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Who wants to take a guess at the CCs of dish on these pistons?

Discussion in 'The Garage' started by Russell, Dec 13, 2006.

  1. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    Hey guys!

    This is a pic of my TPI engine when I had it taken apart a couple years ago, long before it became TPI. I still have those same pistons in there, but with a set of smogger heads, and a camshaft that isn't particularly built for TPI.

    I'm wanting to swap a set of mildly ported swirlport TBI heads I just rebuilt on, with an 87+ TPI lower intake I am planning on buying, then porting and gasket matching with the rest of my plenum, and swapping in a new EFI camshaft in.

    I feel some money spent up front will make me far happier with the TPI system, and will save me a crapload of tuning time invested into the chip.

    However, before I switch from a set of 78cc heads to a set of 64cc heads, I need to confirm my thoughts that these pistons have indeed got at least 10cc dishes in them. With a standard compressible headgasket, and 64cc heads, and a 10cc dished piston, my compression ratio is about 9.3:1, which is still in the 87 octane range, right where I want it.

    I know these pistons arn't particularly the best out there, in that they basically eliminate the quench effect during compression, but they are what I have, and I don't really plan on taking the bottom end apart to replace pistons, cause then suddenly new heads and a cam is gonna turn into a total engine overhaul, and cost a whole lot more than I am hoping to spend right now, lol

    Attached is a pic :)

    001.jpg
     
  2. MaxPF

    MaxPF 1/2 ton status

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    Well, the 4 valve reliefs are usually around 6cc's, so with the shallow dish and chamfer around the edges you are probably at about 12cc's. Run it, and if it pings use a higher grade of gas :D
     

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