Exhaust manifolds: single vs two piece (1 Viewer)

[ATL Cruiser]

I was given an Eclipse single piece exhaust manifold. I'm debating installing it.

Besides losing the heat shield, I'm curious the downsides to this single piece manifold. I've heard that Toyota built the manifolds in two pieces to prevent cracking manifolds and/or pulling studs.

Any truth to this?

 

[Irish Reiver]

I'm no expert in this field but two issues jump to mind. First is that you will need to find a single pipe downpipe and second there must be a huge amount of flow restriction when you try an cram the output of 65 cylinders into one pipe versus 2 pipes on the OEM.

 

[Rusty Marlin]

Yes, the delta thermal coefficient of expansion between aluminum and iron is high enough that in long lengths it could defiantly shear or loosen studs depending on the true position tolerance at MMC of the hole to the stud.

Iron head to iron manifold is no problem, like the Ford I6 300.

 

[Rusty Marlin]

I was given an Eclipse single piece exhaust manifold. I'm debating installing it.

Besides losing the heat shield, I'm curious the downsides to this single piece manifold. I've heard that Toyota built the manifolds in two pieces to prevent cracking manifolds and/or pulling studs.

Any truth to this?



View attachment 3112255

My guess if for cast-ability and maintaining a reasonable flatness before machining the mounting face.

 

[AussieHJCruza]

I assume this is for a 1HD-# - iron head, so no expansion issues. Apparently they flow better than a stock manifold but I've never run side by side on the dyno to see if it makes any difference.

 

[ATL Cruiser]

I assume this is for a 1HD-# - iron head, so no expansion issues. Apparently they flow better than a stock manifold but I've never run side by side on the dyno to see if it makes any difference.

Yes, I probably should have clarified this, as the head material matters. Aluminum is going to expand vastly different than cast iron.

It's a 1HZ. So a cast iron head.