These Brave Souls Are K-swapping a Subaru STi

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It takes a lot of ambition to exchange a flat-four cylinder engine from a Subaru with an inline-four and still keep all-wheel drive.

The folks over at BoostedBoiz have kept a certain build a secret, but now that the cat’s out of the bag, it’s time to go forth. They will be taking out a Subaru STi’s flat four motor and swapping in a Honda K-motor, all while keeping the Subaru’s all-wheel drive system.

If you think this is easier said than done, you’re right. That’s why the build will knowingly have some hiccups, but it’ll solve the problem of a string of broken STi motors that prompted the idea of the swap.

Height is going to be the biggest issue to overcome. Without any modifications, the motor does fit front-to-back, but the big issue comes with hood clearance. With a bell-housing adapter already made for the STi’s 6-speed transmission, tilting the engine for extra clearance is out of the question. Instead, a brace that supported the old engine will have to either be modified or removed, but it will at least lower the K block in the Subaru’s engine bay a significant amount.

K-swap Subaru STi AWD

One of the key benefits to this build actually comes from the Subaru itself. Starting with an STi over a WRX means they have a stronger all-wheel drive system to work with, which will most likely be able to handle any power adders they attach to the Honda motor.

As it stands, they still need to figure out the clearance issues, and the clutch before they can start on other components. It’ll be interesting to see how they manage to work with engine management systems in order to have simple things like the tachometer work. Or, perhaps they’ll do a stand alone ECU and all new gauges. As the build moves along, you’ll be sure to hear updates from us.

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Patrick Morgan is an instructor at Chicago's Autobahn Country Club and contributes to a number of Auto sites for Internet Brands, including MB World and 6SpeedOnline.

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