Subaru EJ20 Normally Aspirated

Unusually this customer was converting a Subaru EJ20 turbo engine (similar to the one pictured, © Subaru UK Ltd) to normally aspirated induction.

The compression ratio required was 11.0:1, with a bore size of 93.50. The sample piston supplied was a standard EJ20 low compression piston with a flat bowl and two valve relief slots. The finished piston has a raised intruder between the valve reliefs and has the correct volume to achieve a compression ratio of 11.0:1.

In addition to the sample piston, we needed the following information about the customer engine:

  • Bore size
  • Stroke
  • Deck height /clearance
  • Head gasket thickness
  • Cylinder head chamber volume.

The SubaruEJ20 OE low compression piston and the finished forged high compression piston

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