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Thread: 2.5I motor?

  1. Top Of Page | #1
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    Question 2.5I motor?

    Been doing some research but I want current info.

    How is the 2.5I motor in the 06-07 impreza?


    I've been thinking about joining my GF and the rest of the Subaru crew, and replace my Ford focus wagon with one.

    Now the reason I'm thinking 2.5I is, because I'd like to get one between the years of 06-07 so it's a hawkeye. And for some reason, it seems WRX hawkeye's are rare around CT.

    So what types of problem do these motor's pose, and could they take a VF39 turbo on stock internals? And can the 5 speed trans handle power/launches, or are they still considered the glass trans, even in these newer models.

    FYI: My GF's is a 04 WRX 5 speed

    Thanks guys, hope to join the crew soon, and have two Subaru's in the garage.

    Dave

  2. Top Of Page | #2
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    The 06/07 Impreza 2.5i has a 2.5 motor that is called an EJ251. It is the second design 2.5 designed by Subaru. The block is much stronger, the journals are larger, the rods are larger, and the thrust bearing was moved. And as designed, it is less likely to have the leaking head gasket and bearing issues associated with the Phase 1 EJ25D.

    You can not turbo this motor over about 6/7 PSI. It is not designed to handle boost. It's of the open deck design. This means that the coolant passageways are larger and the cylinder walls are thinner. These motor are best build for high compression. Replacing the head gaskets with Cometic 0.027" gaskets (OE is 0.030") will raise the compression to about 11.5:1, which will give you more bottom end power and a bit more overall power. Beyond that, I would not go crazy. big money HC builds have not been known to be the most reliable. So upgrading the bottom end is a waste of time. Thinner gaskets, some cams, headers, and a high flow exhaust are the way to go with the 251. It's the best bang for the buck.

    As far as the trans is concerned, I don't know much about the 5MT after 1999. I don't even know if they changed the internal design. I know gearing is mostly the same, depending on the model. And I know that they use the same final gear ratios. Upgrading the clutch to an Exedy KSB04 will allow you do to all the hard launches you want. That clutch is rated to handle at least the power of the 250 horse power H6 motors.

    I am think about buying an 07 2.5i that I found. 5MT and all. Welcome to the forum, and I hope you end up with a Subie in the end!

  3. Top Of Page | #3
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    Thanks man, knowing it's not a good candidate for a turbo build as is...... Makes me think I'll join my GF, and park two blobeye's in the drive way.

    Cause besides the trans being glass, and not allowing hard launch's without serous repercussions, I thinks it's a great motor with higher success rates for a good reliable turbo build up.

    In all my goals aren't crazy, 310-350HP would be nice.
    Last edited by DjWRX; 02-10-2013 at 12:56 PM.

  4. Top Of Page | #4
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    for gas mpg 2.5, for decent get and go and well mpg 2 WRX. All the bells and whistles STi +protune. But all in all man you're gonna get the MOD FLU and its a persistent bug let me tell u.

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