Intake Manifold Butterflies

[fanta]

I was cleaning up a spare manifold and had a couple of question on the butterfly assembly. It closes in vacuum and opens up when it drops, correct? Is there more to it? How beneficial is the setup? Would removing it cause a considerable loss of response in low throttle/air conditions?Thanks in advance.

[KaZ (VaBch)]

Butterflies are closed for low RPM to increase torque... then open at high RPM for more HP. Removing them completely allows for additional high RPM HP, but you lose a good bit of low end oomph when they're completely removed.

[paul_s13]

Removing them completely allows for additional high RPM HP, but you lose a good bit of low end oomph when they're completely removed.

I went to the 4 port head and lost no low end at all, but when I did have the 8 port head the car felt worse low end with the butterflies connected.

[fanta]

How exactly are they actuated? Crossover point?

[fanta]

Is there a year/region breakdown for the 4/8 port assemblies?

[biosehnsucht]

UK/JDM

[paul_s13]

The UK/Europe/South Africa got the 4 port, the rest got the 8 port, the butterflies are actuated when the boost is enoughto open the butterflies actuator.

[rico05]

So any of you UK guys wanna ship us US guys UK heads and manis?;)

[Nismo1182]

When I diconnected my butterflies, the car felt better.

[fanta]

When I diconnected my butterflies, the car felt better.

Could you elaborate a bit?

[KaZ (VaBch)]

Well I was just saying, I believe that was the way the functionality was described previously... £0£

[NeedCAforS13]

I have no butterflies in my manifold, and my car feels fine down low... I would like to drive another car with the butterflies, but it seems everyone here in Orlando removed theirs!

Sean

[ca18det_boy]

Hey sean did D remove his or does he still have them on?

[Nismo1182]

Could you elaborate a bit?

I originally had it with one vaccumm line going to a T. One end of the T went to the FPR and the other end went to the buttlerfly actuator.

One day I decided to unplug the line going to the actuator and cap it off at the T so as not to have a air leak. The car felt smoother down low after that so I left it unplugged.

[Nismo1182]

I have no butterflies in my manifold, and my car feels fine down low... I would like to drive another car with the butterflies, but it seems everyone here in Orlando removed theirs!

Sean

When you drove my car the first time they were still working.

Im sure my friend hasnt removed or unplugged his.

[float_6969]

Well I've driven mine with them hooked up for a while, but since I've got everything apart right now I'm going completely remove them. (rod and all). I'll have to have some welding on the mani done, but no big deal. We'll see if there is a difference....

[NeedCAforS13]

When you drove my car the first time they were still working.

Im sure my friend hasnt removed or unplugged his.

wait, the first time like when I was living at my old house? I think it was quite a bit less responsive at high rpm's than my car... might be because of my different turbo though.

I would like to drive your buddy's car, or at least ride in it, if he ever comes out to the wednesday meet... sucks I have to work again this week though:(

Sean

[boost_boy]

They work better for N/A CA18DE engines. They are almost useless on the DET, but I guess nissan saw that it was cheaper to just leave them on there instead of making two different intake manifolds. Why they gave the UK 4 ports beats the crap out of me . I had the buterflies working on my G/F's car and the car was lazy in the lower RPMs. And when I added no vacuum which left the butterflies open, the car had a little more life down low.

Dee

[paul_s13]

Why they gave the UK 4 ports beats the crap out of me Dee

Coz were great! :pface

What you need is the head/manifold and fuel rail, if anyone is really interested then look at http://www.sxoc.com/vbb in the for sale section.

[NeedCAforS13]

any idea what shipping would run on one of those paul?:)

Sean

[Nismo1182]

wait, the first time like when I was living at my old house? I think it was quite a bit less responsive at high rpm's than my car... might be because of my different turbo though.

I would like to drive your buddy's car, or at least ride in it, if he ever comes out to the wednesday meet... sucks I have to work again this week though:(

Sean

He was out there last week for a long time. I'll see if he can come out this week again.

[fanta]

I pulled them off of a spare butterfly block. Later on I'll probably test the differences between the two.

[paul_s13]

any idea what shipping would run on one of those paul?:)

Sean

I don't have a clue mate.

[float_6969]

shipping to the US from the UK would be killer I think. especially for that kind of weight. I'm just gonna take mine out completely. We'll see how the car behaves afterwards.

[fanta]

I'm simply going to tap the ends for a bolt and keep the holes betwen the ports. Really shouldn't be much of a problem, might add some turbulence

Not enough of a n issue for me to work on.

[SSSCA18DET]

I've actually just done this mod (today), the butterfly's are pretty easy to remove. To remove them, I found it next to impossible to unscrew, I ended up drilling them off the rod, and then the rod slid straight out.

Over the the drill press, open the holes on the end of each 'half' of the manifold, and then tap for a 1/8 BSP plug. Nice and easy.

Might as well match port whilst its all apart.

I've seen the pics of the 4 port heads, I recall having seen those in Australia at some point (I'm in Melbourne).

From memory they were on an early CA18det (FWD) from a pintara (non intercooler version).

Not much use for RWD but though you may be interested.

[float_6969]

Yea, I planned on drilling mine out. I stripped out the head on 2 of them and gave up. Don't really need to keep them anyway...

[SSSCA18DET]

Here is the cetre section with the butterfly's removed, I drilled them out.

I've started to port match the manifolds to each other also.

In the pics you can see the 1/8 BSP plug I've used to block of the ends (where the rod used to be).

I'd suggest you use these instead of a bolt as they are tapered and you are more likely to get a better seal (I'd hate to have to pull the manifolds off again to fix this).

[SSSCA18DET]

Pics

[SSSCA18DET]

As you can see I separated the two parts of the manifold to make it a little easier to work with. FYI - the screws that hold the manifold together most likely will need an impact driver to get out.

As can be seen, you dont need to take too much meat out of the walls to tidy it up, just a little. The parts shown, are only half done as the manifold to head side still needs to be done. The main thing you would want to get to is the ridge that the butterfly used to sit on, you can see it in the second pic if you look closely.