Engine/Transmission (1994 - 1998) 3 piece manifold?

[velsberry]

I've noticed several sigs that contain "3 piece manifold" (I assume exhaust) and I would like to know what benefit it provides. I don't have polished or ported heads, or O-ringed head,etc. Thanks for any info.

 

[DHayden]

ATS and HTT sell 3 piece manifolds. The advantage is that they are able to expand and contract from the heat without cracking like the stock manifold does. They do flow better also, I just did a ATS intake and HTT exhaust manifold on my truck and the difference was suprising. Although the only reason I bought it was so it wouldnt crack.

 

[Woodenhead]

Not sure if it's an issue on the 24V motors but on mine the exhaust manifold shrunk to the point of bending the stud on #1 cyl. The gasket on #1 was stretched and trashed from the manifold expanding and contracting with heat and having a "ratcheting" effect pulling on the gasket. I've heard if it goes long enough it can shrink to the point where it breaks the piece off the head where the stud is threaded into. That's why I bought my ATS 3 piece.



Mike

 

[Bart]

Like Mr. Velsberry, I'd like to know about this. I have 160K on my 98 12V'r and don't "think" I have a problem with the exhaust manifold.

Dhayden, what to you mean by "difference was surprising"? In what ways. I'm looking for MPG I get an average of 16mpg driving my 3500 with a 11' cabover on long trips doing 1500 rpms (57mph).

 

[DHayden]

I was suprised because I wasnt expecting much difference in performance. I replaced my intake and exhaust manifold and dropped 10. 1 pounds of boost and egt dropped 50-60 degrees. You can read the exact numbers in this thread:



http://turbodieselregister.com/forums/showthread.php?t=141254