Lower Manifold Porting

Discussion in 'Technical' started by Jordz, Mar 21, 2014.

  1. Jordz

    Jordz Fashionably Late

    Ill be porting my lower manifold and heads soon and ive notice the manifold has what i can only describe as an air inlet running to the injectors runner on each side. Its basically just a little hole going from each runner to just under each injector. My assumption is this design is to create a higher velocity for the fuel as the spray mixes with the air, but i have my concerns that in a boosted engine it may actually negatively affect the spray pattern, due to the turbulence of the air being forced through it. Has anyone ever tried blocking off these little channels, or know if there would be any pros or cons to blocking them?
     
  2. rob260

    rob260 Administrator Staff Member

    Putting the spray under vacuum is a good thing -id leave it alone
     
  3. Jordz

    Jordz Fashionably Late

    Cheers. Thats all i needed to know :)
     
  4. syntax_X

    syntax_X Zed Head

    Its actually there to help spray pattern while boosting :)
    Series 2 lower plenum doesn't have those holes at all, but the injectors are pintless* and such..


    *Pintle-free? Unpintled? Decompintleated?
     
  5. Jordz

    Jordz Fashionably Late

    Pintleless :D

    And ill be running pintleless injectors due to future-proofing my engine for e85 ;)
     
  6. rob260

    rob260 Administrator Staff Member

    It'll still be a series 1 manifold and vac will help draw the wider spray through narrow ports
     
  7. syntax_X

    syntax_X Zed Head

    If your going pintleless injectors do yourself a favour and buy an s2 lower plenum.
    Or else you'll be running o rings galore to get them to seal and they'll be sitting too high.
    I have a thread somewhere that goes into more detail with the differences and such.

    Just get s2 lower plenum.and fuel rail, and do it right the first time.

    Just gotta port your s1 heads to match...
     
  8. Jordz

    Jordz Fashionably Late

    Most likely going top feed at this point sooo....gonna stick with my plenum for the time being.
     
  9. syntax_X

    syntax_X Zed Head

    Your still going to have to use a mess of O-rings to get the rail to fit unless its custom made for that purpose, and even then the injectors will be sitting far higher than the lower plenum was ever designed for...

    My s2 lower is on an engine atm so i cant show you the exact differences unfortunately.

    But if you decided to go top rail, pintleless and S1 plenum, buy yourself an S2 lower plenum gasket kit and port match to that (carve out those hole, they're a big square cutout on S2's) or your spray patten will be farked.
     
  10. Jordz

    Jordz Fashionably Late

    Haha still a little lost as to what you mean, but ill look into it. Cheers for the heads up man.
     
  11. syntax_X

    syntax_X Zed Head

  12. BLACK BEAST

    BLACK BEAST SLICKTOP TT R-SPEC

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