Building the FR-S FA20 Engine with Stay Crushing, Assembling the Engine!


The flex hone will not change the bore’s dimensions, which is critical in any Subaru engine due to the distortion of the block when being assembled. Any machine work that alters the bore dimensions must be done with the proper fixturing.


Because the flat engine configuration does not allow a socket wrench to have a straight shot at the rod main caps, the Brian Crower rods have offset main caps. Here, Howard torques them down.

Our Supertech filled, Portflow Design cylinder heads were assembled and bolted to our engine cases.   To torque the heads down, the camshafts have to be removed.

Next, Howard installed the camshafts, roller rockers, and rocker pivots.  The valve lash is adjusted by select fit caps over the valve stems.

The direct injection common rail, injectors, and high-pressure fuel pump were installed, along with the variable timing sprockets and timing chain.

Howard put the flywheel bolts into the crank a little bit so they would not get misplaced.

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