Volumex 4-1 header build - Design, fabricate, feedback

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037_beta
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Volumex 4-1 header build - Design, fabricate, feedback

Post by 037_beta »

Over the last few months I have been slowly building a set of big bore (41mm OD) equal length (36 inches) exhaust headers for my 1800 Volumex project. The system as it stands today is my "test fit" system built from mild steel mandrel bends and minus the merge collector. The final exhaust headers will be built from 304 stainless once I have it all worked out. I have tried to ensure that no bends are greater than 45 degrees to cut down on any potential for back pressure. The system as you see it here is in no way final and will never be run on the car. It is merely to work out all the bends, details and test fit before I get too serious with 304 stainless.

Given this is almost to the stage of being the final mock up are there any comments from Guy or members on the overall design? I hope that this post can serve as a helper post to anyone else heading down this path. A big thanks to Guy for his assistance in getting me started with ideas and specifications for the system. There were no "off the shelf" options that I could find which necessitated an entire "scratch built" system.

Note: The head and block seen in the photos are old "junk" parts and not part of the in-process build. They serve as a useful jig in the mock up.

This is the original 4-2-1 system that fits nicely on the car. I have used this to model a wooden buck/jig to ensure the pipes are not too long, or too high under the car. I have found that this is a good way to ensure that the bends are all in the right place.
Original 4-2-1 system used to build a "buck" to model the position of the pipes of the new headers.
Original 4-2-1 system used to build a "buck" to model the position of the pipes of the new headers.
IMG_2871.jpg (60.18 KiB) Viewed 13479 times
Next, I purchased some plastic flexi-pipe from the local hardware store to help determine what mandrel beds to purchase. This was a good visual reference to help picture how the end system needs to look. It is also good for working out variations on the beds of each pipe.
Plastic flexi plumbing pipes to mock up the system to work out the required bends.
Plastic flexi plumbing pipes to mock up the system to work out the required bends.
IMG_2878.jpg (48.15 KiB) Viewed 13479 times
I purchased an exhaust flange that needed a fair amount of cleaning up with the die grinder and sander before it was ready to use.
Exhaust flange - I was lucky to find this.
Exhaust flange - I was lucky to find this.
IMG_2860.jpg (34.33 KiB) Viewed 13479 times
I started out fitting and tack welding (TIG) the rear pipe for number 1 cylinder.
The first bends clamped in mock form
The first bends clamped in mock form
first_bends_in_place.jpg (69.24 KiB) Viewed 13479 times
The next piece of the puzzle was the long task of cutting, grinding and fitting the bends into place. This is the work in progress.
First tacked bends in place
First tacked bends in place
building_headers.jpg (70.34 KiB) Viewed 13479 times
This is a different view of the work in progress. It is quite an arduous time consuming task to match all the bends, clamp and tack weld. I am no master fabricator by any means.
A different view of the work in progress
A different view of the work in progress
building_headers_2.jpg (50.53 KiB) Viewed 13479 times
This is where the build currently sits.
Where things are at now minus the merge collector.
Where things are at now minus the merge collector.
building_headers_3.jpg (42.25 KiB) Viewed 13479 times
The pipes are equal lengths and only need some minor trimming (and extending to 36 inches) before being ready for the 4-1 merge collector.
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Guy Croft
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Re: Volumex 4-1 header build - Design, fabricate, feedback

Post by Guy Croft »

Good work Anthony, always nice to see someone 'having a go' and learning new skills, esp if the concept is in line with GC recommendations as it is in this case.

Not a million miles removed from a 4-1 header I had made some years ago. It has a 'flat-plane' collector, obviously for clearance reasons.

G
Attachments
not a great photo, had a couple made by a UK firm till their quality & customer service got so poor I could no longer recommend them. Note the flexi-pipe which is vital on FWD systems..
not a great photo, had a couple made by a UK firm till their quality & customer service got so poor I could no longer recommend them. Note the flexi-pipe which is vital on FWD systems..
Lancia 4-1.JPG (25.3 KiB) Viewed 13427 times
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tricky
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Re: Volumex 4-1 header build - Design, fabricate, feedback

Post by tricky »

Looking nice, when you get to the final thing it's well worth the effort to perfect each joint as you go ie; cut perfectly on tangent and square to the tube it mates to. I found you cannot miss one and come back to it later to get it right as it throws the whole thing out further down the line.

One other thing that makes the finished article look very professional is to buy bends with as much 'leg length' as possible, which saves un-needed weld joints.
Twice as many valves
037_beta
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Re: Volumex 4-1 header build - Design, fabricate, feedback

Post by 037_beta »

Thank you for the comment Guy. It has certainly been a learning experience to this point. I have the photo of your exhaust pinned to the wall in my garage as a reference point. I will be posting back here when I complete the stainless system.

Tricky, I completely agree with your comment on the leg length. It certainly makes things a lot easier and nicer looking to use the legs where possible. Even though the bends are "mandrel bends", they always still have necking (at least 1mm but usually closer to 2 to 3mm) throughout the bend radius. This makes the fit-up and tacking a nightmare. Using bend legs is a good way to avoid this but sometimes the bend radius does not match perfectly so one has to cut, clamp and fabricate.
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037_beta
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Re: Volumex 4-1 header build - Design, fabricate, feedback

Post by 037_beta »

Over the last few days I have built two jigs to assist with the fabrication of the primaries in stainless steel. Each jig has taken me roughly 5 hours to fabricate. The photos below may help others that are considering fabricating a stainless header system. In one of my fabrication books by renown metal worker Ron Fournier, he states: "If you do not think headers are difficult to fabricate, you will after you have built a set". The real issue with fabricating headers is just how much preparation work is needed to get mandrel bends to match up flush. Then there are the associated issues with mandrel bend necking and even holding the non-magnetic pipes in place to tack weld. A while back I saw a video on Youtube (I will post if Guy agrees) that demonstrated a clamping technique that I have utilized. The main difference between the system in the video and my system is that I can adjust mine after tacking. This clamp system is extremely useful in the fit-up and even the mocking stage. With the bends clamped one can then hold the system against the head to view how it looks in terms of the general pipe layout and all before even laying a single tack weld.

Please note that I was a bit rushed with the photos and did not get all the bends clamped and lined up before photographing. I have also added additional clamps and every bend now mates flush.
Another pair of hands is extremely helpful.
Another pair of hands is extremely helpful.
resized_fitup_jig_3.jpg (65.35 KiB) Viewed 13226 times
The pipe I am duplicating vs the jig.
The pipe I am duplicating vs the jig.
resized_fitup_jig_2.jpg (67.08 KiB) Viewed 13226 times
The jig up against the head for visual referencing.
The jig up against the head for visual referencing.
resized_fitup_jig_1.jpg (72.36 KiB) Viewed 13226 times
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Guy Croft
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Re: Volumex 4-1 header build - Design, fabricate, feedback

Post by Guy Croft »

MODEL POST!

I am very impressed.

Sure post the link to Youtube!

G
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037_beta
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Re: Volumex 4-1 header build - Design, fabricate, feedback

Post by 037_beta »

Thank you Guy for the kind words.

The video I mentioned is part of a high quality series on Youtube that runs the viewer through an exhaust header build from a mockup in PVC piping right through to welding the bends. I found the series very informative and to be honest I have not come across anything like it outside of Ron Covells metal working DVDs. Part 3 covers the header fabrication jig which served as a strong influence on the design of my jig. Part 3 of the aforementioned video series can be found here http://www.youtube.com/watch?v=Bc-KhMl-6ss.
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037_beta
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Re: Volumex 4-1 header build - Design, fabricate, feedback

Post by 037_beta »

I recently had two inquiries querying where one can purchase exhaust header flanges. The most reliable source is the team at Columbia River Mandrel Bends. With Guy's permission their web address (that will land you on the header flange page) is: http://www.mandrel-bends.com/catalog/fl ... /Fiat-210/

I have purchased quite a few bends, bungs and flanges through "Columbia River" and their service has always been good. They make the flanges to order out of either mild steel or 304 stainless. They can also provide two different thicknesses with the thickest being 1/2 inch.

My next update will document the current progress on the exhaust. It has been some time since my last post and the system in 304 stainless is now tacked together. It has been a somewhat slow process over the last few months. I spent the best part of a month waiting on a new pyrex large diameter TIG gas lens to ensure full gas coverage, and also tried a few different "trailing purge" setups to keep colour in the welds. I am now waiting on a small sewing machine motor (with foot pedal) as it is the basis for DIY weld positioner. Stay tuned as there is more to come.
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Guy Croft
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Re: Volumex 4-1 header build - Design, fabricate, feedback

Post by Guy Croft »

Fabulous top pro stuff - keep it coming and keep it here!!!

G
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fingers99
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Re: Volumex 4-1 header build - Design, fabricate, feedback

Post by fingers99 »

Great post -- extremely informative.

Apropos the -- albeit slight -- necking down of mandrel bends, I'm pretty sure this could be mostly eliminated given the right facilities, lots of time and effort, and one's own bending machine!

Another approach (and this touches on someone's post on hydroformed exhaust systems) might be to hydroform the pipes from 2 peices of flat steel (relatively easily done with a CAD operated water jet or even plasma) welded together. Of course, given this relatively easy approach, without formers, you could only achieve 2 dimensional bends in any given section.

By the way, you might like to try running a simple purge line through the inside of the pipe. Take off would be from a T fitting and extra flow gauge after the regulator. Bung can be made from crumpled up aluminium foil, exhaust (unless you're using Helium!) should be constricted (same or slightly larger tube than the inlet) and below the level of the inlet. On stainless, it should make for a better quality weld.
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Doug Brown
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Re: Volumex 4-1 header build - Design, fabricate, feedback

Post by Doug Brown »

Thank you for the informaton about Columbia River Bending and the Fiat 124 exhaust flanges they make!

You saved me a ton of money and time - now I don't have to one off them.

I'm going to be making a set of 4 into 1 mild steel headers for my friends Fiat Abarth 1600 OT clone and have been chasing down all the bits and pieces - and this was the missing link.

Thanks again,

Doug Brown
Guy Croft
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Re: Volumex 4-1 header build - Design, fabricate, feedback

Post by Guy Croft »

Hi Doug

kind of you to check in and say that!

G
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037_beta
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Re: Volumex 4-1 header build - Design, fabricate, feedback

Post by 037_beta »

Guy Croft wrote: kind of you to check in and say that!
That it was. Thanks Doug! Glad to be of assistance.

Some of the GC members might be wondering what happened to my project. I have been quite busy over the last year. Work has me flat out and these hobbies also have me flat out on the weekends. I have not finished off the headers, but I have tacked the 304 Stainless set together. (note to fingers99: I run a DIY back purge when welding stainless tube/pipe.).

Here is a final check before running the tacks on my jig:
checking_prior_to_tacking.jpg
checking_prior_to_tacking.jpg (56.34 KiB) Viewed 11806 times
Here are the Stainless headers as they sit all tacked:
stainless_headers.jpg
stainless_headers.jpg (65.39 KiB) Viewed 11806 times
I mentioned I was working on a weld positioner to ensure uniform welds. My workings were rough so I could see how to mount the pipes as a proof of concept. I use a ball bearing welded to a steel rod. Using this mechanism I can always center the pipe over the rotary tables bore regardless of the bend being welded.

This is where I got to before my milling machine arrived:
diy_positioner_workings.jpg
diy_positioner_workings.jpg (77 KiB) Viewed 11806 times
I have run into some minor distractions however that have stood in the way of my build. Firstly, I am building an 1800 Volumex which means that the standard cast iron Volumex mount is too tall. No wanting to hatchet something together (unfortunately I am capable of this!), I wanted to build a nice mount. I decided a sand cast aluminum mount would be best. I then decided a wax proof would be best to modify to suit the Volumex. Mid way through this process, I got very lucky and was offered a Lancia Delta S4 Volumetrico supercharger. Something I had been hunting for a long time. Not to worry, my mount was modifiable. About 20 casts later I have a mount that now fits 1800 and my Volumetrico. (I will post the complete mount building in a new thread at a later date as it is quite involved).

The wax cast mount. Better photos in a separate thread (if there is interest in this).
wax_cast_mount.jpg
wax_cast_mount.jpg (33.91 KiB) Viewed 11806 times
I was offered a Lancia Delta Integrale head and as always my curiosity got the better of me. I had previously read about the 16v reverse port cam swap that Guy had kindly documented (Carlos). There was not a complete profile on exactly how this was achieved. There were however encouraging words from Guy saying it was not overly difficult. With my new milling machine at hand, I was game for it. The day the head arrived I milled out some reliefs and voila! The cams can be flipped and the reverse port issue is solved.. It took me longer to make the angle plates to mount the head to the table, than it did to mill the mere 2 reliefs necessary!
(I intend on documenting this in full for the members - I am however reluctant to offer advice on it as I have no idea on the durability).
delta_integrale_head.jpg
delta_integrale_head.jpg (72.22 KiB) Viewed 11806 times
Anyway, they are my excuses for my project backlog. Each item above could have it's own thread. I intend on creating one for each item, but have yet to find the time. The Volumetrico is a particularly interesting story. I will leave this thread with a parting photo of my build from a few months back. It also puts the size of the Volumetrico into perspective.
build_currently.jpg
build_currently.jpg (40.51 KiB) Viewed 11806 times
I will be posting the completed headers, but this will be some time away as my weld positioner project is on hold until I complete the CNC conversion of my milling machine. By the time the weld positioner is done, I may well be showing the members here a completed set of 16v headers!
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fingers99
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Re: Volumex 4-1 header build - Design, fabricate, feedback

Post by fingers99 »

Each item above could have it's own thread
Or, if you find the time, you could ePublish a book. It'd find a place on my bookshelf along with the Fournier books and Guy's new one.

Inspirational stuff!
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Guy Croft
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Re: Volumex 4-1 header build - Design, fabricate, feedback

Post by Guy Croft »

AGREED!

so many gifted folk here, don't think they quite realise!!!

G
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