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-   -   Undercar exhaust exiting ahead of rear wheel (http://www.clubcobra.com/forums/all-cobra-talk/116938-undercar-exhaust-exiting-ahead-rear-wheel.html)

lippy 08-24-2012 05:29 PM

Undercar exhaust exiting ahead of rear wheel
 
This is an option I've begun to consider on my build because: (1) I sort of like the look, (2) no burns, and (3) I understand there is more flexibility for mufflers/sound/restriction.

Does anyone have experience with this, the pros/cons, and if they would do it again? Any other opinions appreciated as well. Thanks!

blykins 08-24-2012 06:09 PM

Didn't do it on mine, but I much prefer the sound of undercar exhaust over sidepipes...

Jaydee 08-24-2012 06:48 PM

Sound like a good idea. Have you got pics yet?
Is there room to put mufflers under the chassis? Where are most located?
JD

Tom Wells 08-24-2012 06:57 PM

Lippy,

I have'em and I love'em. The only snakebite I ever got was while working on another Cobra guy's car...

Here's a shot of the passenger side with the body off:
http://www.clubcobra.com/photopost/d...hassisLeft.jpg

You can see the notch in the front outrigger support that E-M put there to allow some ground clearance.

And here's the finished product:
http://www.clubcobra.com/photopost/d...on-grass6a.JPG

Spintech made the mufflers for me. Their stock ones proved a little too wide and made one of the world's loudest rattles. After they made some for me about 3/4" narrower, they've been on there ever since. They are not SS so they are coated.

I have SS headers and pipes. This was another series of learning experiences, as the routing and fit of the pipes needs to be done correctly. If they're hanging down a bit too low, well, let's just say it makes a noise that's a lot louder than a rattle!

The pipes are 3" all the way. If you have a smaller engine (mine's a 521) you could likely use 2-1/2" and not eat too much hp.

There's a standard rubber hanger (sort of elongated O-shaped) just before the exit bend, holding onto the the pipe using a piece of 3/8" rod welded onto the pipe, and a similar hanger under the frame.

I would have taken them out to the back bumper to make it quieter on 400-500 mile days, but there wasn't any space for the tailpipes.

Enjoy,

Tom

mickmate 08-24-2012 09:39 PM

What kind of car/chassis are you considering it on? I think it's kind of neat FIA looking.

tkb289 08-24-2012 10:29 PM

Lippy,

If I reall correctly, you are building a 427 ERA.

I put an under car exhaust, exiting before the rear wheel on my ERA FIA and really like the look, sound and no snake bites! I would do it again.

The muffler that fits & ERA recommended is the Dynomax #17762. It just fits between the frame outriggers, and the main frame rail & bodywork. Not sure if the frame setup is the same on the 427 ERA car. Best to check with Bob to see how much room there is. Also, if you are considering this option, be sure to let Peter know before they cut holes in the fenders for side pipes.

You will lose some horsepower compared to traditional 427 side pipes, which may or may not be a big deal for you. Also, if you go with the Jag rear suspension from ERA, you have the option of exhaust to the bumper should you want to try that.

Start with the under car setup, if you find you don't like it, you can always cut the fenders and go with side pipes.

Thor maine 08-24-2012 10:32 PM

I like that system. But there has to be some way to have the under car system with some kind of cutout go to the sidepipes for the rock n roll sound. I love the sound of the sidepipes but most of the time I would like it not so loud it sets of bank alarms.

blykins 08-25-2012 06:41 AM

I don't think I agree with an undercar exhaust making less horsepower. It just depends on what size mufflers you go with.

However, most sidepipes are extremely restrictive and the collectors on sidepipe headers are sometimes at extreme 90° angles. There have been members here that dyno'd with and without sidepipes and there has been 100hp difference.

The horsepower difference is one of the reasons why I would go with undercar exhaust...

Young1 08-25-2012 07:06 AM

Just be sure to get your seat mounts and belt mounts where you want them. The nuts will be above the muffler. Put some radiant heat barrier on the underside of the body too. Keep the legs and butt cool.

wolf k 08-25-2012 09:51 AM

Lippy, I went with under car exhaust for all the reasons you mentioned and would do it again on my next one. ERA cars do not have nearly as much room for mufflers as the EM car pictured. Therefore, your muffler choices are limited.

http://i298.photobucket.com/albums/m...n/DSC00506.jpg

ERA Chas 08-25-2012 10:15 AM

Wolf-unless you have already, consider insulating the brake box against pipe heat.
Jus sayin'...

lippy 08-25-2012 01:30 PM

Quote:

Originally Posted by mickmate (Post 1206876)
what kind of car/chassis are you considering it on? I think it's kind of neat fia looking.

era 427

How does the undercar exhaust compare in price to the sidepipes?

LMH 08-25-2012 04:03 PM

I've seen a couple original 427's that have the exhaust exit in front of the rear tire. I like the look.
Larry

Bruce M 08-25-2012 05:09 PM

My Contemporary has. 502 Chev w/ 3" collectors into 3" Flowmasters up and over w/ 3" SS tips out the rear. Looks great, sounds great and no burns!! Had to install heat shields and lined cockpit w/ asbestos aluminum foil fabric before interior was installed.

HealeyRick 08-25-2012 06:13 PM

Quote:

Originally Posted by Tom Wells (Post 1206844)
Lippy,



Spintech made the mufflers for me. Their stock ones proved a little too wide and made one of the world's loudest rattles. After they made some for me about 3/4" narrower, they've been on there ever since. They are not SS so they are coated.

I have SS headers and pipes. This was another series of learning experiences, as the routing and fit of the pipes needs to be done correctly. If they're hanging down a bit too low, well, let's just say it makes a noise that's a lot louder than a rattle!

The pipes are 3" all the way. If you have a smaller engine (mine's a 521) you could likely use 2-1/2" and not eat too much hp.

There's a standard rubber hanger (sort of elongated O-shaped) just before the exit bend, holding onto the the pipe using a piece of 3/8" rod welded onto the pipe, and a similar hanger under the frame.

I would have taken them out to the back bumper to make it quieter on 400-500 mile days, but there wasn't any space for the tailpipes.

Enjoy,

Tom

My Austin-Healey probably has one of the least amounts of ground clearance on a production car. When I did the small block Ford conversion, I really had to search for a suitable muffler that would save me from tearing out the exhaust system on any kind of bump. I went with the Spintech Cruiser series, which looks a lot thinner than the model you have. They measure 2 1/4" thick and come with oval inlets up to 3" Here's the link: SpinTech Cruiser Series - Mufflers - Street Mufflers - LOW PROFILE STREET MUFFLERS - 7000 CRUISER SERIES OVAL OR ROUND COLLARS - SpinTech Performance Mufflers

Here's what they look like on the Healey:

http://i81.photobucket.com/albums/j2...k/IMG_0209.jpg

I have 2 1/4" pipes on a 345 crank horsepower motor. You can also see the self adhesive DEI Reflect A Kool aluminum covered insulation that I installed above the mufflers: Reflect-A-Cool 010460 | Purchase DEI, CryO2, Ny-Trex, Boom Mat & SPA Turbo Products | Design Engineering, Inc. - Thermal Performance Products

And this is what the mufflers sound like:



(The system is a dual system with the right side pipe crossed over behind the axle to give the look of the stock twin pipes)

DanEC 08-25-2012 07:09 PM

Quote:

Originally Posted by Tom Wells (Post 1206844)
Lippy,

I have'em and I love'em. The only snakebite I ever got was while working on another Cobra guy's car...

Here's a shot of the passenger side with the body off:
http://www.clubcobra.com/photopost/d...hassisLeft.jpg

You can see the notch in the front outrigger support that E-M put there to allow some ground clearance.

And here's the finished product:
http://www.clubcobra.com/photopost/d...on-grass6a.JPG

Spintech made the mufflers for me. Their stock ones proved a little too wide and made one of the world's loudest rattles. After they made some for me about 3/4" narrower, they've been on there ever since. They are not SS so they are coated.

I have SS headers and pipes. This was another series of learning experiences, as the routing and fit of the pipes needs to be done correctly. If they're hanging down a bit too low, well, let's just say it makes a noise that's a lot louder than a rattle!

The pipes are 3" all the way. If you have a smaller engine (mine's a 521) you could likely use 2-1/2" and not eat too much hp.

There's a standard rubber hanger (sort of elongated O-shaped) just before the exit bend, holding onto the the pipe using a piece of 3/8" rod welded onto the pipe, and a similar hanger under the frame.

I would have taken them out to the back bumper to make it quieter on 400-500 mile days, but there wasn't any space for the tailpipes.

Enjoy,

Tom

How do the spintek mufflers sound on your car? I've heard they are pretty loud. I have 2-1/2 inch ones mounted on my ERA with 2-1/2 inch pipes all the way out the back end, but I'm some ways off in my build from being ready to fire up the motor.

Thor maine 08-25-2012 09:47 PM

has anyone done a dual system???? I remember something about Storming Normin at the Run and gun with some kind of dual system. I can't be the only one who would like a quiet muscle car and the world beating punch you in the face pin you to the seat while you plug your ears kinda car???

tkb289 08-25-2012 10:50 PM

Quote:

Originally Posted by blykins (Post 1206911)
I don't think I agree with an undercar exhaust making less horsepower. It just depends on what size mufflers you go with.

However, most sidepipes are extremely restrictive and the collectors on sidepipe headers are sometimes at extreme 90° angles. There have been members here that dyno'd with and without sidepipes and there has been 100hp difference.

The horsepower difference is one of the reasons why I would go with undercar exhaust...


Brent,

I agree ... it does come down to what muffler one uses. In the case of 289 ERA, as Wolf mentions there is not a lot of room to tuck a muffler up underneath the car, at least on the FIA, can't speak to the 427 ERA.

The dynomax #17762 that fits is not that large ... 2" diameter pipe IN and OUT, but it flows pretty well and sounds great. I would think the true FIA side pipes would flow better, but without a side by side comparison hard to say for sure.

The custom SpinTech mufflers that HealeyRick is running look like they would fit under just about any car.

I like the looks of the under car setup and makes getting in and out that much easier.



http://i616.photobucket.com/albums/t...t/DSC_0069.jpg


http://i616.photobucket.com/albums/t...t/DSC_0077.jpg


http://i616.photobucket.com/albums/t...DSC_0910-1.jpg

Jaydee 08-26-2012 03:13 AM

How quiet is it with the dynomax muffler?
Also some v8's have a balance cross over pipe, is that necessary?
With the underbody pipe, I have seen a stainless steel side plate along the body, wich looks nice and stops stone chips on the rear guard.
JD

DanEC 08-26-2012 04:10 AM

Wolf K and TKB289
 
Did either of you have any problem with the passenger side ERA collector placing the muffler a little too far to the outside to where it interfered with the body rocker area? I had to take mine down to an exhaust shop and have a 2 degree bend put in it to center the muffler in the proper area for clearance. I hate having that slight kink in it but it will only be visible from underneath. It looked to me like the shop they have fabbing up the exhaust headers and collectors isn't allowing for the 1 inch offset of the motor to the passenger side. Or maybe it was something just unique to mine.


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