R33 And R34 Rb25Det Lower Inlet Manifolds Interchangeable ?

[discopotato03]

I've been looking at pics of R33 and R34 RB25 DET manifolds and I'm curious to know if the R34 GTt lower manifold can be substituted for the R33 one .

Main reason is to fit the GTts top feed fuel rail and retain all the R33s plenum (plumbing and IAC valve) .

If the gasket that fits between the upper and lower manifold halves is the same it may work .

Fingers crossed cheers Adrian .

[TheGeniusMoose]

Different mate.

A Greddy R33 RB25DET does not fit up to a NEO

[iruvyouskyrine]

That's only because the IACV is a different shape, which bolts on to the top half of the manifold anyway.

Disco I reckon that they would be the same, if not very very similar. Cannot say for sure if they would be interchangeable though.

[scotty nm35]

Is the gasket the same part no?

[Griffin]

I have swapped the whol setup over personally

[Blackkers]

What's stopping you from swapping the top half as well?

[discopotato03]

Turns out that the flange and bolt pattern is different R33 to R34 RB25DET .

A .

[AngryRB]

I think the r34 manifold has the opposite bolt configuration, more bolts on the strut side which looks like it might prevent leaks better?

[Blackkers]

bummer. This would look more stock than one of those cheapo anodised top feed rails and could probably have been done quite cheaply at home

[AngryRB]

has it been confirmed that a stock r34 rail wont fit a r33 manifold?

[scotty nm35]

I haven't fitted a Neo rail to a 33 so I don't know how far out the rail bolts are, but I think it would be fairly easy to fit, seeing the aftermarket rails have room. The lower spacers are only available in kits, but they are so easy to make on a lathe. The spacing for the rail bolts should be easy enough to fix. If a conversion kit was made it wouldn't cost too much in bulk...

The early WRX owners have similar issues converting from side feed to top, but a few companies have worked it out and now they sell similar conversion kits to what you RB guys need.

[AngryRB]

It really isn't hard to fit aftermarket rail as Arts did, and i did with 1000cc xspurts, just some stuffing around but very doable. Just paint it black for stealth look.

[discopotato03]

Not impossible to get the Neo rail on but probably more stuffing around than its worth .

If you look at the R33 RB25 lower manifold the side feed rail mounts at three points sort of below the rail . The GTt one mounts above the rail on the cast in water passage . The 33 manifold has similar mounting points for something else but they are closer together than the GTTs ones .

You could weld mounting pads to the lower manifold if it was off but most don't feel like removing it and it becomes a unique part .

If keen you could cut and weld different mounts on the GTT fuel rail but it's cad plated and could peel off inside and leave bare steel which isn't flash .

EFI Hardware advertises an adapter system that screws into the front of aftermarket rails to take the Nissan style rail mount reg so if it fits ARTs rail that makes life very easy . I think the rail has to have "machined O ring port" threaded sections back and front for this adapter to fit but I don't know enough about aftermarket rails to know if they are all like this .

I can lay my hands on a Nismo adjustable FPR and I'd like to know if their bypass port is any larger than the standard one .

A .

Edited June 8, 2014 by discopotato03

[scotty nm35]

Yep. I saw that. I agree a black rail isn't too obvious and it's not that expensive, but the amount of those crappy fiveO injectors being sold shows how keen people are to keep the stock sidefeeds, no matter the consequences. I would love to be able to supply some easy way to swap over to top feeds for those guys that want a stealth upgrade. I like stealth options.

[discopotato03]

Yep I tend to think an aluminium rail in natural finish or matt/flat black would be alright provided the fittings aren't some silly nail polish colour .

It seems the -8AN (3/4 x16) parallel thread is a defacto standard and seals with an O ring on a bevel in the ends of most aftermarket rails .

I reckon if the EFI Hardware adapter parked a standard or equivalent reg on the front of a plain rail it shouldn't attract too much attention and at least put the return line where it's supposed to be .

A .

[scotty nm35]

So have you given up with the Neo rail Disco? Send it down so I can do a fit up on a 33, I might be able to work something out, anyone in Melbourne got a spare lower plenum?

[discopotato03]

Starting another thread on aftermarket top feed rails for R33 GTS25Ts .

Scotty not totally given up but done properly an aftermarket rail would be easier .

A .

[XRATED]

Why not just put top feed rail and short injectors in your r33 intake? Just have to llose

... that's what I'm running in my drift pig? r33rb25det, aeroflow rail, ev14 1000's.

J.

[scotty nm35]

He wants the stock look as much as possible, stock reg at the least.

The Aeroflow rails are set up for mid (3/4) length injectors, using the short ones requires shortening the spacers which scares some people.

[XRATED]

Fairenough...

Spacer between upper and lower halves?