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Thread: Proper Cam Specs for Phase 1 DOHC.

  1. #1
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    Proper Cam Specs for Phase 1 DOHC.

    Being that I said SL-i would be the ONLY place to find data, I will hold true to that and insert one of my emails here. It is a collection of cam data an old friend gave me from about 5yrs ago from work we did on a few Phase 1 engines we had in the past.

    There are also differences between the late model heads, MANY, which will be too much to dig into at this time. For now, let's focus on the cam specs so people know what they're dealing with when they run into them. Please note that the early 20G STi, 1996 25D (not on here yet), EJ20H 8.5:1, and 20D heads are of the older "4CAM 16VALVE" type and are not compatible with the later K/R/D/H/G type.

    Late USDM EJ25D:
    Intake opens 6° BDTC.
    Intake closes 50° ABDC.
    Exhaust opens 54°/30° BBDC.
    Exhaust closes 10°/10° ATDC.
    Overlap 16°.
    Intake/Exhaust lift 7.6mm/7.4mm.

    Late JDM EJ20G/H:
    Intake opens 8° BDTC.
    Intake closes 52° ABDC.
    Exhaust opens 52° BBDC.
    Exhaust closes 8° ATDC.
    Overlap 16°.
    Intake/Exhaust lift 8.1mm.

    Late JDM EJ20K/R STi:
    Intake opens 10° BDTC
    Intake closes 56° ABDC
    Exhaust opens 56° BBDC
    Exhaust closes 12° ATDC
    Overlap 22°
    Intake/Exhaust lift 8.2mm/8.3mm.

    Early JDM EJ20H 8.5:1:
    Intake opens 10° BDTC.
    Intake closes 50° ABDC.
    Exhaust opens 58° BBDC.
    Exhaust closes 2° ATDC.
    Overlap 12°.
    Intake/Exhaust lift 7.6mm.

    Early JDM EJ20G STi:
    Intake opens 6° BDTC.
    Intake closes 56° ABDC.
    Exhaust opens 55° BBDC.
    Exhaust closes 11° ATDC.
    Overlap 17°.
    Intake/Exhaust lift 8mm.

    Early JDM EJ20G:
    Intake opens 2° BDTC.
    Intake closes 50° ABDC.
    Exhaust opens 46° BBDC.
    Exhaust closes 10° ATDC.
    Overlap 12°.
    Intake/Exhaust lift 7.5mm.

    Early Euro EJ20G:
    Intake opens 2° BDTC.
    Intake closes 48° ABDC.
    Exhaust opens 51° BBDC.
    Exhaust closes 5° ATDC.
    Overlap 7°.
    Intake/Exhaust lift 7.5mm.

    Early JDM EJ20D Cam Specs.
    Intake opens 6°/4° BDTC
    Intake closes 54°/56° ABDC
    Exhaust opens 66°/36° BBDC
    Exhaust closes 24°/16° ATDC
    Overlap 30°/20°
    Intake/Exhaust lift 8.5mm/7.5mm?

    Try as I might, I can't find the proper lift specs for the 20D, so if anyone wants to insert that data, feel free. The specs are legitimate for the other cams, though. As you all can see, the 20K cams are the hottest to have ever been produced by Subaru in all the years of its Phase 1 EJ camshaft production.

    The 20D cams interest me, as they seem to be the wildest in the N/A department. It would be cool to see them at work on a 2.2L or 2.5L block. (I request that this become a sticky.) You may notice that there are no "non-STi EJ20K" pair of cams. This is because the late EJ20K and late EJ20G are EXACTLY the same.
    Last edited by Alucard; 08-28-2023 at 01:27 PM.

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