Facts on aftermarket 3 piece exhaust manifolds.

[Pascalray]

Is there any definitive real world experience with these aftermarket exhaust manifolds actually producing more power and efficiency?

 

[HBarlow]

I don't think anyone sincerely claims performance improvements but the three piece exhaust manifold doesn't expand and crack or break the bolts like some of the oem's do.

 

[Joseph Donnelly]

you mean shrink lengthwise. For most of us, any performance enhancements would be minimal. It is a matter of preserving the engine from damage.

 

[EDankievitch]

That and they look really cool.

 

[HHhuntitall]

Originally, I bought one for my '97, as I suspected it was what cracked my cylinder head around #6 injector. New head, new exhaust manifold. I noticed a 3-5 psi gain on max boost, depending on temperature and air quality. Next, I bought one for my '96. It did the same thing, 3-5psi boost increase. EGTs on both went down @ 100-200 degrees. I was sold, and anything I pull a trailer with has one. On my '03, boost psi at cruise went down, overall boost didn't really change, but EGTs went down several hundred. Personally, I think Cummins should have done it from the start.

 

[Harlacher]

There have been test done to prove under certain conditions the upgraded manifolds will increase your horsepower. There is a thread on the TDR that explains how they can increase it if the situation is right. If I remember right in some cases up to 15 HP gains were seen. Do a search and I am sure you will find it.