'Porting' pistons on BBC?

Discussion in 'PSI Superchargers Tech Questions' started by Dunc da Funk, Oct 17, 2021.

  1. Dunc da Funk

    Dunc da Funk New Member

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    I've got the David Vizard Big Block Chevy book which discusses natually aspirated performance builds. Two of David's tips on making more power are to chamfer the top of the cylinder bore near to the intake valve and also to 'port' the pistons (reshape the crown) to get better initial flow when the valve & piston are close together, relevant section is on this forum:

    https://www.chevydiy.com/chevy-big-block-performance-pistons-connecting-rods-and-crankshafts/

    It struck me that this may be beneficial on a blown BBC too, has anybody any experience or opinions on this?
     
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  2. T-Wrecks

    T-Wrecks Member

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    When a guy writes an article on building a 700 HP BBC, I would tend to ignore everything he says. I would resource people that actually would know about boosted engines specifically.
     
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  3. Dave Koehler

    Dave Koehler Member

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    Porting pistons just sounds wrong. Modifying, shaping and getting rid of sharp edges to improve the flow path is normal in many corners, boosted or NA.
     
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  4. WIDEOPEN231

    WIDEOPEN231 Member

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    While maybe works with NA engine. I think chamber pressures that are lot higher would test these pistons in away that they can only use. Having sunkin the tops of cpl pistons with a blower I don't see having holes around piston edge as good idea.

    We ran dyke top rings and let the chamber pressure do same as porting would as to pushing rings against cylinder. Did it w/o weakening piston. Call it by any name you want drilling holes around edge is weakening the peace.

    Hey someone has to be first to try something and if you have a set of pistons that you don't mind sacrificing then this might be for you.
     
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  5. Dave Koehler

    Dave Koehler Member

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  6. Dunc da Funk

    Dunc da Funk New Member

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    I think David used the term 'port' because many engine modifiers think of anything that improves flow as 'porting'. The part that looks most appropriate is when the intake valve is close to the piston and the air from the short turn collides with the valve relief. But I have no idea whether the cut to accomodate the low lift flow spiralling past the raised crown is an issue in a blown application. Do you know of any info on blown BBC piston crown mods, pref with pics?
     
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