so a little while ago i brought a RB20DE NEO as after a few drunken conversations with Spence we decided it should have better ports for NA as it was about this time that most car manufacturers did this kind of thing. i couldn't find much on the web about them so i just brought one to see what the differences were. after a quick inspection it didn't seem much different. bummer. till today when i pulled it apart.
a series one RB20 port. pretty average.

and the NEO port. hello valve bases i can see you.

so it has proven to be a worth while purchase for a base to start with.
so the reason i pulled all the intake manifold off was im looking at building my ITB intake. now the top radiator pipe comes of the intake manifold on RB's and after looking at a few of my earlier RB's where this is all one cast unit it was looking like i was going to have to do some cutting to make my manifold. but the NEO has the water/injector section of the intake manifold separate and this is a picture of it.

cool so all i need is a flange and i can make my ITB runners but wait what is the vacuum actuator under the manifold and in the ports of this section are these.

vacuum actuated butterfly's right up by the head. WTF? why would these be there? also the 2 round holes above the port are bypasses to this butterfly and come out the head side like this.

i thought this was very weird. ive never seen something like this before. can any one shed any light as to why?
i was thinking about ditching the GTR throttles and using that as my throttle butterfly's but then thought it would be much better with the butterfly's much further away from the head as to build up some vacuum in the runners. so what i will probably do is turn up some little alloy bungs and weld them in the bypass holes on the intake manifold side and then port out the head side and remove the butterfly's to make a straight through even port in this section which is sweet as it will mean injectors are already in there and don't have to fuck round with the water circuit. then all i need is a flange and make some intake runners and slap GTR throttles on the other end. any opinions on this idea is welcomed though.
stay tuned.