So, i'm welding up a new 4->2->1 exhaust for my duratec install (at some point).

I have a plan to get he pipe runs the way I want, but i am now thinking about the silencer.

I have access to a sheet roller/bender, so I can make a custom can (after all, it's only two caps, perforated tube (cheap from ebay) and acoustifil. From what I understand, length rather than girth matters (in just this instance ).

In the fury, the exhaust runs in the side pod, which basically has an internal profile of a quadrant, and it's quite a size. Rather than shoe-horn a 6" can in there, I was thinking of making a can that fits the quadrant shape, but then allowing 1.5" air-gap all round.

I would insulate the whole pod with the acoustic, aluminium foil, carbon foam backed stuff which absorbs sound as well as protects the pod (I've used this stuff before, not cheap but is the business).

Can anyone see why this shouldn't work, or is it a good idea bearing in mind I can bend the stainless to the shape I need.

My other exhaust plans are,
primary pipes: 1 7/8, minimum length 27"
secondary: 2 1/4 or 2 1/8 depending on availability. Length 12"
final pipe through can and out: 2.5"

Needless to say, i'm crowdsourcing design advice, so let me have your thoughts pls.

Sounds like a fair idea to me as the volume is key.

It's just the end caps that'll be tricky. How did you plan to do them?

Should work fine, as long as there is a reasonable thickness of wadding all the way around the tube. Bikes have all sorts of odd shaped silencers.

BTW width must be important to some extent, a very skinny silencer will have minimal wadding between the perforated tube the the outer tube and won't do a lot.

put the can shape through the sheet bender, and have a flat sheet profile cut for each cap.

Then either chop 1.5" off the end of the bent can to weld to the cap and welding it to the *outside* of the end cap. This will guarantee the cap will fit over the can, and then I will need to weld in a small spacer piece to complete it.

If I can't cut the can accurately to lop 1.5" off each end, I'll just take a 1.5" strip and bend it the same way as the sheet. Worst case is that I tack and form the cap-piece around the end cap with my trusty 2lb knockometer (ncb special / percussive force transduction instrument).

We also have a very good cad/cam place Yorkshire Profiles that I can email the plans to. If they can do me the bends at a sane price, I'll take it to them. Nice and quick and will make welding a breeze.

To be honest, if I get the exhaust design right, I'll offer to do it for other owners.

I'm planning to use 1mm think stainless, maybe 1.5 for longevity. Stainless tigs really nicely.

Here's a picture of My 4-2-1 Duratec exhaust let me know if you wouldlike any dims




[img]
Exhaust Fitted [/img]

[Edited on 29/3/12 by big-vee-twin]

very neat work - did you build it yourself?

quote:

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Originally posted by FuryRebuild
Needless to say, i'm crowdsourcing design advice, so let me have your thoughts pls.

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No my skills fall well short of fabrication, good with wires though!

Its was made by Quantum sports cars and they claim that they have had good track results using it.

@DavieP

Heh - that reminds me of the post a while back of the guy who threw his toys out of the pram for potentially being insulted.

I did wonder how my use of that word would go down. I stand chastised.

Sorry I was bored.

Does sound like a very good plan, I can't think why it wouldn't work.

Cheers
Davie

Do soms reading up on the basic physics. This link: http://books.google.nl/books?id=k02s1fo03ekC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false

Is useful, but in German. You are looking at a quarter lambda damper basically. This needs to be a certain length to be effective at certain frequencies.

Good luck!

quote:

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Originally posted by FuryRebuild
anyone see why this shouldn't work, or is it a good idea bearing in mind I can bend the stainless to the shape I need.

My other exhaust plans are,
primary pipes: 1 7/8, minimum length 27"
secondary: 2 1/4 or 2 1/8 depending on availability. Length 12"
final pipe through can and out: 2.5"

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Hi

I used several sources. Vizards pinto tuning book (200 bhp+ whether it's pinto or duratec needs similar flow planning). I also have another ford 4cl tuning book (can't remember which) which reckons a minimum of 27" primary. A mate who's chopped a few exhausts as well suggested 27" as well

Steve at sbdev.com so helped, but he makes a system of his own and was (understandable) restrained about the details. Saying that, he was willing to sell me plans at what I thought was sensible money. Not sure if I'll go for it yet or nail my own and experiment.

If I get it right on my own, it wouldn't be wrong to offer a custom build service to people.

Thanks for asking.