Engine Displacement Questions

Discussion in 'The Safe Zone' started by ElrodKTPQ_89, Aug 11, 2014.

  1. ElrodKTPQ_89

    ElrodKTPQ_89 Legend

    Messages:
    5,068
    Likes Received:
    127
    Joined:
    Aug 6, 2013
    Location:
    Crossett, AR
    Ok at the risk of me looking like a dummy :tongue3: I have a couple of questions. I figured this would be the best place to ask such questions in also with out getting shot down, lol.
    After having my engine (5.0) bored .20 over, what does that make my engine displacement? I'm guessing not a 306, but I don't really know what to tell people when someone asks, lol. But then at the same time what is done different to build a 306, 331, or 347? I guess I don't really understand all the bore/stroke and how you calculate displacement based on that. And also how do you determine size in liters? Somebody enlighten me, I love to learn! I know I should know all this stuff just never was taught I guess :undecided:
     
  2. Addermk2

    Addermk2 Well-Known Member

    Messages:
    2,505
    Likes Received:
    32
    Joined:
    Mar 7, 2006
    Just tell people its a 302, 20 over.

    People are going to think you're retarded if you say its a 305 (304.62)
     
  3. kb1982

    kb1982 Active Member

    Messages:
    591
    Likes Received:
    4
    Joined:
    Aug 10, 2013
    Location:
    Kentucky
    A stock 5.0 has a 4 inch bore, and a 3 inch stroke crank. To get more cubes, you can increase bore, stroke, or both. Since you can only bore an engine so far before the cylinder bores get to thin, and issues arise, people add more stroke to the crankshaft. A crank with a 3.250 stroke makes a 331, and 3.4 stroke crank is used in 347 stroker. This is with stock blocks. After market blocks such as the Dart blocks can be bored out considerably bigger, all the way to 4.185. So the max size with a 3.4 stroke and a 4.185 bore in a Dart block would give you a 374 (374.15) There are such things a short rod stroker and long rosd strokers but that is a different can of worms. Here is a good website to calculate displacement. http://www.wallaceracing.com/cid.php
     
  4. RichV

    RichV Well-Known Member

    Messages:
    4,227
    Likes Received:
    247
    Joined:
    May 6, 2012
    Location:
    CO
    D=(pi)/4 (B)[SUP]2[/SUP] x S x N

    D=displacement
    B=bore
    S=stroke
    N=number of cylinders

    To convert to Litre, you multiply ci by 16.39cc/ci and end up with cc, then divide by 1000 for Litre.

    A 306 is just a .030 over 302.
    A 331 is a stroked 302, so is a 347. Stroked means it has a aftermarket crankshaft that increases the stroke. Bore is the same.

    Standard 302, B=4" S=3"

    Pi/4 x (4x4) x 3 x 8
    3.14/4 x 9 x 32
    =301.59ci x 16.39 = 4943cc which is a 4.9L

    What?? My 5.0 is actualy a 4.9???!!!!
     
  5. ElrodKTPQ_89

    ElrodKTPQ_89 Legend

    Messages:
    5,068
    Likes Received:
    127
    Joined:
    Aug 6, 2013
    Location:
    Crossett, AR
    My thoughts exactly.

    Thanks that cleared up a lot for me actually. I was aware of only being able to bore a stock block so much, but I didn't know what difference a bigger crank made.
    Thanks Rich! After reading that formula now I know I've seen it before but just forgot. Thanks for all the info guys!
     
  6. D3VST8R96GT

    D3VST8R96GT Well-Known Member

    Messages:
    3,996
    Likes Received:
    83
    Joined:
    Feb 19, 2009
    Location:
    SE Georgia!
    Summit racing compression ratio calculator will do the math for you...