noob Q concerning 2.5/STi engines
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noob Q concerning 2.5/STi engines
just out of curiosity, does the 2.5 RS share the same engine block as the STi and Legacy GT? if so, couldn't you swap the head/turbo/etc. from the legacy or sti onto the rs? i'm new to the subie world, i currently drive a honda, a ton of honda engines have interchangable parts.
i'm deciding between getting an RS or forking out the extra 5k for a WRX.
i'm deciding between getting an RS or forking out the extra 5k for a WRX.
Dirty Redhead
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Joined: Sep 2004
Posts: 7,204
From: Commuting? I don't know what that means anymore.
Car Info: 05 WRX Wagon (Crystal Gray)
The engine block is slightly different and the EJ251 (the 2.5RS motor) is weaker. It has less cylinder wall reinforcement.
https://www.i-club.com/forums/engine-power-ej25t-sti-2006-wrx-90/closed-deck-vs-semi-closed-82752/
For pictures of the short block with the heads off. The first picture is of the 2.5RS engine. The second one is a closed deck engine (not in any current model subaru, but older ones) and the third picture is from the STi motor.
The EJ251 motor can be turbo'd but not easily, nor relatively safely.
https://www.i-club.com/forums/engine-power-ej25t-sti-2006-wrx-90/closed-deck-vs-semi-closed-82752/
For pictures of the short block with the heads off. The first picture is of the 2.5RS engine. The second one is a closed deck engine (not in any current model subaru, but older ones) and the third picture is from the STi motor.
The EJ251 motor can be turbo'd but not easily, nor relatively safely.
Dirty Redhead
iTrader: (10)
Joined: Sep 2004
Posts: 7,204
From: Commuting? I don't know what that means anymore.
Car Info: 05 WRX Wagon (Crystal Gray)
Originally Posted by sonicsuby
Eric has teh rawk.
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thanks for the info. good stuff. does the RS respond well to modifications (n/a mods)? my current car hates modifications, it doesn't do well at all with aftermarket goodies, damn 7th gen civics. if i keep the RS n/a and do I/H/E and some other bolt on goodies, what kind of turnout could i expect? i already know the WRX loves mods, so i'm hoping the RS has some kind of decent ability. i really like the AWD feature of the subies, but i am on a budget. i love the look of the newest imprezas, 04+. i test drove a wrx, and it hauls, it reminds me of my old 2000 mustang gt, but i think it pulls even harder at some points (from the turbo no doubt). thanks again for your input everyone.
Registered User
Joined: Apr 2003
Posts: 170
From: SoCal
Car Info: 2.5RS STI swapped
Well I think it's mostly opinion... I'd get the RS. Especially with the name AutoX. The RS can spank in autocross. Crazy torque on the 2.5 RS's. They're geared lower also. I can keep up with a corvette... well for the first 40-50 feet 
Anyway yeah for autocross the RS is a pretty strong competitor. With I/H/E you can get some pretty good gains. Prolly looking at an adititional 20HP. That doesn't nessicarilly mean you'll go from 165 to 180peak hp mind you. But you'll feel it and enjoyment will be had for sure. I think I might be going all motor. I've been told that you CAN reach 250HP and still be pretty reliable. We'll see how that goes. But start with suspension on the 2.5RS and you'll have a blast at the autox.
cheers
garrett
Anyway yeah for autocross the RS is a pretty strong competitor. With I/H/E you can get some pretty good gains. Prolly looking at an adititional 20HP. That doesn't nessicarilly mean you'll go from 165 to 180peak hp mind you. But you'll feel it and enjoyment will be had for sure. I think I might be going all motor. I've been told that you CAN reach 250HP and still be pretty reliable. We'll see how that goes. But start with suspension on the 2.5RS and you'll have a blast at the autox.cheers
garrett
Originally Posted by AutoX
thanks for the info. good stuff. does the RS respond well to modifications (n/a mods)? my current car hates modifications, it doesn't do well at all with aftermarket goodies, damn 7th gen civics. if i keep the RS n/a and do I/H/E and some other bolt on goodies, what kind of turnout could i expect? i already know the WRX loves mods, so i'm hoping the RS has some kind of decent ability. i really like the AWD feature of the subies, but i am on a budget. i love the look of the newest imprezas, 04+. i test drove a wrx, and it hauls, it reminds me of my old 2000 mustang gt, but i think it pulls even harder at some points (from the turbo no doubt). thanks again for your input everyone.
Yeah, moderately modded RSs can easily keep up with stock (or slightly modified) WRXs on the AutoX course no problem (well, depending on drivers). I've seen RSs with I/H/E put down ~135hp on mustang dynos (which dyno stock somewhere between 110hp and 115hp)
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