Engine advice needed
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This is a discussion on Engine advice needed within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; Hey guys i'm new to the subaru world and need some advice on which is the best route to go. ...

  1. #1
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    Engine advice needed

    Hey guys i'm new to the subaru world and need some advice on which is the best route to go. I have a 03 WRX that needs a motor rebuild. I have been searching different forums for info and have come up with a few options but need to make a decision on which would be the best route to go. Whichever route I take, I will go with forged internals to handle my power goals down the road.

    Option #1 rebuild 2.0 with good rods/pistons arp head studs etc.
    Option #2 2.2 closed deck shortblock with forged internals, still not 100% positive what all I would have to modify to make this work in my car
    Option #3 2.5 hybrid with forged internals and 2.0 heads, if I go this route I know I want a closed deck block but not sure which cars are the ones to look for a donor block from
    Option #4 go with a 2.5 STI engine and upgrade the pistons.

    Out of the options listed what would be the most reliable and cost effective route to go? The reason the 2.2 is listed is I found a 2.2 turbo motor here locally that already has forged internals but has a spun rod bearing for $900 that is a little cheaper than buying the 2.0 forged rods/pistons and I would be doing the same machine work to that motor as I would to the stock 2.0. Any info is greatly appreciated.

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  3. #2
    zax
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    I'd go with option #5 rebuild the 2L case with STi crank, rods, and forged pistons; case bored 50 thousandths over i.e. 2.1L stroker


    But it's really up to you

    Quote Originally Posted by scubynewby View Post
    Option #1 rebuild 2.0 with good rods/pistons arp head studs etc..
    Not worth it IMO. The 2.0L just won't perform to the level of a motor with a longer stroke.

    Quote Originally Posted by scubynewby View Post
    Option #2 2.2 closed deck shortblock with forged internals, still not 100% positive what all I would have to modify to make this work in my car.
    2.2L motor... tough to find, not as many build options... furthermore, the 2.2L displacement was achieved by boring out a 2L block, so the lag will be as bad as a 2.0L. Personally, not my favorite build.

    Quote Originally Posted by scubynewby View Post
    Option #3 2.5 hybrid with forged internals and 2.0 heads, if I go this route I know I want a closed deck block but not sure which cars are the ones to look for a donor block from
    2.5L hybrid is the most common build. If you want longevity, you really need to have your heads machined to volume match the block (and achieve the desired CR). Stay away from the thicker headgaskets, as unmachined heads will upset the quench area of the compressed piston. 2.5L is not offered in a "closed deck" arrangement per my understanding. EJ255/257 blocks are "semi-closed" meaning that the cylinders are supported by a small amount of aluminum on either side of the cylinder. However, don't base your build off of a closed/open deck arrangement: EJ205 cyl walls are plenty thick to support significant boost pressure with proper head studs and the EJ257/255 blocks (despite a thinner cyl wall) are equally strong. A test mule on the LGT forums was running an EJ205 at 35 PSI for 10k miles with proper head studs and found nominal ovaling of the cylinder. Your choice between a Hybrid build and a 2.1L should be entirely based on preference.

    Quote Originally Posted by scubynewby View Post
    Option #4 go with a 2.5 STI engine and upgrade the pistons.
    This will require serious effort. You will require either a new ECU and harness or (if the stock ECU is retained) you may use the EJ205 throttle body and plugs for the AVCS oil feed/return lines. If you are rebuilding the motor (as you have stated here), I'd consider a Hybrid long before a full swap... Hybrids will make more torque anyhow.
    Last edited by zax; 03-20-2013 at 08:18 AM.
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    It's not up to any of us, really. You have to decide what works best for you, but if I were to do it it would be option #3. Do some bowl and port work to those 2.0L heads, a valve job, and while you're at it throw some 272 cams at it from whatever company you see fit, and drive a torque monster.

    That would probably open up a pandora's box though, cause after that, if you plan on gettin' after it regularly, you'd most likely have to at the least put an RA gearset in the trans.....

    Good luck.
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    Thanks for the input guys I was leaning toward the 2.5L Hybrid but am now intrigued by the 2.1L idea


    [QUOTE=zax;2996623]I'd go with option #5 rebuild the 2L case with STi crank, rods, and forged pistons; case bored 50 thousandths over i.e. 2.1L stroker

    When you say STI crank/rods pistons are you talking the 2.5L sti parts? If not what parts do I need to look for on this?

  6. #5
    Subaru Newb MainFrame's Avatar
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    There is no closed deck 2.5L block, don't know why you would want closed deck anyways. ej257 blocks are semi-closed, which is plenty strong, and doesn't have the overheating issues associated with a fully closed deck block.


    I'd do the 2.5L hybrid.. rebuilding the 2L is kinda pointless unless you're not concerned about performance and just want to save money. Your option #4 would be a huge waste of time and money in my opinion.

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