Exhaust for 4106

[eddieboy]

Thanks for all the pics.  I was out welding 2 elbows together tonight.  I will get some pics online once I get her finished. I am planning on taking it out through the roof.

[RJ]

I am planning on taking it out through the roof.

Eddie -

Does your coach still have the rear window in place?  If so, you can do what GM did on their transits, and bring it out thru the LH small glass area, curving the tailpipe to match the curve of the roof.

But be careful - you will have to run the pipe thru the passenger compartment, and this increases the risk tremendously for carbon monoxide infiltration into the cabin - not a good thing!

I looked into doing the roof exhaust thing also, but decided I didn't want to run the risk of CO in the cabin.

In addition, having the exhaust exit thru the roof takes away one of a driver's tools to determine if you're lugging the engine, especially when climbing RockyTop.

With an exhaust similar to stock, you can see when the engine's starting to blow black smoke when grade climbing, indicating it's getting time to downshift.  Roof exhausts are almost impossible to see in the exterior mirrors when they're properly set for monitoring traffic, especially on the shorter 35-foot coaches.  Since you can't see the exhaust easily, there's a greater tendency to overheat the engine, which can get expensive really quick.

You might want to consider what GM4106 has done, using that Donaldson muffler.

FWIW & HTH. . .

[CraigC]

I have a friend who took a new 4106 muffler he cut it in half. I mean 1/2 it's original height and removed the baffle. He added a second 3" outlet because he also felt the engine was to restricted. He ran one to the LH rear corner and used mainly flex pipe to run the second pipe the the RH corner. The sound is very reasonable up close. I believe it is because the noise is pointed in two directions. He also wanted a little more access room that was another reason for cutting down the muffler.
He also fabricated the rest of his exhaust system from parts available at the local truck parts house. It is very similiar to the stock configuration for the exhaust system.