Who else has done/tried this?

Discussion in 'High Tech Retrofits' started by Lance Von S, Jun 25, 2017.

  1. Lance Von S

    Lance Von S New Member

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    I have a 4.8L iron truck block I pulled out of my 02 GMC Sierra. I've read you can bore the cylinders to 3.898" and fit LS1/LS6 pistons. The crank is also small so I would find a 3.622" from another block (like a 5.3 or LSx from the yard). Effectively turning this engine into a 5.7L (346ci).
    I've found pistons that will work with the stock rods and crank size I'm aiming for (cause the 4.8 and 5.3 have slightly different rods)
    Anywho the whole thing is on an engine stand and parts somewhat organized in a crate. I have an 80 Camaro (Berlinetta) and I'm wanting to drop this block in once I'm happy with it.
    Unfortunately it turns out the 4 speed is a Saginaw (not the best I hear). Lord knows I want be taking it too easy on this thing, so I can either a) Find a better 4 speed and buy the conversion kit as well. Or b) buy another automatic transmission to hook up to the LS I have. (Truck had a 4L60E)
    I guess I'm looking for some opinions on doing this to the iron block ( being that it'd probably be cheaper to get a crate motor in some instances). Those are the cards I'm dealt, I've never put an engine back together yet but I'm confident I can do it.. I definitely want that under my belt. (Hense all this bs instead of just buying a crate motor)
     
  2. badazz81z28

    badazz81z28 Veteran Member

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    Your best bet would be to have a machinist sonic test the block and see how thick the bores are and how much you can safely bore out. Many people have turned iron 5.3s to 5.7s. Even still IMHO you're better off with a LS3
     
  3. 57Plymouth

    57Plymouth Veteran Member

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    I don't think you can punch a 4.8 to a 5.3 or 5.7. You would probably spend less in machining and custom pistons to buy a 5.3.
     
  4. Lance Von S

    Lance Von S New Member

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    Pistons in the 5.3 and 4.8 are the same bore size, so getting a 5.3 I'd still need bigger pistons..the bigger crank is what separates the 4.8 from the 5.3.
     
  5. Lance Von S

    Lance Von S New Member

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    So most people doing the conversion would sonic test?
    But yeah.. at the end if the day, I'd much rather a LS3/7 or LQ4
     
  6. badazz81z28

    badazz81z28 Veteran Member

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    I'm not sure what people actually do, but that's the proper method before boring out a block.
     
  7. nobreaks254

    nobreaks254 Veteran Member

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    ive had several 4.8/5.3's bored out to ls1 bore (3.898). Never had an issue. Bored out a few lq4/lq9 blocks to 4.065 (ls3 size) as well. Boring out the bigger bore blocks is alittle riskier and really should be checked but I never did.
     
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  8. Lance Von S

    Lance Von S New Member

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    Would you just change out pistons or the whole rotating assembly like I'm trying to do? How much would it typically cost? (US/CAD)
     
  9. nobreaks254

    nobreaks254 Veteran Member

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    I would at least use a 5.3 rotating assembly, make sure to get it rebalanced with the new pistons. My machine shop charges alittle more to bore out the 4.8/5.3 blocks to that size since they are removing so much materail. I think I paid less than 300 last time. They also only charge like 45 to sonic check the blocks but they have to get the tool from theyre other shop a couple hundred miles away so I never bothered.
     
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  10. badazz81z28

    badazz81z28 Veteran Member

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    You all would be way ahead to just get a truck 6.0 instead of trying to punch out a 5.3. Unless you want to break into the rotating assembly for forge pistons etc
     

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