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gibbon

Ca18det inlet port spacing

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Wondering if anyone could help me out here, looking for the port size and spacing for an 8 port ca18det inlet manifold? For a project, alrwady tried a TVIS 4age but too small overall... 

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I have one, but it's a really early version and has a cross over manifold with a TVIS like contraption on it. Is it worthwhile measuring that?

 

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All the non nzdm/euroDM CA18's had like the Tvis shizz going on. 

But there was also the very earliest DOHC CA18, which had the different intake. (Is that what you're talking about?) I've got one of those motors in the shed actually. (Sans the unique manifold sadly)  I've got a 4 port head too. Also fairly sure I've got a spare (standard later style) 8 port manifold for measuring purposes too.

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Pics too huge... I also have the head. I was planning on using it. I had gone through the effort of hand cutting new gaskets. But then the tuner I was going to use was like "LOLWAT! Find a normal one".

20200704_105320.thumb.jpg.e5932a835837eea0800bf2fc9c786912.jpg20200704_105303.thumb.jpg.805d87b10ac2044b1fb1894f375ae5a2.jpg20200704_105407.thumb.jpg.4961e0634e5b5e9750ff6226dbcc317f.jpg

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That's actually looking pretty promising, the only measurement missing is the size of the center gap... what the heck are those elongated ports for?

Interested to see if the later manifolds share the same spacing, I'd prefer a throttle body on the end rather than a top-loader 

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Oh and the distance between the centres of the two outermost ports, if its anything near 310mm I'll be a happy man indeed 

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Just now, gibbon said:

That's actually looking pretty promising, the only measurement missing is the size of the center gap... what the heck are those elongated ports for?

Interested to see if the later manifolds share the same spacing, I'd prefer a throttle body on the end rather than a top-loader 

AFAIK, the long skinny runners that go to the 4 ports shaped like an 8 are to increase the velocity of the air at low revs. To get more air in? For increased bottom end torque? As the revs increase the butterflies open allowing the air to go through the big short runners and feed all 8 inlet ports.

The downside to this is if you use only low revs, 4 of the ports/valves are blocked most of the time and you get lots of carbon gunk built up behind those 4 valves. When I stripped that engine there was big piles of gunk stacked up behind those 4 valves. 

Just now, gibbon said:

Oh and the distance between the centres of the two outermost ports, if its anything near 310mm I'll be a happy man indeed 

I did not move the ruler between photos. So the measurement is there... 299mm. Sad man.

Oh yeh and the center gap.... is 183mm-149mm = 34mm

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My centre gap is 35mm, and an 11mm overall discrepancy just means 5.5mm each side, I need an adapter plate anyway so can incorporate that, so still pretty keen, if the spacing is the same on the later manifolds. I need a fwd manifold to get the tb on the right end, what does that leave me looking for... turbo bluebird engines? 

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1 hour ago, Adoom said:

Pics too huge... I also have the head. I was planning on using it. I had gone through the effort of hand cutting new gaskets. But then the tuner I was going to use was like "LOLWAT! Find a normal one".

20200704_105320.thumb.jpg.e5932a835837eea0800bf2fc9c786912.jpg20200704_105303.thumb.jpg.805d87b10ac2044b1fb1894f375ae5a2.jpg20200704_105407.thumb.jpg.4961e0634e5b5e9750ff6226dbcc317f.jpg

Looks like a u11 version

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And a pic of my four port manifold, just for the thread.

Note the injectors are centralized. So you wouldnt get that scummy build up on the valve for the port with the butterfly which doesn't see any fuel in an eight port motor

Screenshot_20200704-192046_Gallery.jpg

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Yeah that's the other odd thing I noticed, the offset injectors. So once those butterflies open, you get pure air coming out of the "secondary", and an air/fuel mix from the primary.. I wonder how well it actually mixed at high RPM 

Any chance I could convince you to part with that 8 port manifold? Not fussed about the missing butterflies 

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Yeah I probably dont need it. It came as a spare with my "good" CA18det. 

What are you actually building?

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I've got a 12 valve 4g63 head, it has 8 inlet ports in a very similar pattern to the ca18det. The engines only came with a garbage single point injection, and the 12 valve heads cant be fitted with a magna MPI inlet like the 8 valves can. Since starting this thread I've picked up a 4age silvertop ITB inlet I'll try and fit up to the other side of your 8 port section, that'll face the right way at least. Shoot me a PM, cheers 

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