HX35 On stock RB25 Manifold No Cutting Just Some Welding

Discuss the RB20, RB25 and RB26 series engines.
opticnerv
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After some research and some mesurements I came up with a solution to mount up the HX35 onto the stock RB manifold with out cutting a hole for an external waste gate. Just to warn you the pictures you are about to see are pretty haggard, and the welding came out pretty ghetto so please don't flame it's all going to get done correctly and proffesionally the next time around.

This is it loosely mounted.

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Notice the wastegate flange is facing the compressor housing. ( I take %100 fault, but thats what I get for not double checking my self)

Note the s*** welds. I preheated and got pretty good penetration in some spots, but this is something I should definitely leave to a professional I will grind the welds off this weekend and send it out to get re-done.

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This is the adapter I used. I would have bolted it on to the Manifold but the wastegate adapter doesn't leave any space for a bolt or nut. When I take it apart I will show you guys what I mean.
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A picture of the car as it sits haha.
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Please let me know what you guys think. Remember I'm not a professional by any means. I'm also sending it out to get re-welded. So far it seems it will fit and work ( this was my main concern).
Last edited by opticnerv on Mon Sep 27, 2010 8:41 am, edited 1 time in total.


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ninety1two40
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I'm surprised it fits and doesn't hit the strut tower. This is my setup with a HX35:
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But it needed another 1/2" spacer to clear the compressor housing and manifold

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opticnerv
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Those are very nice welds, do you happen to live in the Tri-State area ? It does touch the shock tower slightly, I'm sure when I bolt everything down it won't. Even if it does I can grind some metal off the exhaust housing. I have the HX35w. The Internally gated HX's have a hump on them to mount the actuator, that's the only thing getting in the way.

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ninety1two40
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I had someone weld them for me, there is a certain way since the manifold is cast. Here's another picture with only one spacer. Yeah I live near Albany, NY though.

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ST240
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Lol. Look at my fitment:

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Thats also with a 1/2" spacer. I had to mash that silicone elbow in there. It's not as bad as it looks really...

Yo-jAn
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what size are the turbo youe using,i know there is a few different sizes out there, reason i ask is because im looking to upgrade pretty soon and want something responsive for drifting.
thanks
looks good btw

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ninety1two40
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I have the 12cm hot side and it's a bit laggy with my RB25, been only drifting a little on it, but alot of UK guys run them. I just need more practice. Full boost (15psi) around 4k, on a conservative street tune.

opticnerv
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Ninety1two40 I give you props for such a clean install. I'm in the process of cleaning everything up.

I drew this up last night.

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I hope my friend who owns a machine shop can hook it up with a good price this way there is absolutely no welding, onto cast iron. I have a question, would any waste gate smaller than 38 Millimeters be too small for the HX35 ?

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ninety1two40
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I have a 38mm wastegate with 15psi spring and I wouldnt go any smaller, boost creeps to 18psi on high gear pulls .

opticnerv
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You will notice in these drawings the bolt holes are expose by the 38 mm hole. I drew a red arrow and left the two holes highlighted in red. Do any of you guys think that if I bolt it this way the bolts I run through there will get effed up from all the heat ?
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ninety1two40
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I'd run the wastegate on the top of your adapter piece, there's plenty of room .

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jetdriver
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I made an adapter like that for a he351. I put the wastegate out the bottom between the block and turbo, but the compressor housing hits the frame rail!

240z4u
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opticnerv wrote:You will notice in these drawings the bolt holes are expose by the 38 mm hole. I drew a red arrow and left the two holes highlighted in red. Do any of you guys think that if I bolt it this way the bolts I run through there will get effed up from all the heat ?
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You will likely have problems with eroding the bolts that are exposed. I wouldn't do it.

The HE351 is freaking enormous.

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Sil240
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Why would you need a bolt running through your wastegate port??

I dont think you can find a EWG smaller than 38?

If I were you I would jusbore a hole in the mani then weld the wg flange on.

Or get the ATP ultimate internal wg.
I'm runing that right now very happy with it

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ninety1two40
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Sil240 wrote:Why would you need a bolt running through your wastegate port??

I dont think you can find a EWG smaller than 38?

If I were you I would jusbore a hole in the mani then weld the wg flange on.

Or get the ATP ultimate internal wg.
I'm runing that right now very happy with it
Thats how mine is, works great. But to hold the internal wastegate shut I bought a HX-35 outlet flange of ebay and it has a hole tapped to run a bolt through and hold the wastegate closed, been working great so far. I needed a flange anyway for my downpipe, you cant see the bolt but here's a pic:
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opticnerv
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Good call on the ATP Ultimate internal waste gate I'm checking it out now seems like a more simple solution and probably cheaper in my pocket !! :)

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ST240
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opticnerv wrote:Good call on the ATP Ultimate internal waste gate I'm checking it out now seems like a more simple solution and probably cheaper in my pocket !! :)
Yeah its great if you like serious boost creep. The thing is set at 6 psi and it runs at around 15. I'm putting on an external this winter.

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ninety1two40
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Yeah the size of the internal wastegate is kinda small for our applications. I recall you have to port the opening larger and it will still give you issues. I dont recommend anything smaller that a 38mm EWG, go larger if you can, I probably should of. My 38mm open dump is loud as hell too!

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Sil240
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I did port out my housing to about 28-29mm
I'm running 15 psi and I'm not having ANY problems at all overboosting.
But maybe to control little boost its not too good.

Why would you have one only running 6PSI?
Is there something wrong with your car?

I drove mine 16 hours to TOTD and 15 hours back.
Plus all the driving up there.
0 problems.

Also I'm running a Greddy Profec B Spec 2.
Maybe if you running a MBC you might have a problem, but you may have the same with a EWG.

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ST240
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I wanted to run a 6 psi gate so that I can tune it safely.

After all the feedback from other gasoline holset users and from what I've experienced, I've deemed the internal wastegate to be simply inadequate so it's hitting the whiskey bin regardless. MBCs by design should be reliable. But if I find I'm still having creep/overboost issues then yeah I'll switch to an EBC.

mixeds14
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opticnerv and ninety1two40 im interested on this mod yall did since all the manifold are expensive.. i can get my hands on an hx35 but had a few questions for yall.. what injectors are yall running n what are yall using to tune this...

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ninety1two40
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Top feed 780cc, with JGY rail, nismo fpr, walbro 255

Megasquirt II/extra ECU

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l0nestar
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ninety1two40,
I like your manifold.. I wish I had contemplated this before having mine coated. :facepalm:

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ninety1two40
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Thanks. I have about 4000 hard miles on it, no issues!

Here's a few miles:
http://vimeo.com/16837013

Darius
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Hey opticnerv, can you please enable PM's so I can respond to your message?

Thanks!

Mistaken
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ninety1two40 wrote:I had someone weld them for me, there is a certain way since the manifold is cast. Here's another picture with only one spacer. Yeah I live near Albany, NY though.
Random fact for those considering welding to their stock manifold. When welding to cast iron you should preheat the manifold first. Also you will need a special filler rod for tig welding, its softer then traditional fillers. If you don't preheat a lot of times the weld and material will cool at an extreme difference in rate and will crack the weld.

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l0nestar
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Mistaken wrote: Random fact for those considering welding to their stock manifold. When welding to cast iron you should preheat the manifold first. Also you will need a special filler rod for tig welding, its softer then traditional fillers. If you don't preheat a lot of times the weld and material will cool at an extreme difference in rate and will crack the weld.
I believe Ni-55 is the filler to use. It takes ~80-120A , and pre-heats to minimum 350*f (at least according to Inweld).

240z4u
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I have also heard that the metal used to cast these and most other nissan turbo manifolds are closer to regular old steel than cast iron. Yes, its a nickle filler rod that is used. I have had a few nissan exhaust manifolds welded and they all turned out beautifully.

opticnerv
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Switched up my design a little bit
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ninety1two40
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Nice, that makes more sense now ha. I'd recommend a v-band wastegate if you can swing it.


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