Subaru EJ257B – New STi Engine

Look what rolled into Cosworth yesterday: the new Impreza STi EJ257B engine. The new engine in the Ford Focus, sorry, I meant the new Subaru Impreza STi remains mostly unchanged. Although we have not torn it apart yet, externally there are not very many changes aside from some obvious changes and additions. The additions seem to be some smog valves, solenoids, pumps, etc. The changes are here:

The smog/air pump on the top right hand side carries over from the 2007 STi.

Everything here looks almost the same.

Dual AVCS (variable cam angle) should give the engine a broader torque curve. The 2007 engine only had variable intake.

Top feed injectors should make RC Engineering happy again.

The throttle body looks to be the same, but that air control valve for the smog pump stick out like a sore thumb on the left hand side.

That’s about it. I don’t expect the internals to have changed very much. The engine probably still has the weak ass stock pistons and the same crappy connecting rods. I think it will give the STis a good head start in the tuning world compared to the EVO X. Will the EVO X be more rewarding to modify? Perhaps… was in the EVO 9. New engines = new challenges.

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