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piston questions.

Discussion in 'Engine Building' started by SkyGuy, Feb 18, 2007.

  1. SkyGuy

    SkyGuy mankind can be stupid.

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    so im looking at pistons to buy and its listing diffrent mm sizes. theres 84.0mm 84.5mm and 85.0mm so im wondering is 84.0mm the stock size and the 84.5mm and 85.0mm is for bored over engines or.....what? i thought when you bored a motor it went by .20 over and .30 over and so on? also if the larger piston mm are the bored over sizes should i send it to a place that bores them by mm? thanks in advance for any help.
     
  2. boostin4fun

    boostin4fun Boosted ls/vtec ohh yeah!

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    The factory bore size depends on what block you have. The b16a, b16b, b18b,b18a, b18c,b18c5 all have factory 81mm size bores. The pistons you are looking at would on work in a b20b or b20z block unless you have one of the other blocks i listed sleeved and bored out. The factory bore size for b20 motors are 84mm. The manufacturer of the piston will list the oversized differently for instance .20 over is .5 a mm, .40 over is 1mm, so on and so on. So if you order pistons .20 over for the b16a for instance it would be a 81.5mm piston. I only recommend going .20 over on any factory block without sleeves. SRP even makes .10 pistons which i am running in my boosted ls/vtec to keep the bores as strong as possible. I hope that clears any confusion up.:)
     
  3. alterdcreations

    alterdcreations Member

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    good info right their
     
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  4. SkyGuy

    SkyGuy mankind can be stupid.

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    so since you listed that the B16 and B18 have a 81.0mm bore size then the b17 would also since its between them? and just to make sure i got this all right the B16, B17, and B18 the only big diffrence between them are diffrent crankshafts to give them more displacment?
     
  5. SkyGuy

    SkyGuy mankind can be stupid.

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    ok well then i guess that makes things easier. so would it b possible to take a B18 crank and put it in my B17 and essentialy make it stroked to a 1.8 litre? or would there be more to it?
     
  6. boostin4fun

    boostin4fun Boosted ls/vtec ohh yeah!

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    It would be worth going to the b18c crank for that little bit of extra torque.
     
  7. tartymctang2357

    tartymctang2357 Grand High Wizard

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    the only other crank that will fit into a b17 block would be a b16 crank, the others would stick out the top of the block by a couple mm, even if you used the b18c crank with b17 rods its still about 3mm above the deck, you could use either a b18a/b or b18c crank with the b17 block if you got custom rods made, and if you notched the block
     
  8. SkyGuy

    SkyGuy mankind can be stupid.

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    thanks for all the great info you guys this will help alot....exept i keep finding pistons that say they are for B16, B17, B18 but they have a bore of 84.0mm...... im lookin on ebay tho.
     
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