WTF are these holes in my manifold?

[node]

What are these tiny little ports just opposite the injector holes in my KA24DE intake manifold? at first I thought they were cold start assist but now I have no idea EGR maybe?



Thanks

[Touchdown038]

They're speed holes!

Seriously though, I have no idea. A picture without a flash might help more too.

[alex7542]

Hey if im not wrong. thats the vacuum port that goes connected to the pipe on the bootom of the intake manifold. if u look under there a medal pipe with 4 hoses connected to it. thats all vacuum. i belive thats the hole. and jsut so u know i removed those vacuums in my ka. so maybe u can do the same. just block the hoses off with big screws.

[node]

thanks thats what I wanted to know. Im in the process or removing the emissions and and that stupid set of butterflys. Im just going to use one or two vacume outlets from the back of the mani and run those to a distribution block.

[alex7542]

ok/ well i took mine completly off. and that i know off i didnt have any vacuum probvlems with my motor. but my motor is a completly different issue. i threw a rod bearing so w/e but vacuum has nothing to do wit it

[pr240sx]

Those are the PCV vaccum portsThe run to a tube under the upper manifold and then to the PCV valve.Dunno why Nissan used 4 ports for a PCV instead of a single line to the plenum.I dont recommend that you plug or modify that critical part of your engine.I tried to use bigger rubber line with a distribution block for vaccum and the car runs like crap and blew a seal. Also, oily deposits rapidly accumulated on the intake (via blowby hose)Went back to stock.Clean those suckers really well, even try to slightly smooth the holes

[node]

Nahh Im going with NO emissions whatsoever so I will be pluging them and venting the crank to atmo. BTW I alredy run without PCV and it runs fine

[pr240sx]

Or you can use a exhaust ventilationIts a check valve soldered on the exhaust stream so engine blowby get sucked by the exhaust pulses.Check for it on Summititem MRG-6002

[node]

that sounds cool too ill check that out

[Asleep Altima]

what butterflies and where are they located? ive heard talk of them, but ive never seen them...

[robertwb70]

Or you can use a exhaust ventilationIts a check valve soldered on the exhaust stream so engine blowby get sucked by the exhaust pulses.Check for it on Summititem MRG-6002

that only works with open exhaust and relatively high RPMslike drag racing-where you'll see lots of them

will not work with muffler or long/convoluted exhaust pipes or at typical street car RPMs

[robertwb70]

what butterflies and where are they located? ive heard talk of them, but ive never seen them...

the butterflies are mounted in the intake manifold-just before the head and only on the 91/92 years IIRC

[Asleep Altima]

ahhh, thank you, didnt know that... what are their purpose?

[robertwb70]

they are supposed to increase low RPM power by increasing velocity and swirl of the incoming air-it's sort of a crutch to make up for the disadvantages of 4 valves per cylinder(reduced low RPM power) there are many ways manufacturers try to accomplish this since low RPM power is so precious in 4 cylinderslike long tuned intake runners(like our motors and older chevy TPI systems) valves that restrict some of the runner area(the valves we are talking about-similarly the old corvette ZR-1 had 2 runners per cylinder for the same effect) and of course other are doing it with variable valve timing(like hondas VTEC)

nissan eleminated these valves in later engines-and when they did they also reduced the cam duration to get back to what they considered acceptable low RPM power-I think they might have made the intake runners a little smaller also-but I've never had one of the newer(non valved) intakes to check

everythings a trade off so they size the runners/valves/cams for the power they want and then try some clever ways to minimize the down sides

[Asleep Altima]

kewl, thanks for the info.

[node]

the butterflies are mounted in the intake manifold-just before the head and only on the 91/92 years IIRC

Uhhh so my 95 engine doesent have them, hmmm mabe I should have that intake ported instead.