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Thread: Using 2.2 pistons with 2.4 crank & rods ?

  1. #1

    Using 2.2 pistons with 2.4 crank & rods ?

    Guys
    Decided to change to 2.4 crank & rods but already have the 2.2 pistons …
    Pistons are CP 87.5x9.5x 2.2r (66stroke)
    Cylinders are LN 87.5

    Was advised that the piston skirts need trimmed by +- 1mm to clear at crank ?
    Also will the 2.4 rods mount to the 2.2 pistons or mods needed ?

    Thanks for comments & recommendations
    Frank
    73.5 Snrf T
    71 Snrf T
    70S targa
    76 914 2.0
    82 Targa,
    85 Alfa GTV6
    60 Lancia Appia Zagato GTE
    Searching for transmission 7115322 (911/01)

  2. #2
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    with cylinders at 87.5 from LN ; I assume you had to enlarge the spigots on the case for those cylinders right?
    1. Chris-Early S Registry#205
    2. '70 911S Tangerine
    3. '68 911L Euro Ossi Blue

  3. #3
    Yes spigots were enlarged….
    Any thoughts on the 2.2 pistons mounting to the 2.4 rods ?
    Seems the CR will be over 10 …shooting for around 9.5 what’s recommended?
    Thanks
    Frank
    73.5 Snrf T
    71 Snrf T
    70S targa
    76 914 2.0
    82 Targa,
    85 Alfa GTV6
    60 Lancia Appia Zagato GTE
    Searching for transmission 7115322 (911/01)

  4. #4
    Quote Originally Posted by raspy2point2 View Post
    with cylinders at 87.5 from LN ; I assume you had to enlarge the spigots on the case for those cylinders right?
    Please correct me if I am wrong, but aren't the 87.5 LN Nickies the largest LN cylinder that will sleep fit the stock 2.2 case spigots? It was my thought that the spigots did not need to be enlarged?

    Thanks!

  5. #5
    Senior Member teenchy's Avatar
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    Quote Originally Posted by Alaskan911 View Post
    Please correct me if I am wrong, but aren't the 87.5 LN Nickies the largest LN cylinder that will sleep fit the stock 2.2 case spigots? It was my thought that the spigots did not need to be enlarged?
    That was my understanding per LN and the reason why I went with them for my build (87.5 x 66 = 2380cc).
    (a) 1970 911T Sportomatic coupe
    (b) 2016 E350 4MATIC wagon; parts hauler for (a)
    ESR #1474

  6. #6
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    And so do they fit teenchy? My understanding is the largest without enlarging the spigots is 86 mm. and that is pushing it. You end up with very thin cylinder walls and risk warping the walls.
    1. Chris-Early S Registry#205
    2. '70 911S Tangerine
    3. '68 911L Euro Ossi Blue

  7. #7
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    Everything will work just fine with a small corner taken off of the piston at the bottom corners on the skirt. I built a 2.4 engine using this combo a few years ago and I test fitted the rod with a piston on the crank outside of the case. You will see where the piston hits on the crank throws. Grind to get the desired clearance. Then rebalance everything.

    If you want to lower the CR just add some shims under the cylinders.

    Good luck with the build. It's a great combination that works really well.

  8. #8
    Senior Member teenchy's Avatar
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    Quote Originally Posted by raspy2point2 View Post
    And so do they fit teenchy? My understanding is the largest without enlarging the spigots is 86 mm. and that is pushing it. You end up with very thin cylinder walls and risk warping the walls.

    Yes. The case only required a line bore in addition to the oil bypass and piston squirter mods (it's a '70T case).

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    (a) 1970 911T Sportomatic coupe
    (b) 2016 E350 4MATIC wagon; parts hauler for (a)
    ESR #1474

  9. #9
    After much going back and forth on pistons and understanding they will work
    have decided to Go with 2.4 piston
    So have decided to sell the 2.2 (66 stroke ) pistons
    These are for a 2.5 engine build
    They are listed in for sale section paid $1200 posted at $850

    Thanks for all the info related to the build
    Frank
    73.5 Snrf T
    71 Snrf T
    70S targa
    76 914 2.0
    82 Targa,
    85 Alfa GTV6
    60 Lancia Appia Zagato GTE
    Searching for transmission 7115322 (911/01)

  10. #10
    The pistons are sold
    Thanks
    Frank
    73.5 Snrf T
    71 Snrf T
    70S targa
    76 914 2.0
    82 Targa,
    85 Alfa GTV6
    60 Lancia Appia Zagato GTE
    Searching for transmission 7115322 (911/01)

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