Build thread for RB25NEO

Discuss the RB20, RB25 and RB26 series engines.
godzilla_753
Posts: 125
Joined: Sat Jan 27, 2007 1:55 pm

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Hi guys,

Ive had my RB25 neo swapped s13 for awhile now and I think its time for some upgrades :naughty:

I figured it would be nice to document some of this, since theres still not a whole lot of information on some of the things Im going to do for my build, and maybe itll help someone else out. Plus this is my first build thread, and I wanted something worthy of it.

Most recent pics before the tear down:
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godzilla_753
Posts: 125
Joined: Sat Jan 27, 2007 1:55 pm

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ImageImageImage

Ive actually since had the valve cover and intake mani PC wrinkle red/black, cleaned up the wiring, and relocated the LS2 coils back onto the head, Ill see if I can find a pic.
It currently has:
Nistune installed
RB26 intake manifold/ITB's
some other small things but basically stock otherwise.

Plans are to:
Upgrade the turbo to HE351VE (manually controlled vanes for now)
TIG welded exhaust manifold (will build myself) :biggrin:


The build thread will consist of these upgrades and hopefully a successful tune/dyno.
Constructive criticism is welcomed, but keep all the other BS to your self please :)


Ive never welded in my life before. I bought an everlast 200LX off craigslist almost 2 years ago and it sat in the back of the shop collecting dust. I finally got it out, ordered supplies and started to weld! I was amazed that the machine actually worked, and was psyched to put down some welds after doing all the research beforehand.

Next post Im going to organize the pics I took of my welding practice thus far. Ill also post all the settings and details of what I used. The first practice bits are pretty rough, but Ill post them anyway so people can see what a complete novice (s***_ weld looks like haha

godzilla_753
Posts: 125
Joined: Sat Jan 27, 2007 1:55 pm

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Image
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Welding setup is:
Everlast 200LX TIG AC/DC inverter
CK WP 9 tig torch converted to #12 cup gas lens :chuckle:
3/32 lanthanated tungsten always ground to sharp point
100% argon
HF cart
Ebay auto darkening helmet
Filler rod currently is 1/16 308L for everything Ive welded, will probably switch to something smaller in diameter in the future.

mixeds14
Posts: 601
Joined: Tue Feb 26, 2008 12:44 pm
Car: 240
Location: nc

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Glad ur doing a build tread on the neo, there a few of us out there with this swap, some stock and some built but there's almost never a built tread about them.. Although the s1/2 rbs are similar to the neo, it has it's differences and that's what makes it interested IMHO... Looking forward to seen this and the ls coils, I'm wondering if u got them like mine or similar..

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TimTurboZ
Posts: 663
Joined: Mon Oct 06, 2008 8:59 pm
Car: 95 S14 w/RBXX... 65' Mustang GT
Location: Sacramento, CA

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how did you mount the coils back on the head? I bought a wire kit because I didnt like how mine were connected coil on plug and I want a forsure good connection when I go back to retune (also with nistune) plus I didn't make a proper bracket to secure the coils so for now wires were easier. I also have a NEO in my S14 so I wanted to check in

godzilla_753
Posts: 125
Joined: Sat Jan 27, 2007 1:55 pm

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I need to take some pics for everyone, I took the coils and just twisted the bracket on the factory truck coils a little so they could literally bolt up to the VC with no other mods. It looks clean, and Ill probably do something else down the road but for now they are solid and mounted, and fire properly. I think a custom bracket would honestly be the best option. I also had plug wires, and remote mounted the coils, but I was having issues with space so I just direct mounted like factory. Also I reused the factory RB coil boots, and just slid them over the LS2 coils.

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TimTurboZ
Posts: 663
Joined: Mon Oct 06, 2008 8:59 pm
Car: 95 S14 w/RBXX... 65' Mustang GT
Location: Sacramento, CA

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with a spring between the coil and sparkplug?

i also considered if twisting the tabs on the coils would make them bolt up easily to the VC seemed plausible when i had them there

godzilla_753
Posts: 125
Joined: Sat Jan 27, 2007 1:55 pm

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Update:

Been working on a ton of different things but finally got back to my project. heres the pic of how to mount the coils :
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godzilla_753
Posts: 125
Joined: Sat Jan 27, 2007 1:55 pm

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Starting working on the 6-1 collector. Not an easy task, 4-1 not so bad but the added pieces for the RB make the precision of your measurements that much more important. I did the best I could with what I had, should hold up fine for what Ill be using it for. :dblthumb:

Started with making the jig to hold the pipe in my chop saw.
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It was made with bits of stuff laying around, got the inspiration from a thread on honda-tech forums. If anyones interested I can point out the thread.

I then moved onto practicing with home depot PVC piping, easy and cheap way to dial in the jig.
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moved onto the next two to get me this:
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I was pretty happy with the fitup there.

At this point I was a third of the way there and felt like my jig was doing okay. Wish I would have practiced a bit more, would have saved me some grinding when I moved onto stainless. For those that are confused as to why I only practiced with making 4-1 collector, its because to get the 6-1, you just add 2 pieces in the middle and viola you get 6-1. You basically mark you index of 0, and then rotate 90 in both directions and make 2 more cuts, 3 cuts total gives you the middle piece.

godzilla_753
Posts: 125
Joined: Sat Jan 27, 2007 1:55 pm

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Moving on to stainless I started with prep, figured it would be easier now than later, and would make any markings I made clear and easy to read.

I started with cutting my sch 40 1.5" pipe into 6" lengths Image

Then I wire wheeled them to get the s*** off them, cant remember what its called, but is an important step prior to welding. A little bit of love game me this:
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At this point Im ready to start measuring out my angles. In a perfect world using a perfect cutting tool, you would mark 0 on the pipe, and then measure 90 degrees from there to make your second cut. Because this is reality, I measure to 93-4 degrees to make my second cut to account for blade deflection. Could have used a protractor, but had this angle finder laying around so used it to mark my angles on the pipe. Image

put the pipe in my jig and made a few cuts to get me this:
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As you can see came out alright except that each cut I made, near the end because of blade deflection the blade would basically curve away from the pipe and not cut straight down like its supposed to. This gave me a lot of grief trying to achieve fitup and wasnt apparent with the PVC pipe because the plastic was much much softer and gave me less deflection. If I had to do it again, I would use a different cutting method. This was quick, but left me lots to grind down, so didnt save me much time compared to using a slow cutting bandsaw. Also the chop saw left alot of s*** hanging off the edges that needed to be cleaned up before welding, I recommend you use a carbide tool or dremel to zip all that off to have nice clean edges.

Some more cutting and measuring, and cleaning up with the carbide gave me this:
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At this point the pieces have all been grinded down to get the best fitup I could manage. I decided to start tacking them together. For some reason the middle piece is much shorter then the adjoining pieces, I ended up having to chop down the length so that all 3 would be able to fit up nicely.

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Threw some good strong tacks on there to make sure they wouldnt come apart. This ended up pulling them closer on the outside, and causing gaps on the inside where they meet so will have to somehow squeeze them together to put a tack on the inside so they stay lined up for final welding. Hope to have them fully welded tomorrow. Unsure if I will be doing 1 pass or 2 to get full penetration.

godzilla_753
Posts: 125
Joined: Sat Jan 27, 2007 1:55 pm

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As a side note I got the old turbo off the engine and lined it up against my new turbo to compare
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Stock t28 vs HE351VE

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The business end where all the magic happens, this turbo should get me into the 500 range easily with extremely fast boost characteristics. Should be interesting to tune around the variable A/R.
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A little test to see where the turbo should sit
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The money shot!! :biggrin:

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