16V Syncro manifold building

Discussion in 'Engines' started by Trev16v, May 23, 2011.

  1. Trev16v

    Trev16v Paid Member Paid Member

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    See what you mean. It's odd because as far as I'm concerned a downpipe that lets you fit a 16V into a Syncro with the Scirocco manifold is something you would absolutely have to make yourself. But I can't see any signs of welding on that. Bizarre. I'd be curious to know more. I posted on VWSyncro.co.uk about it.

    I'll keep hold of my Scirocco manifold and do this as a Plan B if the Limited manifold copy idea goes tits up!
     
  2. Trev16v

    Trev16v Paid Member Paid Member

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    Progress so far:

    I ordered a load of Schedule 10 stainless steel (316L) 90 degree bends from All Stainless. I also ordered a matching offcut (700mm) of straight length 316L tube.

    The 316L stainless, 12mm thick 16V head and downpipe flanges are in the process of being water cut and I hope to have them within a week or two.

    This weekend I assembled a simple jig to enable accurate marking of a cut line on the 90 degree tubes, so that a cut line of any angle can be drawn while keeping it on the correct radius (erm, you know what I mean) so that it's a perfect cut. I'll stick up some pictures of that in use in due course. I also formed a guide ring that tightly slips over the tube after it has been marked to act as a guide for when using the 1mm grinding disc when cutting the tube, because my initial attempts at holding the angle grinder steady enough were pathetic. The end result is a pretty damn accurate and nice cut on the tubular bends. The cut tubes mate with each other nicely and are ready for TIG welding almost immediately without much need to fettle with them. I just de-burr them, and bevel the end of the pipe using the bench grinder to form a ridge to weld into.

    After feeling reasonably confident at welding stainless (my initial attempts were sh*te as I had not touched the TIG for ages, but got okay eventually) I had a go at welding together a schedule 10 bend that I have cut up for practice, and I was really pleased with the result. The welds come up lovely after scrubbing with a stainless toothbrush. It's not that pretty yet, but I feel almost confident enough about the welding to start making the real manifold.

    A problem with welding stainless is that the back of the weld (root) looks sh*te; ideally you need to purge with argon inside the tubes when welding stainless tubes together. I didn't really take much notice of all the talk about purging until I had a go at welding stainless for myself and saw how ugly the reverse side of the weld is; it really does 'sugar' horribly. I really hate the idea of messing about with purging though because TIG welding goes through argon pretty fast as it is, and it's a PITA getting the bottle refilled. So, I'm thinking of buying a tin of something called Solar Flux (type B for Stainless), which is a US-made tin of powder that you mix into a paste and apply to the inside of the stainless tubes around the weld area. It's an alternative to purging and apparently works really well. It is known to leave a very tough glassy residue on the inside of the manifold around the welded joints, which could in theory eventually cause debris which might be a problem for tubo applications, but my manifold is for N/A and I don't even have a cat to worry about either. Has anyone on here used Solar Flux?
     
  3. MUSHY 16V

    MUSHY 16V Moderator Staff Member Moderator

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    you dont need a lot of argon to back purge it
    tape of the ends with masking tape and round your argon pipe
    then prick the tape other end from the pipe with the tungsten so you have a small hole 3 to 5mm
    then purgde it till you feel it for a few seconds to let the air out
    you can get a purge monitor to check it but thats a bit of overkill of you

    then weld for a bit then purge it again you will soon find out how long you can weld for
    it can be better to doing it this way
     
  4. Trev16v

    Trev16v Paid Member Paid Member

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    Okay mate, perhaps I'll have a go at purging.

    A can of the Solar Flux stuff will be somewhere between 50 to 70 to buy, so is expensive stuff, but does apparently go a long way. However considering how much stainless fabrication I'm likely to be doing (not much!) I guess an extra argon refill cost, plus the cost of a Y-piece and second flowmeter for the separate purge supply is going to work out pretty much the same.
     
  5. sambo Paid Member Paid Member

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    Can we have some pics please Trev? I love diy manifolds :)

    Reason why i used heavier sh40 is because i wanted extra strength to support weight of the turbo and preffered snaller ID of the sh40 then sh10 to improve spool of the turbo

    Stuff you bought will be more then adequate for NA application

    Looking forward to updates on this thread
     
  6. Trev16v

    Trev16v Paid Member Paid Member

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    Thanks Sambo. Will be sure to get some photos up shortly.

    My 316L stainless flanges were designed by my mate Alan and were water cut for about 100. They look very nice.

    A while back, Bugwhizz over on Dubforce showed images of a similar manifold he had made. What's interesting is the way it has been constructed so that the main tubes route to opposite downpipe tubes compared to the standard cast manifolds. This gives a longer runner to the collector to those two inner ports, and keeps the lengths more equal. This is a more complicated manifold to fabricate though.

    Here's his manifold:

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    Any thoughts please? As it's my first manifold project I am tempted to keep it straightforward and basically copy the VWMS manifold. Also, I guess one would need to perform some RR comparison before being able to definitively say that any design is better over the other.
     
  7. Trev16v

    Trev16v Paid Member Paid Member

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    I have noticed now that the G60 Syncro downpipes' lengths are slightly unequal as if to compensate. The downpipe that's nearest to the engine, that mates to the shorter inner runners on the cast manifold, has a slightly longer run where it angles below the bulkhead. Obviously I know next to FA about exhaust design (can't you tell!) but to me it looks like VW designed the downpipe with the cast manifold so that there are equal lengths between the head ports and where it eventually collects way far back at the cats (or cat bypass in this case).

    Just gonna copy the VWMS item as it is I think.
     
  8. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    I already know after spending lots of time and money with Ben S that the between factory cast, VWMS/OEM 220PS and VWMS 260PS manifolds, on a nominal NASP car with an adjustable ECU, the above component/Mapping swap made very little difference.
    Your boosted 16v engine may benefit as there is more flow and exahaust energy. However you would need to test the engine in a fully mapped state on the cast and then the tubular component, again on a mature calibration in order to determine if there is any benefit in an A-B experiement.
     
  9. Trev16v

    Trev16v Paid Member Paid Member

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    Thanks Ed, that input is much appreciated.

    Well, I've made mega progress with this over the last few weeks. I've got most of the tubing cut and I've started to tack it all together. Will start getting some images up.
     
  10. Trev16v

    Trev16v Paid Member Paid Member

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    Okay, picture updates. To start with, I needed to make a jig that would position the downpipe flange where it should be on the back of a 16V engine. To do this, I made the jig so that it mounts securely onto the rear engine mount threads on the PG G60 engine and G60 Syncro exhaust manifold. Then, this jig is bolted to the back of a 16V engine. I'm absolutely confident that the rear engine mount lugs are a perfectly good datum point to use between engine blocks - please shout very loudly if you think I've not considered something!

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    My friend Alan Lawrence designed the flanges for me. These were then water jet cut out of 12mm 316L stainless by Waterjet Precision UK Ltd (www.cncwaterjet.co.uk).

    All Schedule 10 pipe fittings and a length of straight (all 316L stainless) were obtained from http://www.allstainlessltd.co.uk/.

    I did order some Solar Flux after all. Got it very well priced from PCES. I've not actually used this yet as I've not got past the tacking together stage.

    [​IMG]

    I arranged this setup to enable me to mark a perfectly true radius cut on the pipe fittings.

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    These are the 1mm cutting discs I'm using. They're bloody excellent. Even after cutting all of the tubes I've done so far (to get to the stage I'm at pictured below) I'm still on the first disc, which has only reduced in radius by a few mm.

    [​IMG]

    So far:

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    [​IMG]
     
  11. alexisblades99 Forum Member

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    This looks like it's coming together really well, good idea with the wooden jig too.

    It looks like the bolt holes in the flange are a little bigger than they need to be, which would be good, as I would guess this is to avoid the studs shearing when the stainless expands at a different rate to the head. I have noticed other manifolds often have some of the bolt holes too big, I suppose to avoid the same problem. Either that or they have thin vertical slits cut in the flange between the ports to allow a little movement, and avoid shear stress.
     
  12. Trev16v

    Trev16v Paid Member Paid Member

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    Ah yep - he oversized all of the bolt holes except two of them. So two of them locate the flange and the remaining ones allow for expansion. I think this is standard practice, and the OEM cast manifolds are like this too.
     
  13. Trev16v

    Trev16v Paid Member Paid Member

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    Got a few carbide tungsten burrs off eBay to use in the die grinder now. Obviously the cheap bits that came with the much-cheapness 15 air die grinder last about two minutes on stainless steel!

    Also loads of G-clamps to clamp the flanges to some really thick metal when welding on them, to try to limit warp. Anyone have any tips on that? I thought I'd use a scrap 16V head as a big heatsink for the head flange.
     
  14. Trev16v

    Trev16v Paid Member Paid Member

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    Latest progress.

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    Reasonably pleased with this as it's the trickiest part done, and I had it G-clamped up to a stupidly thick slab of steel (the large thick steel plate that belongs to my press, in fact) so the amount of warp on the downpipe flange is very minimal. It might be alright as it is without skimming it.

    The crud you can just about see on the inside of the tubes is the Solar Flux residue waiting to be cleaned away. That stuff works really well.

    My TIG welding isn't winning any prizes yet; there are some particularly nice sections I'm pleased with but I need a lot more practice to get it consistent.

    I still have a slight problem in that there's about half an inch of circumference around where one of the collectors mounts to the flange where I can't get into to weld. I did know beforehand that this was going to be a problem but I couldn't see any other way I could assemble it all to avoid that happening. I thought I would be able to really stick out the tungsten and really crank up the argon, but no. So I think I need to get a gas lens. Apparently they allow the tungsten to protrude by up to 2cm. Alternatively I'm going to have to use the tungsten carbide burr in the die grinder to take a bit of material out of the port hole in the flange so I can weld the base of the tube from the inside as well.
     
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  15. 1990

    1990 Paid Member Paid Member

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    That looks great Trev!! Cant wait for you to do my 6cylinder one!!
     
  16. Trev16v

    Trev16v Paid Member Paid Member

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    I'd be quite happy to weld it up if you cut and jig the tubing and drove down with it! Bring your mum :thumbup:
     
  17. sambo Paid Member Paid Member

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    Very good Trev, looks like you were very technical and paid alot of attention to angles etc
     
  18. scruffydubber Paid Member Paid Member

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    Great work Trev.
    Hope your making two[:$]
     
  19. Trev16v

    Trev16v Paid Member Paid Member

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    Cheers both (not ignoring your message on FB Gareth mate - will get in touch!)

    Few more pictures from last night when I very nearly completed it. Just have a couple of areas to fill in still. (Excuse the shonky phone images.)

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    IMAG0707 by Trev16v, on Flickr

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    IMAG0714 by Trev16v, on Flickr

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    IMAG0719 by Trev16v, on Flickr

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    IMAG0710 by Trev16v, on Flickr


    ...which compares to the original Holy Grail:

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  20. Trev16v

    Trev16v Paid Member Paid Member

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