convert to undercar exhaust?

[txgoat]

Okay, I know I'm going to catch a lot of hell for this idea so let me have it right out front. That being said, my traveling companion(wife)is very concerned about the noise level on these side exhaust Cobras that I'm shopping to buy(Backdraft/351W). If it should come to be a problem, can one convert a side exhaust to a roadster undercar tailpipe system? Do you need new headers that dump towards the back? Of course, I understand that I would have an outlet hole in my lower panel. And I could always return the car to "stock" side exhaust when she finally loses her hearing or I sell the car. I'm thinking of something still kind of raunchy in a muffler with 3" pipes. Anybody ever do this or am I nuts to consider running a Cobra without the flash?

[aldersonjames20]

I always wondered about this myself. I also wondered if you could leave the side exhaust as is and get some custom tubing run at the connection point to redirect the exhaust under the car, but still maintain the look of the side exhaust. I don't worry so much about the noise (in fact I love it), but my travelling companion has already been bit by the snake... now if she loses interest, there goes my funding for the real fun, the mods etc.

James

[JBCOBRA]

Maybe just buy a car with rear exhaust to begin with?
Rear exhaust is great on long trips. A couple weeks ago my wife and I drove frome Valley Forge Pa. To Watkins Glen Ny. Cruised all around, did a rally with a bunch of Cobras (Jim Kellogg Erol Walsh Ken Arters) and lot of really cool other cars etc... and drove home. Over a 3 day period (close to a 1000 miles)
We had a blast. Hung out with great people. Met some folks from CC.
And I can still HEAR and my wife didn't burn her leg! LOL
JB

[Cobrabill]

Have her fitted for custom ear plugs.They're about 40 bucks.Problem solved.

[Dennis Kelley]

Find a new driving partner. Really

[bnewell]

I love the look of a Street Version car.......the lines are sooooo smooth and classic!!!!

Go with it!!!!

[WarrenG]

The rear exhaust was available for the original 427's so it's not like it wouldn't be a complete breach of originality. ERA offers that option for their 427, there's gotta be a way to do it in a Backdraft. With ERA's option the only issue is getting it past the brakes. I don't believe that their's works with outboard brakes, only the inboard brakes. If you can route the pipe around the rear axle and past the brakes, it'll work on yours.

[mickmate]

That's what I'm building so I'm biased(Check my avatar). I have a few pics of the undercar set ups on some Cobras if you need ideas. The sidepipes exit by your ears and the noise is an issue for many. Especially on longer rides. I don't believe you will have room to fit a 3" exhaust anywhere under a Cobra. Toughest part is already mentioned wiggling it round the rear end, check the ERA site they have a few pics also showing a street car with side exits in front of the rear wheel. I vote yeah obviously!

[NKOTB]

Go for the undercar exhaust. I pick mine up Thursday from Cobra Restorers. Mine is a street style though. When my car was originally built, the exhaust ran all the way out to the back. Then one of the previous owners had it terminated & kicked it out just in front of the rear tires (see my gallery). It used fairly flat oval mufflers tucked up between the inner & outer frame rails. Unfortunately the mufflers were pretty restrictive and reduced the pipe diameter down to 1 1/4' in and out of the muffler. The larger chrome tips you see in my pics were just for show. I do believe you'll need different angled headers & it may reduce your flow if you end up having to reduce the system's ID from what you have today. I guess you have to ask what flow capacity do you really need to have? The upside is that you will get the noise out the back & since you'll be passing most folks they'll still get the full effect as you go by. With this update, I was able to run 2" ID smitty's (pertronix) mufflers , so I basically have open dual 2" ID glass packs all the way back... According to Jimmy & Chuck that's what the original street's came with, so the sound should be more correct, and since my motor's not a screamer, it should be better than before, and still not restrictive enough to make a noticable difference in power output. Getting past the rear axle is the real challenge. I've seen folks run them down the sides, tucked up & over the axles when the car had inboard brakes, and with outboards, as mentioned above, & I've seen them run down the center of the frame L & R of the driveline and then around the pumpkin. I'll post some pics later this week if that'll help. Side pipes are nice, but with your junk tucked under, the lines of the car are more contiguous. Besides, your's and your wife's ears and ankles will thank you. Go for it.

PS: if your car's got stripes, go ahead and get rid of those too. IMHO, undercar exhaust only looks good on solid color cars... I don't think you find one instance of a striped car with undercar exhaust, even with all the permutations on this site.

DD

[Yetiman]

I prefer my undercar exhaust, but I am a big fan of the street car setup. My car originally had sidepipes, and was switched over to under car exhaust using a pair of Flowmaster mufflers.

The layout is very straight foreward, with short downward facing block hugger headers which have a bend back and two pipes going back to a crossover pipe behind the transmission, then out to the mufflers.

It's not perfect, but was easy to fabricate and works pretty well.
It DOES affect ground clearance some, as the front edge of the mufflers are the lowest point on the car, but it's quite livable.

The original Cobra under car exhaust (which the vast majority of cars left the factory with) was a pretty complicated series of pipes going over the rear axles etc.

I also have very short legs, and the sidepipes just wouldn't do it for me.

[Dwight]

If you like the looks of the side pipes, leave them but build a under the car exhaust system. Should not be that hard. Or buy a set of acoustic noise cancelling headphones and a portable CD player. I bought a set for $350 from Bose. Nice, Very Nice. I can still hear truck and car when they are behind me in that blind spot. Dwight

[Dinobyte]

What about this? Vintage Motrosports did it.

[fastraxsg]

Some how that billet looking outlet just doesn't cut it, a plain old slash cut would look better, there are a couple of cars on the site that have pipes that run along the bottom sill of the car and exit just before the rear wheel similar to the blue Unique in the tire ads. Saves the ears and still has that nasty competitiion look, try searching for these photos in the gallery.
13side.jpg or member name *13*

[jarendall]

why not put mufflers in your side pipes, have them cut and put in mufflers and then rewelded, if you have stright side pipes (without the glass packs) then you can have header collector mufflers put in, unless you cover the exit hole on the side of the car, it just won't look good, the slab side cars look good without side pipes, check them out before you buy

[Ant]

Having owned two Cobras, one I built with FE 390, and side pipes, it didnt really cause any problems on trip as the wind etc seem to overshadow the noise, unless you opened up the secondaries!

I am having built on this very race orientated Cobra and undercar exhaust as I cant stand sidepipes, I reckon they look like a hotrod, plus to get any reasonable muffles they need to be getting on to 5" diameter side pipes. Apparently the trick nowadays is with undercar exhausts, they dont use oval pipes, but a cones etc I guess speeding up and slowing down the air flow, I have a guy who builds exhausts for the Aussie Supercars, and its no problem to for him to build the headers and have two systems one for road and ...track!
He built a set for a friend who has a GT40, the mufflers are only as long as the transmission, and it is too quiet, and still goes like stink. I am not to sure how many pipes are going under the car, and I reckon he might start scratching his head when he finds how little ground clearance these cars have.

Go for the undercar exhaust, but try and avoid using a small diameter pipe over the rear axle, there must be better options than that, plus as mentioned maybe use two smaller diameter pipes under car, and locate muffler more to rear of car where there is more ground clearance!

[fastraxsg]

Some real nice shots of a very neat set up for undercar exhaust can be found by checking out one of the member's gallery. Do a search Gallery for user name leeroy. He has a really well done under car system.

[Tom Wells]

Here's my 3" undercar exhaust:



and here's the car:



It isn't quiet, but it never snake-bites

[aldersonjames20]

Originally Posted by Tom Wells

It isn't quiet, but it never snake-bites

How hot does the floor get under your seat where the box is? Did you cover it with some sort of heat guard?

Did you do the cutting through the frame components to get it through?

James

[sfeakes]

As someone already said, Vintage did it, and it was to a Backdraft.
http://www.vintage-motorsports.com/g.../BDR193?page=1
There used to be a complete picture set on their site that showed you everything you needed to do to make this work on a Backdraft, but I can't find it now.
Since Vintage is a Backdraft dealer, and have already done this, you may as well give them a call.
You can search this site and find an amazing set of referances for them.

[SP01715]

Here is a pic of the exhaust on my car. It has Magnaflow mufflers and heat sheilds above them. I think the exhaust with the mufflers sounds better IMO than the side pipe cars I have driven. It is still pretty loud though.