CA18det intake manifold design

[Akihisa]

I pulled me engine out last night and finally paid attention to the manifold design. Now I have some questions.

- On the piece with butterfly's, I am going to remove the plates and weld up the holes. The injector placement to me is stupid. I am thinking of building up extra aluminum in between the two runners on the butterfly piece and putting the injectors so both runners would get the same fuel,(kind of like an SR)?

- In the head, there are 2 oil passages that extend into two of the runner. How much material can I take out of it before I will hit the inside of the passage?

[tyrannix]

you would definatly benefit from a junkyard CA18DE head to cut apart and play withits identical, you can do test cuts to get the info you need

besides that, Dee or that guy from CPC in austrailia would probably be the ones to ask

[float_6969]

Have you considered a UKDM head and sub manifold swap? It's a 4 port vs an 8 port, and if you don't like the current placement of the injectors, you'll like it much better on the UK head. Much more "traditional".

[Akihisa]

What I don't like about the current design is only one runner getting all the fuel. In my mind it doesn't seem to be the most effective way of spreding the fuel when it hits the combustion chamber. Do you believe, like I do, this design can be improved on without the UK head?

[float_6969]

Well first of all, the reason that it's setup that way, is so that, with the use of the butterfly's, you will gain some low end torque. I have an RPM switch wired up to control the function of my butterfly's and the system does work. It's not a 50 ft/lb increase, but definatly noticable. As far as the fuel not mixing well, I don't think that it's that much of a problem.

I do see a problem with moving the injector that far back though. First of all, you're increasing the distance that the fuel has to travel before it gets to cylnder. My main concern about this is that the fuel may start to "deatomize" (made up word?). Secondly, I don't see how there is going to be enough room to move the fuel rail back far enough so that both ports are getting fuel. PLUS, I would wonder how well the fuel would be split between the two ports.

I really think that if you're THAT concerned about the fuel distribution because of it only firing into one valve, get a UK head and sub mani and call it a day.