How much can damping be improved via balancer swap?

[89vette]

I'd disconnect the pipe mounts, and remove the cones if they are positioned to snub the vertical pipe motions, rev the engine up and down a bit, and" see" how it all feels.

Oh yeah!...

One thing I tried was installing flexible bellows in the belly -- before the exhaust pipe connects to the side pipes. My problem was worse. Though the bellows are designed for variable stretching with transverse engines, I thought they would help isolate that torque/yaw from the frame-connected piping. Seems like there should have been some isolation with the ability for the bellows to move laterally -- but maybe they aren't designed that way?

I tried this last spring.

Maybe I should consider addtional bushings (or replacements) where the pipes attach to the frame? But, if more movement (with the bellows) increased the problem, I'd have to guess more movement in the side-pipe-frame mounts might do the same.


Here's a link to a for sale thread in case you're interested in how the C4 system connects and is configured....
http://forums.corvetteforum.com/c4-part ... 986-a.html

[Kevin Johnson]

Did you try the stainless steel "flexible mesh fabric" (don't know the official term for it) type joint?

[89vette]

Yup. I'm that's what we used. It looked like criss-cross woven steel mesh.

At that time, I had a Y-pipe going into a center converter. I used two 2.5" mesh couplers going into the converter. The output of the converter included a flange that connected directly to the side pipe kit (as shown in the link above). I also included a support hanger from the manual transmission. It didn't help (or hurt).

That ceramic converter burned out in 2 months. I replaced it with straight pipe but I'm still running metallic spun bullet cats. They've lasted for 3.5 years. (Magnaflow peed over themselves trying to explain why the ceramic model burned out so fast.) The overall sound w/o the center converter is better though. Because the side pipes have built-in glass packs, the combo of spun-cats (with them) is mellow enough for neighborhood driving. Nice bark when revved!

FWIW: I had a SpinTech muffler before the Magnaflow center converter. Both the converter and muffler caused drone. The straight pipe config is actually better. I guess a lot of those cannister bodies create an "echo chamber".

I'm toying with the idea of wrapping the collectors with heat wrap and "cinching" the headers together for dampening. I would assume headers aren't as stable/solid as cast iron manifolds (or whatever they make those factory "shorties" out of.) Between much larger exhaust ports, headers, and the 4-2-1 manifold config, I surmise that more vibration is created...and travels down the exhaust than the prior 350 setup. Tieing the headers together (or adding mass) to dampen vibration is another option I haven't tried.