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3S-GE to 5S-GE

Discussion in '3sge' started by New Guy, Jun 9, 2014.

  1. New Guy

    New Guy Member

    I know what I need to in order to make this swap easy, except for one thing... My GT-S is an automatic, with a very smooth transmission. It's got right around 97k miles on it and shifts like a dream. Unfortunately, the engine is no good. Are the 5S-FE and 3S-GE flex plates the same outside diameter? If not, would I be safe bolting the 3S-GE flex plate to the 5S crank? I've got no problems having the holes closed and new ones drilled if that's what is necessary, but if at all possible I'd like to just use the 5S plate.

    I'd swap in another transmission to make it easy on myself, but the one I have now is a known quantity in amazingly good condition.
  2. spyder

    spyder Well-Known Member

    I was just reading up on this very thing lol. Wish I knew what the benefits was of doing this procedure. As for the transmission, sorry I honestly don't know or I'd help ya out.
  3. New Guy

    New Guy Member

    Okay, went and dug up my pile o' flywheels. The 5S-FE and 8-bolt Gen 1 GE have the same pattern, but the GE flywheel is definitely smaller in diameter. No matter because they are interchangeable.

    The late-model (ST185) flywheel would line up if you used bolts that don't have a shoulder larger than the shank. The holes line up on the inner edge but the 185 equipment is designed around a 10mm shoulder. Grade 9+ bolts would work as a substitute, but a Fidanza would be the better solution.

    The advantage to the 5S-GE is a significant boost to bottom-end torque. The GE head is designed to flow a crapton of air; with a 2.0, that happens at high engine speeds. With a 2.2, the whole torque curve shifts down some as the displacement interacts with the cams differently. It's costly to build a 5S to safely spin fast (forged rods at a minimum, hypereutetic pistons would be ideal, and you should run high-quality ACL bearings) so for now I'm going to stick with another 3S.

    I may in the future build a 5S block for it if I decide to turbocharge it, but that would also require a manual swap as the A140E can not take that kind of abuse... And I've got an All-Trac that will be my go-fast car.

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