Square port exhaust manifold on round exhaust port head (1 Viewer)

[donnerpassing]

Hey all,

small crack in my 1hdt exhaust manifold and thought I'd take advantage of it to replace it with a single cast manifold like the eclipse split pulse exhaust manifold. The description for it states its design is to fit HD-FT and HD-FTE with square ports, but bolts on and works well with HZ and HDT as well. Im looking at an exhaust gasket that I have, and I don't know how well it would really flow/how a square port manifold will mate well to a round port head. Just thought I'd ask the brains trust and appreciate the input as always

 

[PIP]

Cummins switched from square to round ports when they went 4V/cylinder. I've run square on round and round with the corners machined out on square and it works OK, but I don't think it's quite as good as ports that match.

 

[Dougal]

A step outwards going into the manifold won't be a big deal. A step inwards is a very bad thing.

All depends on how well it fits and what port shaping can help you with.

 

[MonsterCruiser]

I believe @ZCissner is running an Eclipse manifold on a 1HDT. Maybe he can chime in on the fitment of the Eclipse square port manifold to round head ports on the 1HDT. Which manifold gasket was used? Square or round?

I'm interested as well since I have an Eclipse manifold sitting here waiting to go on my 1HDT

 

[ZCissner]

I believe @ZCissner is running an Eclipse manifold on a 1HDT. Maybe he can chime in on the fitment of the Eclipse square port manifold to round head ports on the 1HDT. Which manifold gasket was used? Square or round?

I'm interested as well since I have an Eclipse manifold sitting here waiting to go on my 1HDT

Correct, I'm still running it, I used the standard OEM gaskets, no issues.