Cheap Custom RB20/25 Intake Manifold

[Sileighty_85]

Well for those of you who dont like the cross over style of the RB intake Mani.

I found a cool little artical in one of my Option Mags

Sorry i dont have a scanner lol



Definatly cleans up the engine bay real nice

[burnsauto]

yeah that was always a neat little trick for those not wanting to blow 8 bills on a greddy manifold. Option mag always pushed that mod, its been in a few issues.

[Grenade180sx]

so whats the price? who makes it?

[91rps13]

so whats the price? who makes it?

it looks like the stock one was just modified.. cut and weld. pretty good stuff though.

[Chernobyl]

Seems to me like the stock setup would distribute the intake air more evenly across all cylinders.

[Mx_Eva]

I would be concerned about air flow to the back cyl. The design of the manifold is to distribute air evenly. People running this would find their back two cyls probably running lean, possibly even the 1st cyl.

I mean, if you are really concerned about just having a cleaner engine bay. :shrug:

[5150Fab]

should be fine. thats a good idea. if you were really worried about it you could always put a taper on the back of the manifold by the back 2-3 cylinders.

if i had an rb i would do this without any worries for sure.

[opponheimer]

Originally Posted by Mx_Eva

I would be concerned about air flow to the back cyl. The design of the manifold is to distribute air evenly. People running this would find their back two cyls probably running lean, possibly even the 1st cyl.

I mean, if you are really concerned about just having a cleaner engine bay. :shrug:

wouldn't you mean running rich?

[5150Fab]

i dont know if thats what he ment but yes it would make a rich condition if anything. this is why it really wouldnt worry me. Im sure everything would still get burnt up and wouldnt effect anything. It probably wouldnt even make a difference honestly.

[eh?]

It would be lean not rich. There will be no restriction back there and air would rush to the aft cylinders instead of being slowing down by the tapering that is used in all aftermarket rb manifolds. The aft cylinders alreay run hot and being a bit more lean isn't going to help.

[burnsauto]

the back is tapered. look at the 2nd and 3rd pics.

[Mx_Eva]

Originally Posted by opponheimer

wouldn't you mean running rich?

Well, it could and most likely would. As it will create a turbulant pocket of air that will create a lack of flow into the last 2 cyl. and it's possible the 1st cyl will see most flow blast right past it.

The amount of work done to creat this manifold (cutting, new material, welding, etc) you could create a properly designed one as well.

the back is tapered. look at the 2nd and 3rd pics.

There is no taper in the pictures.

Here is essentially what this manifold aims. There are no velocity stacks in the RB20 Manifold, and it has 2 extra cyl. however the principles are the same.



With just a bit of taper you see improved results here.



And the best results when angling the TB placement.



and

[eh?]

Originally Posted by burnsauto

the back is tapered. look at the 2nd and 3rd pics.

It's not, i've owned a few RB25. The lower section has different length foward and aft runners to merge neatly at the upper manifold.

[sillyvia13]

well after readin the entire thread... I am pulling my intake off now!
FUCKING A! sick.

I wonder if q45 tb will look nice?
time to cut up q45 mani and use flange, I knew i kept that for a reason.

[efrain240sx]

^^^ that's the spirit =), do it and report back with some pics