Advice for rebuilding a 2002 WRX
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This is a discussion on Advice for rebuilding a 2002 WRX within the Builds forums, part of the Tech & Modifying & General Repairs category; Hey guys, So to start off I just bought a BRAND NEW (to me) 2002 wrx. The previous owner did ...

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    Question Advice for rebuilding a 2002 WRX

    Hey guys,

    So to start off I just bought a BRAND NEW (to me) 2002 wrx. The previous owner did absolutely no modifications to the car, aside from a sound system, so its 100% stock from the factory! It's a car that i have personally dreamed of owning since ive been about 8 years old and the moment has finally come. The one and only downside to this purchase is that the car has about 170,000 miles on it. I plan on using it as a daily driver so Ive been all over the forums and have gotten the impression that this means I will be in desperate need of another motor here soon. With that said I have decided to take the initiative and plan for the day that I am going to come face to face with an engine rebuild. I have spent hours upon hours researching this motor and how to tear it all the way to splitting the block and replacing the crank. So i am not too afraid of doing a lot of the work myself. I have plenty of quality family mechanics on stand by if I find myself in a bind however.

    Time for the questions...

    1) Should I reuse by current block to rebuild the motor or find one online? And what is the estimated cost of reusing versus replacing? I would like to stick with the 2.0 but am open to suggestions. I have read about a million different threads, but they all use the engine code JDM ej205... is this the same engine that came in the usdm models? If not what is the difference?

    2) would i be able to build the presumed ej205 to the same specs and the ej207? which i've read is more powerful and reliable, but i also dont know if this is total fact. If I can rebuild the 205 to match the 207 what would I need to do to it?

    3) I'm really not looking for anything more than like around 300 horse power because I would like to avoid having to replace the trans if I can help it. With that said, what components should I build the motor with to hit that power mark but still retain good reliability, since it will be my daily driver?

    4) does any one have good suggestions as to where I can find a good short block for a decent price? I am considering the option of buying a second engine to put on a stand in my garage. That way I can build this engine over the next few months, with aftermarket parts. then when this one fails I will already have one ready to drop in so I dont have to go without a vehicle for an extended period of time. Everywhere I look I find only long blocks. Do i have to resort to junkyard hunting? I know that buying a used short block usually will mean I have to get the engine rebored. exactly what goes into doing this from my end aside from taking it to a machine shop?... speaking of reboring, does anyone have a price estimate as to what that usually costs? can pretty much any used block be rebored and used again? if not what kind of damage causes an engine block to become nothing more than a boat anchor.

    Thats all the questions I have for now. I know that I am asking for a lot here and I truly appreciated everones input. like i said, this is my first subie and owning it is a dream come true so I would like to do it right. Im an engineering student at asu and the engineer in me just wants things to be as perfect as possible.

    Thanks for all of your help and I look forward to speaking with you all.

    Ashby out.

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    Super Moderator (Actually a SuperSpy) SD_GR's Avatar
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    What is wrong with your motor? Sorry I don't follow.
    The world breaks everyone and afterward many are strong in the broken places. But those that will not break it kills. It kills the very good and the very gentle and the very brave impartially. If you are none of these you can be sure it will kill you too but there will be no special hurry. Ernest Hemingway, A Farewell to Arms, 1929
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    I believe his current motor is ok right now, but he's just trying to gather information about what to do if/when it blows up. OP if you're concerned with the health of your current motor start by doing a compression and leakdown test. If these numbers are good, odds are you're in decent shape. Then I would look at things like timing belt (Depending on when the previous owner did one) as well as other wear items (Like hoses,bushings, new gaskets etc.). Maybe even order a rebuild kit for your turbo. Also send an oil sample to be analyzed. I would do those things first to try and prevent having to rebuil/buy a new motor. IF all those things check out then you could start looking at modding, but again your motor does have 170k on it at this point, so even if everything checks out you could do something as simple as a reflash and blow your motor. I can say that if you're looking for 300whp in your wrx you would need full bolt ons as well as a bigger snail and all supporting fueling mods. Either way congrats on your new to you wrx and welcome to the club!

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    Super Moderator (Actually a SuperSpy) SD_GR's Avatar
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    I'd wait until something goes wrong. It should be years.
    The world breaks everyone and afterward many are strong in the broken places. But those that will not break it kills. It kills the very good and the very gentle and the very brave impartially. If you are none of these you can be sure it will kill you too but there will be no special hurry. Ernest Hemingway, A Farewell to Arms, 1929
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    DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.

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    Quote Originally Posted by WVRex2010 View Post
    I believe his current motor is ok right now, but he's just trying to gather information about what to do if/when it blows up. OP if you're concerned with the health of your current motor start by doing a compression and leakdown test. If these numbers are good, odds are you're in decent shape. Then I would look at things like timing belt (Depending on when the previous owner did one) as well as other wear items (Like hoses,bushings, new gaskets etc.). Maybe even order a rebuild kit for your turbo. Also send an oil sample to be analyzed. I would do those things first to try and prevent having to rebuil/buy a new motor. IF all those things check out then you could start looking at modding, but again your motor does have 170k on it at this point, so even if everything checks out you could do something as simple as a reflash and blow your motor. I can say that if you're looking for 300whp in your wrx you would need full bolt ons as well as a bigger snail and all supporting fueling mods. Either way congrats on your new to you wrx and welcome to the club!


    Sounds good! I will definitely do those tests right away! I know the compression is supposed to be around 8:1 but what else will I be looking for with the other tests? I think I will avoid modding the current engine because I'm terrified of the possible results.. And 20 hp gains with a reflash doesn't sound worth blowing my motor.

    Aside from keeping my current engine alive, do you have any input for the said questions above? I know that it's kinda sac religious to count a perfectly good engine dead but I know that this isn't a Honda or Toyota, both of which are previous cars I have owned, which means that it's really only a matter of time before something fails. And when it does i would really like to be prepared for it, because it will be my daily and I won't be able to go without a car for long.

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    He doesn't mean the compression ratio of the engine. He means checking the compression of each cylinder. Each cylinder should be above 120 and within 5-10 of each other. So say you get a compression check done and it looks something like this:

    Cylinder 1 - 135
    Cylinder 2 - 140
    Cylinder 3 - 135
    Cylinder 4 - 140

    That would be a good compression ratio and indicate an otherwise healthy engine.

    Now if the numbers are similar to these then you may have a problem and need to really start considering a rebuild/new motor.

    Cylinder 1 - 135
    Cylinder 2 - 140
    Cylinder 3 - 140
    Cylinder 4 - 105

    That would indicate that you are losing compression in Cylinder 4 and have a problem.
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    Oh that makes sense! I forgot that compression ratio depends on how far the piston moves up in the cylinder, not the amount of compression the cylinder produces.. Do you guys have any tips on performing a compression test? I've read that people have issues with getting the tester screwed into the spark plug hole. And is it safe to just unscrew the tester immediately after checking the cylinder? Or will there be a lot of pressure that's gonna blow my hand off? Also will pulling the ignition fuse also remove power to the fuel pump or do I need to pull that fuse too?

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