4 port vs 8 port

Discussion of technical issues and ideas (engine, chassis)

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veecee
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Post by veecee »

Daniel wrote:
Draco wrote:Daniel according to my research it stays closed......if I look at my plenum from the top you can see the arm that controls the butterflies...and some sort of setting screw....it stays in one possition when the car is idling or off...as soon as I rev the car the arm turns opening it....
Thats where you are wrong. the are open as standard i can assure you, i have taken my intake manifold off specifically to see what they are doing. if, as you say, they are moving when you rev one can only assume that they are then closing.
i've worked on both. i cant remember exactly, but i'm 95% sure that draco is right with this.

if its like any other normal butterfly, then in its natural position it is closed. think about the throttle body's butterfly!

if the actuator works as it should, which is exactly like a turbo wastegate actuator then its natural position is closed.

the theory of ffffllllooooowwwwwww says that when the 4 butterflies are closed the air speed will increase and thus more air will get into the chambers when the butterflies and butterfly actuator are in their natural positions. its the same as when you pinch a hose pipe and the water flows out faster!!! and thats what you want while you wait for the boost to kick in!

these 3 main facts all point to fact that the butterflies will open under boost.

i can assure you of this!
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veecee
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Post by veecee »

dan...

are you sure you didnt install your system at 90 degrees to the perpendicular!!!???!!! :lol: :lol: :lol:

hahaha - i said "dic"
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Daniel
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Post by Daniel »

with all theorys of flow and hosepipes aside I am 100% positive that those butterflies are open when disconnected.
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Gary57
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Post by Gary57 »

Well they open when under boost thats for sure.
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Post by veecee »

i never get butterflies when my boost is disconnected! :lol: :lol: :lol:
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Gary57
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Post by Gary57 »

Draco any news since you connected them back up.
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Draco
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Post by Draco »

Yes I have....VC me and you are rong....unless my eyes deseved me....logicaly the butterflies should stay closed as VC and I seggested but I saw when rechecking that the arm of the butterfly is on top when the car is not started.....hopefully indidcating open....

When I start the car the arm swiwels down......with vacuum witch should be closed, if I rev the car it swings back up....opening I presume.

Did I feel any change in power....can't really say but this is what I noticed, the car is a bit smoother on eceleration and it seems as if it is using less fuel because of the closed butterflies on idle and when in vacuum....less air less petrol.

I will check the story out and report back if I am sure of anything, but for noe I changed my mind about the butterflies, previosly I thaught it sucked ass and disconnected it....now I leen towards possitive gains when it is connected, I also remember at one stage on a dyna that my car had alot of torqeu lower down whitch did not make sense, it was then disconnected and the torque seemed normal again, it also could have been because of a different dyna being used.....but the possibility that the butterflies could make a change...seems more real now.
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Gary57
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Post by Gary57 »

Great glad to hear that. Draco at what rpm do you start getting boost?? My turbo spools up very fast, 0.25Bar at 2000rpm, so I am wondering if the butterflies would even help me?!
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Post by Draco »

Gary I am not sure where it was before and where now but I will check where it starts to boost now and let you know next week.
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Post by veecee »

yes draco... i was thinking about this early this morning.

and i came to the conclusion that daniel was right. i cant remember exactly, but i will no longer argue the point with him!

i reckon the way daniel stated is probably right.

my apologies dan. you da man!

as for it being smoother draco, according to the theory, it should be! but it should also feel a bit stronger once the butterflies are open. also, the cross section area of the 8 port head is bigger than the 4 port head, so on really basic technical theory, it should allow more air to pass through, specially at higher revs.

i will find that nice link i had and post it here. it has good pics!
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Post by veecee »

hey dan,

huge apologies man... you were definitely right. i finally got around to finding those pics on the nico forums.

the link is here, http://forums.nicoclub.com/zerothread?id=185406&page=1,

and its an excellent pictorial reference for anyone rebuilding a CA18DET.

but beware - there are many hig res pics of the CA!

i chose just those that relate to this discussion!

A 4 PORT HEAD.
Image

AN 8 PORT HEAD
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AN ILLUSTRATION OF THE DIRT THAT CAN BUILD UP WITH THE 8 PORT HEADS. MY GUESS IS THERE IS NO FUEL THERE TO WASH EVERYTHING DOWN.
Image

Image

A LITTLE EXPLANATION OF THE SIZE OF THE PORTS.
Image

HOW THE PORTS BUTTERFLIES ARE ACTUATED.
Image

THE UP/OPEN POSITION.
Image

THE CLOSED POSITION
Image
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Gary57
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Post by Gary57 »

Do you not think that the butterflies themselves would be a restriction at high air flow??
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Post by veecee »

they could be i guess...

but its like saying i dont want to have sex at high air flow, because the condom themsselves would be a restriction.

or maybe like saying ...

nah, never mind... i think you're splitting pubes there sunnybooi! :twisted: :twisted:
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Post by Daniel »

lol thanx veecee, no prob mate.
I havent got the best way with communication.

Anyway those pics u put up show what i was trying 2 say about how dirty things in there are. Mine was terrible.
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Post by veecee »

have you got narcosleepy????
ReeceZ wrote:I'm sorry... I couldn't help it. Please no one wish any hateful shit on me, I own an SX already
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