Legal sidepipes......

[hogster]

I know this question has been done but I am chasing some noise legal formulas for the muffler setup.....

The setup so far is 347 windsor, 1 3/4' pipes into 4 into 1 merge collector, flaring out to 3 1/2.

I will run cats inserted into the outlets of the merge collector.

The hard part is whether to try and build my own muffler or try a 'bolt on'.

Anyone who is actually running legal pipes, or had legal pipes, what muffler setup did you use?

I was thinking a repackable spiral baffle like in Alfie's gallery, packed with stainless steel wool and with the cats might do it??

Just ordered my merge collectors from Burns Stainless

Cheers

Hogster

[macloft]

Hogster dont you still face a problem with the exhaust exiting before the rear wheel on the passenger side and pointing at the footpath. In Queensland I thought this was illegal as well as the noise factor.
Bruce

[hogster]

Most of the Territory builders are able to get approval to run live pipes......real ones

When I wrote my application to build, and spoke to one of the committee members that approve these type of things, he agreed with me......."if it hasn't got working sidepipes, I don't want one"

[Plums]

Hogster, inside my pipes I run a cat and hotdog. It's pretty noisy but sounds "like it should sound for the way it looks". You can check my gallery to see how I've done it.
The way I have done mine is completely modular, so you can change bits around, remove the cats (or add extra cats for more quietening), or add longer hotdogs, whatever....

[400TT]

Yeah, the ADR basically specifies that exhaust gas cannot exit to passenger side of any vehicle. So even if you have an exhaust that exits out the rear but with a slight twist to the passenger side, it is still not compliant. Jap imports sometimes have this and need to be modified.

But the states can provide an exemption if they want. WA does this.

[hogster]

400TT - the ADR exemption is what the NT boys are allowing us to do...working sidepipes both sides.

PLUMS - What size outer pipe are you running to get over the cats - and where did you get the cats that size?? Are you just clamping it all together inside your outer cover?

Thanks

[Plums]

My sidepipes step up from 3.5" at the collector to 4" for the main body of the sidepipe, then back down to 3.5" at the exit.

The cats are 3.5" OD (as are the hotdogs) and came from an exhaust wholesaler here in Perth. I had to get him to order them in though, but I think he did get a bunch of them at that time.

[400TT]

Originally Posted by hogster

400TT - the ADR exemption is what the NT boys are allowing us to do...working sidepipes both sides.

That's fantastic.

Wish I could help with the side pipe information, but there are much more qualified people here to provide advice.

[macloft]

Sorry Hogster I thought you were Qld I now see you are NT. You lucky bugger. You are right A cobra has to have working side pipes.
How can we do this in Qld. I will bring some back from US with me.
Bruce

[Heidelberg]

Hi Hogster,

Being in WA, I wanted to have live sidepipes but I also wanted to get as much protection as I could against the nasty burns you can get from live sidepipes...

My solution was to get a ceramic coated 3 inch exhaust system fabricated from the headers back including a couple of small cats located just before the 3 inch pipe exits the engine bay. Having the cats located just before the exhaust pipe exists the engine bay gave us plenty of length in the actual sidepipe to fit a long hotdog "muffler" that reduced the decibles "enough" and gave the exhaust a nice note.

I then had a 4 inch (also ceramic coated) outer shell fabricated that totally surrounds the 3 inch exhaust pipe starting at the point the exhaust exit's the engine bay...This outershell is actually a heatsheild, but looks exactly the same as a 4' inch sidepipe. I also have heat insulation material in between the 3 inch exhaust pipe and the 4 inch exhaust sheild.

I'm very happy with the results...the pipes look like 4 inch sidepipes and whilst they still get hot, they don't get hot enough to really burn you!

The only downside with this design in my opinion is that you do not get the "4 into one look" at the start of the sidepipes....

Regards....Paul

[Merv and Sharon]

"Tim" Birkin one of the famous Bentley Boys of the 20s and 30s died from an infection from a side pipe burn.....

[Wazza]

On the long list of "Things I wanted on the new Cobra" has always been Live Side Pipes.

I have since driven a number of Cobras with live pipes, and spoken to a couple of the very best exhaust experts I could find.

I've now decided to go with an under car system.

I basically listed the pros and cons to make a decision.

Pros..

They are in keeping with the original design of a Cobra, so they should be on the new car.



Cons...

I'm not really making an exact copy of the "original" Cobra, so I shouldn't put live pipes on the car just to make it seem like an original Cobra...if you know what I mean

They burn you.

They burn other people.

The sound can be almost deafening when you're "Giving it a boot full"..which happens quite a bit!!
And I'll be driving 20,000 Plus kilometres a year in the car...i.e. a lot of time to not enjoy that buzz in my ears.

They're illegal in Queensland,
and I get enough attention from the boys in blue without asking for more....making it a real risk of spending a pile of cash , only to have the car sidelined until I spend another pile to make it legal

[U]According to the experts I've spoken to.[/u]......A good under car "X" pipe, or "crossover" system will produce "up to 40 hp more" than a set of Side pipes, on a fairly high h.p. engine.

Although I like the strong sound of a set of live side pipes, I like the sound of the under car balanced system more ...a good under car system sounds more like a V8 supercar ....to me anyway!!


Once I gave it all some thought....I realized which way I'd be going.


Suits me anyway...and I guess that's how we all should make our cars.... i.e. the way we like it, not the way everyone else thinks it should be.


Cheers

[Aussie Mike]

I've built a few sets of sidepipes now and they are difficult to get down to legal noise levels. I think the best I did was on Bernies Cobra and it was about 98dB or so and still ran OK.

The pipes I build are modular. You can pull them apart to repack them or change the baffle type for different aplications.



Here's a baffle in the making with a cat converter. The cats actually muffle a fair bit too.





I've just finished a new set for my own car and I've got a new flange design for the baffles which I reckon is easier to use. Boxhead has got a set on his Cobra with the new baffle design. I'll try to post some decent pics up shortly.

With the swapable baffles I can have a set of civilized baffles for the street with cats and more muffling. Whilst not truly noise legal they will be emission legal and quiet enough that you won't go deaf. With about 30 minutes work I can swap them to a 3" straight through baffle for the track. The baffle design also lets me adjust the collector length to suit my motor whilst maintaining a nice outside apearance.



Cheers

[Rebel1]

Wazza, I agree with everything you said, except I'll expand on one of your comments, ie. "They burn other people"

I fear that one day, some young child will stand on some hot pipes to look into the car. The end result will be a severely hurt child, a court case with no defense or insurance company involvement, and a $hit load of legal fees and compensation.

[spookypt]

So Wazza you still going to run "fake" side pipes???

It's guess it's like stuffing a set of socks down ya pants.... If ya dont have the bulge you "Fake" it!!!

In saying that though...... a smart move IMO. I have pondered selling my car because I can't enjoy it due to the LOUD live pipes!...... It's great to enjoy but drawers way too much attention.

I have an under car exhaust that I could retrofit..... but someone has been borrowing it for over 18mths. Perhaps its time to borrow it back!

One way or another I'm hoping to remedy the noise in the near future!

[Wazza]

So Wazza you still going to run "fake" side pipes???

It's guess it's like stuffing a set of socks down ya pants.... If ya dont have the bulge you "Fake" it!!!

Yeah....still love the look of the pipes, and there's the bling factor they give as well.

Anyway...I'll have a 7 litre bulge up front....not too worried about whether or not my exhaust system looks fake....... can't do much about it anyway.

Wazza, I agree with everything you said, except I'll expand on one of your comments, ie. "They burn other people"

I fear that one day, some young child will stand on some hot pipes to look into the car. The end result will be a severely hurt child, a court case with no defense or insurance company involvement, and a $hit load of legal fees and compensation.

That's what I was thinking.

Dropped a bike on a girl friend's leg at my 18th. birthday party...many ....MANY years ago, and she had skin grafts for months to get it fixed.

Had motor bikes for 10 years, and was always worried about kids touching the "pretty pipes".

I've had some little darlings standing on my fake side pipes at Q.R. at the triple 8 day, and the parents holding them so they wouldn't fall off while they were getting a closer look at the bumblebee...I think I wished they were hot enough to get them off that day !!

[boxhead]

Hogster, next time your in Alice and you want to see a set of the Aussie Mike pipes and hear them for your self, give me a bell and you can come around for a beer and a chin wag.

I have added a heat shielding material courtesy of another Member, I added it to try and lower the heat generated on the pipe (which it has done quiet well) but it has also made it alot quieter.

[Aussie Mike]

As far as the heat goes... With the pipes ceramic coated the surface temp is a lot cooler plus they cool down a lot faster. The danger window from turning the car off to the pipes being cool enough they won't burn isn't too long.

As Dave says, the type of material used for packing the baffles will also have a direct impact on the surface temp of the pipe. Gav has found some great fiberglass matting used for lagging pipes that works a treat.

Stainless or chrome plated pipes are another story. Stainless steel as a material inherently retains heat. That's one of the reasons it's popular for cookware. You also notice this when welding it as it takes a lot less current to weld as the heat stays around the weld area rather than being conducted away. It must be something to do with the chromium content in the metal.

It would be interesting to do a side by side comparison between a set of stainless side pipes and a set of ceramic coated steel pipes. Bring bith engines up to temp and let them run for 20 minutes or so then shut them off. Measure the surface temps of both types of pipe and graph them over time.

Cheers

[*Cobber*]

I have made stainless re packable side pipes for my car and although they get hot they also cool fairly quick too. I would doubt there is any noticeable difference in heat transfer or retention at exhaust temps between steel and S steel. When driving these cars it's pretty normal to linger around for a couple of minutes when you get out anyway so people can be warned of the hot pipes.

I agree a well designed under body system will yield better performance but in reality driven on the street these cars are not driven to ten tenths or anywhere near close.

Each to their own but to me the side pipes are a big part of a 427 replica, and if they are live all the better.

[Tatsushige]

When I built my cobra in perth in the early 1990's we were not allowed to have side pipes. So most of the guys has fake ones. I do not know the laws now but they may have changed!