What Exactly Are The Differences Between R33/r34 Rb25T Inlet Manifolds ?

[discopotato03]

Yep I see what you mean R33 TB wise . The Neo plenums mount flange doesn't have the extra material to cover the back of the barbs hole like the R33s plenum does .

Thanks but I know someone who I think still has R33 upper and lower manifold halves bare . What I want to do is measure the diameter of the ports where the upper and lower halves of the R33 version bolts together . I measured the Neo Turbo version and the ports are just over 41mm diameter - around 41.2mm . The Neos shim gasket is a very neat fit here .

A . 

[discopotato03]

Hi all , finally got to measure the difference in bore size between R33 RB25DET and R34 RB25DET inlet manifolds where the plenum bolts to the lower legs .

As you'll see its close to 6mm which is considerable . From what I've seen in the past many RB manifolds , except RB26 , seem to be reduced in size or shape in later versions .

Nissan obviously thought higher gas speeds and possibly a lesser plenum chamber volume was way to go on the GTt along with head and piston differences .

The pic with my grubby finger in it is pointing to the water inlet to the Neo's front bleeder , I'm curious to know if the pipe size and hose is the same size as the hose up from the barbed fitting behind the water pump on R33's .

As I've said in the past there's heaps of minor changes all over the Neo 25T and all look to be a step in the right direction .

A .   

Edited October 21, 2017 by discopotato03

[acsplit]

Now I am tempted to try this on my r33 RB25det motor... 

Would mean good injectors in a stock rail and closer to looking like the r34 I am putting it in.

[discopotato03]

The most involved part is making up a spacer plate if you want to use the R33's throttlebody and TPS on the Neo 25's manifold . I was given an R33 manifold top section so I cut its TB flange off and machined the rough side flat in a centre lathe .