1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

VTEC Intake Valve V. LS Intake Valve

Discussion in 'Engine Building' started by brian11to1, Mar 10, 2005.

  1. brian11to1

    brian11to1 Senior Member

    Messages:
    9,203
    Likes Received:
    21
    Joined:
    Jan 9, 2003
    VTEC Intake Valve = 33mm
    LS/B20 Intake Valve = 31mm

    Im getting all my research finished up so I can start accumulating parts for my 11.5:1 B20B All Motor Build. This far I've decided on:

    84mm IB Spec 11.5:1 Pistons
    IB Spec I Beam Rods
    Line bored GSR Main Girdle
    Crower 62404 Cams
    Crower Dual Valve Springs w/Titanium Retainers
    this is just a simple list the real list is much longer

    My question is... would I benefit from cutting new valve seats to seat a VTEC valve (33mm) into my LS Head (31mm I. Valve)? If I had my "porter" do this would it be beneficial to me. What would be the pro's and con's of having larger Intake Valves. Are they better for higher RPM's or what? Thanks

    Brian
     
  2. erebunicrx

    erebunicrx my name is Dale

    Messages:
    2,110
    Likes Received:
    1
    Joined:
    Jun 13, 2003
    Location:
    Bristol ct
    i think its going to shift the whole powerband up. you may have a better peak hp but alittle less bottom end. you might be better off looking for a p8r head. im not sure how much your going to pay for the new valves but the p8r comes with the 33mm intake valves anyway.
     
  3. brian11to1

    brian11to1 Senior Member

    Messages:
    9,203
    Likes Received:
    21
    Joined:
    Jan 9, 2003
    How hard is it to find a P8R head?
     
  4. erebunicrx

    erebunicrx my name is Dale

    Messages:
    2,110
    Likes Received:
    1
    Joined:
    Jun 13, 2003
    Location:
    Bristol ct
    my motor came with one. but on h-t there are people selling them. the problem with the p8r head is noone has built one that i know of and i had problems with my 404 cams. the valve spring was coilbound on the intake side at a 440 lift. so i had to get 8 ret from crower from a h22. idk if this is going to work but thats what brian crower said would work. i will find out very soon though.
     
  5. erebunicrx

    erebunicrx my name is Dale

    Messages:
    2,110
    Likes Received:
    1
    Joined:
    Jun 13, 2003
    Location:
    Bristol ct
    also the p8r head has a 84mm combustion chamber
     
  6. brian11to1

    brian11to1 Senior Member

    Messages:
    9,203
    Likes Received:
    21
    Joined:
    Jan 9, 2003
    What was the deal with the Spring? I didnt understand that. It cant have an 84mm comb. Chamber... thats more than double the size of any B series.
     
  7. erebunicrx

    erebunicrx my name is Dale

    Messages:
    2,110
    Likes Received:
    1
    Joined:
    Jun 13, 2003
    Location:
    Bristol ct
    your combustion chamber now is 81 with the regular b20 head. the p8r is only 3mm bigger and makes it the same bore as the block. im still not sure what was wrong. maybe the valve seat on the intake sits alittle higher so there where no clearence isues with the piston to valve cleaence. but im not sure.
     
  8. brian11to1

    brian11to1 Senior Member

    Messages:
    9,203
    Likes Received:
    21
    Joined:
    Jan 9, 2003
    C-Speedracings Comp. Calc. says the volume of the LS Combustion chamber is 45 cc...
     
  9. erebunicrx

    erebunicrx my name is Dale

    Messages:
    2,110
    Likes Received:
    1
    Joined:
    Jun 13, 2003
    Location:
    Bristol ct
    right and the p8r is 49 cc's. the diameter of the combustion chamber is 84mm. just like you pistons are 81mm. the cc's are measured by amount of liquid in the combustion chamber in cc's.
     
  10. brian11to1

    brian11to1 Senior Member

    Messages:
    9,203
    Likes Received:
    21
    Joined:
    Jan 9, 2003
    Dayum.... learn something new every day
     
Verification:
Draft saved Draft deleted

Share This Page