the engine so be it.

What i want to know is your input. Please knowledgeable descriptions and parts descriptions.

Thank you in advance for your help. It is very much appreciated\

Also, i have read the thread about the 2002 RS and have that information in mind.
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Old 09-22-2008, 05:46 PM   #2
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i believe you would have to get some sort of aftermarket engine management system.
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Old 09-22-2008, 07:42 PM   #3
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It's "safe" but it won't be reliable. There are more and more guys that have done the turbocharging thing that have later gone on to swap and immediately regretted doing the turbo kit in the first place. There's a reason why people say "swap" or "sell it and buy a WRX" - it's more reliable and will cost you less in the long run.

Regardless of that, I have gone the aftermarket forced induction route in the past (and later swapped, but that's irrelevant) and posted a huge write-up here. Search for it, it's around.

If you have any more specific questions, ask away but just a "give me feedback on my idea" or "give me some input" is too general and in order to help you, we need to find out what you know and what you don't know. From there, you can be helped.
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Old 09-22-2008, 07:45 PM   #4
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define reliable please? silentt thank you for your input
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Old 09-22-2008, 08:45 PM   #5
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define reliable please? silentt thank you for your input
It's reliable to the point of you worrying something is going to go wrong whenever you drive the car.
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Old 09-22-2008, 09:40 PM   #6
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i was also in the route of doing a small turbo upgrade on my 06 2.5i, but from what i understand, the engine internals would not be strong enough.
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Old 09-22-2008, 10:12 PM   #7
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Quote:
Originally Posted by thethaddeus View Post
i was also in the route of doing a small turbo upgrade on my 06 2.5i, but from what i understand, the engine internals would not be strong enough.
Internals can handle up to 5-6psi of boost.
Gains to cost comparison is highly negligible, and yes, there would seem to be reliability issues.

Keep in mind besides the turbo build you will need:
New exhaust, turboback
WRX crossmember I believe
ECU
A tune
New Clutch
New tranny
Labor costs
Brake upgrades possibly
etc. etc.
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Old 09-23-2008, 09:15 AM   #8
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Old 09-23-2008, 10:33 AM   #9
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Everyone is just trying to rain on your parade. You could buy a turbo kit from avo or FAT and chances are you'd be perfectly fine. If you got a pro tune, you'd be even more reliable. But just cuz someone makes a smart ass comment doesnt mean they're right.
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Old 09-23-2008, 01:01 PM   #10
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Everyone is just trying to rain on your parade. You could buy a turbo kit from avo or FAT and chances are you'd be perfectly fine. If you got a pro tune, you'd be even more reliable. But just cuz someone makes a smart ass comment doesnt mean they're right.
When did you finish your turbo kit?

I am speaking from experience. What would you trust more, a huge team of world-class engineers that designed a car around certain criteria or some dude that decides to "slap" a turbo in his car? I went the turbo route, later went swap route. I know which I prefer.
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Old 09-23-2008, 03:28 PM   #11
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Well since i am studying to be an engineer i would go with the engineers. However you must realize that the motor was not turbo charged because they wanted a very fuel efficient vehicle, not because it was unreliable.

Everyone knows you can't throw 15psi at it and expect it to hold. But 5 psi is safe, and will hold for a good chunk of time. Obviously you don't have the potential to go bigger and better, which is why everyone puts down the N/A turbo charged motor, but it is safe.

The engineers who designed the turbo kits that would be "slapped on" did it so that it was safe. So im gonna trust the world-class engineers.
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Old 09-23-2008, 09:07 PM   #12
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Originally Posted by Chocoholic005 View Post
Well since i am studying to be an engineer i would go with the engineers. However you must realize that the motor was not turbo charged because they wanted a very fuel efficient vehicle, not because it was unreliable.

Everyone knows you can't throw 15psi at it and expect it to hold. But 5 psi is safe, and will hold for a good chunk of time. Obviously you don't have the potential to go bigger and better, which is why everyone puts down the N/A turbo charged motor, but it is safe.

The engineers who designed the turbo kits that would be "slapped on" did it so that it was safe. So im gonna trust the world-class engineers.

Are you seriously comparing the turbo-kit builders over Subaru?

I have turboed an N/A car and it is not something you can do reliably for the long run. You will run into problems and it will not be fun unless you like tinkering with your car a lot. I would not do this to a daily driver. The Subaru ECU will not like the things you need to do with it. If you want a turbo then make the proper sacrifices and sell it or swap it. These sacrifices will be more at the beginning but much less in the long run.
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Old 09-23-2008, 09:23 PM   #13
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turbocharging your NA is possible, but it is not cheap. Here's a thread to look at: http://www.rs25.com/forums/showthread.php?t=72808

Last edited by silentt; 09-23-2008 at 11:17 PM. Reason: getting back on topic
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Old 09-23-2008, 09:55 PM   #14
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I applaud you for studying engineering, maybe when you get further along you'll understand this whole concept a bit more. Judging by your posts so far I would assume you're either a first year or just entering your second. I'm well aware that the NA motor was designed for fuel efficiency, but what increases fuel efficiency? That's right, COMPRESSION! They built the NA motor with higher compression since if they just used an STI block/heads/etc without a turbo, the car would have terrible mileage and very little power.

You have to ask yourself, why did these engineers use lower compression in their boosted engines? There are a few main reasons for this but the most important one is reliability. You can't expect to have fantastic reliability on a high compression engine running a turbo. You get a bad batch of gas, the tune isn't 100% perfect, or some other factor and you're looking at a blown engine. Ask most tuners how good the factory maps are. They'll tell you that the stock maps aren't very good at all.

There's a reason engineers designed the turbo engine to have low compression and there's a reason they designed the naturally aspirated engine to have high compression.


Is a "good chunk of time" long enough for you? How do you know when the "good chunk of time" is up? You don't, all you can do is sit and wait for your engine to grenade.


For the most part, it's not the engineers that designed the turbo kits. Many tuner shops and automotive places are designing the turbo kits, not automotive engineers. You have to realize that the guys that work at Subaru, Ford, GM, etc. are not just any engineers. They are the cream of the crop, not just guys that had good enough grades to graduate.
1. You missed my whole point. I was not talking about compression. Yes it makes better gas milage. I was saying a they didnt put a turbo on the 2.5i because they were aiming for the best gas milage. Not because the motor would be unreliable with one. Yes because of the higher compression it would be less reliable, but a small ammount of boost would have been up to standards.

2. Every engine will not last forever. Nooone knows how long. I would say 50k plus for most engines with a bolt on kit.

3. In the big companies its engineers. FSU is the best automotive engineering college in the country. We have students working for Greddy, Apexi, Ford, Dodge, all the GM branches, Toyota, Nissian, Mitsubishi, Castrol, JBL, the list goes on... all in the R&D programs. We might even have someone working for AVO, but dont quote me on that one. I know how the job placement thing works.
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Old 09-23-2008, 10:04 PM   #15
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Your point is good no doubt but based on actual people who have done it and still have it in there car what would you say to that...a bad piece of gas can happen to anyones turbo'd car thats why its good to throw in 2 bottles of a well trusted octane booster company such as NOS,TORCO racing,or VP racing fuels.. in even an STI...the kit is very relaible and its those people that throw on a turbo change oil at 5,000 miles instead of 1,000 miles and such forth that suffer in the end....also if you really feel any way about it theres always installing thicker head gaskets for an already very relaible 6psi kit. Talked to the guys at RalliTek about this..I also threw alot of debated questions at them from this site and they still agree that its a well created kit that works at the setting that it was intended for...plus water cooled and oiled how many turbo's now days are even still water cooled lol.Either way I have a motor that has 9,000 miles on my 06 that I just ordered TENZO-R rims and Megan racing coils..the AVO kit is next...then in the end an STI or WRX block..just to be able to turn up the boost anyways. The kit works fine as long as you follow turbo powered vehicle procedures...blow-off valve and turbo timer..no boost controller till intenal upgrades...but you make it seem like the engine is crap..and its not..further more if you really feel anyway about it just order some forged pistons because there the same on the 2.5i aswell as the wrx 99.5mm. Which will bring down compression to 8.5 perfect for say 10 pounds...but better kept at 6 or 8 mainly for open block reasons or just order a sti or wrx block..with the SOHC heads which flow better than the DOHC heads anyways...theres lots of routes you can take and all will work just fine with research...but sure swapping a motor from say the N/A motor is gona be better only because you can run more boost not because its wrong. Either way like someone else said don't let yourself get bashed by people and make up your idea not to do it..I'm gona do it cause i want boost then a block switch after I've had some boost to get more boost. Done deal.
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Old 09-23-2008, 10:23 PM   #16
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Quote:
2. Every engine will not last forever. Nooone knows how long. I would say 50k plus for most engines with a bolt on kit.
How do you figure that? Do you have actual data or are you just guessing? That 50k is tiny compared to the low boost setup in the ej22t legacy. There are many of those cars around with over 350,000kms (over 200k miles) all on original engines.

Last edited by silentt; 09-23-2008 at 11:21 PM.
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Old 09-23-2008, 10:55 PM   #17
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How do you figure that? Do you have actual data or are you just guessing? That 50k is tiny compared to the low boost setup in the ej22t legacy. There are many of those cars around with over 350,000kms (over 200k miles) all on original engines.
Just based on others with the kits, talking to Fat, that kinda thing.
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Old 09-23-2008, 10:59 PM   #18
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Just based on others with the kits, talking to Fat, that kinda thing.
Ah, so no actual experience. Gotcha.
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Old 09-23-2008, 11:06 PM   #19
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Yeah that is his specialty
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