Cobra.au Side Pipe Build

[Cobra.au]

Hi guy's
I thought I might start a thread on the construction of my side pipes as it seems a pretty hot topic at the moment.

I will up date with pic's as the pipes go through the build process I should have most of the components by the end of the week but to give you an over view the material list is as follows keeping in mind they are designed for my supercharged 408 stroker

2" primaries
3 1/2 collector
4 1/2" outer shell
4" high flow metal cats (200 cell)
3" straight through perforated tube

here are the flanges I milled up from 10mm snow ground plate


Here are a couple of pic's of the Cats


And a look inside


Stay tuned for more info

[Churchy]

Craig,

I will be very intertested in the progress of this as I am just about to embark on that exact process. Any tips or pointers you can share would be great.

Cheers

[Tenrocca]

I think a lot of people will find this thread helpful - thanks Craig. Are you going stainless?

[Cobra.au]

I will be making the primaries out of steel as this is the most heat effected part of the system and from the collector back out of 316 stainless because try sourcing 4 1/2" tube in any type of material. I was just lucky to know a guy who knows a guy who had a mill run of this odd size done and it was perfect to slip a 4" cat into with an air gap so there will be no discoloration later on from heat.

Once the pipes are finished they will be Jet Hot coated.

Stay Tuned

[spookypt]

Craig..you're forgetting 1 important thing! EAR PLUGS.... I have just modded mine to make it more streetable. Cats are now in (phew BIG fine otherwise) and choke cable operated butterflies that I can yank if the police pull up next to me at the lights...

[Cobra.au]

Spookypt
I am currently running side pipes that are 2.5" perf tube with no packing, the cat converters left the building along time ago and the slip fit joints suck in so much air that when you back of from high rev's and the extra fuel from being on boost it back fires shoots a big ass flame out the exhausts everyone with in a 100m radius hits the deck thinking that the terrorists have finally struck and if your lucky a nearby car alarm will go off and then I try to idle away pretending it wasn't me.

So I think no matter how I build my new pipes they will be quieter.

PS. The last time i was pulled over by the police (followed me for about 5K taking it easy) they didn't stop me for the noise they stopped me because they thought my front number plate was on to much of an angle.
Go figure?

[Ralph_C]

Originally Posted by Cobra.au

PS. The last time i was pulled over by the police (followed me for about 5K) they didn't stop me for the noise they stopped me because they thought my front number plate was on to much of an angle.
Go figure?

And they decided this while following you?

[Cobra.au]

NO

They were behind me
Then they pulled along side me (duel lanes)
Then they were in front of me (in the other lane)
Then they droped back beside me
Then they pulled back in behind me
Then they turned on their lights & siren

Hope it is clearer for you now

[Cobra.au]

Here is a pic of the type of merge collector that we will be making inhouse

[snkbte]

Originally Posted by spookypt

Craig..you're forgetting 1 important thing! EAR PLUGS.... I have just modded mine to make it more streetable. Cats are now in (phew BIG fine otherwise) and choke cable operated butterflies that I can yank if the police pull up next to me at the lights...

Spookypt, I’m interested in the BUTTERFLIES you have installed. I was under the impression that they would be of little effect and greatly disrupt engine management by varying back pressure. Where in the system have you installed them and if you can, photos please.

SNKBTE

[Gav]

Craig,
Your collectors alone make my pipes look like the povo version

[Cobra.au]

Gav
Things are always easier the second time around, well thats the theory anyhow
The two main reasons I decided to make another set of side pipes are

1. I really hate slip joints as they nearly always leak

2. No one seems to have designed a side pipe with hi flow internal cats (its surprising how poor standard cats flow)that are the right distance along the exhaust so they actual work.

The only other hi flow side pipes I have seen had the cats mounted in the inner guards before the pipes exited out of the side of the car the big draw back of this is the reduce primary length which will rob you of low down torque.

[Gav]

Yes,
I would have to agree about the second time round thing.
I have now completed assembling the passenger side of my pipes and already can see how I could have made life easier if only my crystal ball wasn't so dirty!!
I am counting on the muffling effects of the cats to hopefully drop a few Db's from the note. The flow isn't such a huge issue for me with the relatively low output of my combo (275 Kw).
The primary length thing is in the bag though, around 1000mm surely is enough!!

Gav

[Aussie Mike]

Nice collectors I reckon like they turn out very nice going by the standard of your other engineering.

You can buy 4 1/2" mild steel tube and larger sizes through Aero engineering in Tulamarine Vic.

I'll watch this build with interest having built a few sets of pipes myself.

The Cats in mine aren't metal Cats but they are suposed to be Hi-Flo. Phil used my design and these cats didn't seem to hold it back as he made 243 RWKW on a standard unopened motor.

Cheers

[Cobra.au]

Gav
A primary length of 36" (1m) seems the norm these days.

Mike
The main reason I am focused on flow through my system is once I pulley up my Vortech and find a few extra cubes I defiantly wont have problems getting air in and through the engine I want to be happy that it is not getting held up on the way out.

I will start making the jig for the merge collectors tomorrow so from this week on it will be full steam ahead

[Aussie Mike]

Fair enough, with that blower turned up you'll be pushing a lot of volume through. You'll need all the flow you can get.

Any idea if the metal cats run hotter or cooler than a conventional cat? You often see them without heat shields attached so I thought they might run cooler.

Cheers

[Aussie Mike]

I wana know how they weld up the inside of those merge collectors. They look like they are made from 4x 45degree bends that have been grafted together. I reckon there must be some tricky way they make them to get the insides so nice.

I did mine by welding up a steel pyramid shape into the merge section made from triangular sections of tube. I weld them together along their edges and then sharpen up the welded edge with a die grinder.



The pressed 3 1/2" collector tube then slips over the whole thing and gets welded in place. Not as pretty looking but a lot easier to make.



Keep us posted.

Cheers

[Jerry Clayton]

Mike--They use varied amounts of bend to build the merge-20 degrees looks good in 2in tube-the degree of bend varies with the size of tube vs collector diameter. You can cut up some bananas or cucumbers to get the idea of the merge-

There is a company down the street from us that we do work for that makes up rolled tube out of stainless into any diameter you want and seam welds it. they can do tubes around ten feet but shipping is very high if it is 5 ft or over it becomes an oversized package( UPS ) I'll ask if they would ship down there and if they have a web site

Jerry

[Jerry Clayton]

Try WWW.techweld.net/

They are in Elburn Illinois and tell them I sent you

Jerry

[Cobra.au]

My fabricator told me that its not a problem to do I will get the pipe pre bent then he will work out the profile to cut with the plasma and then it should all fit together sounds easy when he said it, also I will need to buy him a straight tig torch to weld it all together internally.

I will take plenty of pictures as we go so you can see the process involved