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Intake and Exhaust Valve Sizes

Discussion in 'The Hokey Ass Message Board' started by grovedawg, May 24, 2010.

  1. grovedawg
    Joined: Oct 20, 2009
    Posts: 451

    grovedawg
    Member
    from Heber, UT

    What is the "optimal" Intake Valve to Exhaust valve ratio for a strong engine? I've read 70-80% is about the right ratio to maintain low end torque and driveability for a street motor. What have you guys experienced?

    I'd like to run a 2.02 intake and a 1.64 exhaust valve. That would put my ratio about 80% (the upper threshold from what I've gathered....)
     
  2. grovedawg
    Joined: Oct 20, 2009
    Posts: 451

    grovedawg
    Member
    from Heber, UT

    Any Ideas? Uninteresting topic?
     
  3. Parts48
    Joined: Mar 28, 2008
    Posts: 1,579

    Parts48
    Member
    from Tucson, Az
    1. Hot Rod Veterans

    What engine ? What build ? Heads..cam etc.
    Sounds maybe like a SBC..but without more details it's difficult to know what to say.

    A stock low CR head with mild cam really not going to do much more..maybe less with 2.02s..
     
  4. Deuces
    Joined: Nov 3, 2009
    Posts: 23,753

    Deuces

    1.94 intake valves and 1.50 exhaust valves should do the trick on the street. Just don't bolt on anything bigger than 1.500" primary tube headers... If you have the 1.600 exhaust valves, you could go with 1.625" primary tube headers...
     

  5. The ratio is not determined by a simple linear comparison of the diameters of each valve. You need to compare areas.

    In this case the area of a 2.02 valve is 3.2 squ. in. and the 1.64 valve is 2.112 squ. in. The ratio of exhaust to inlet then become 0.66:1 or 66%.
     

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