indmar exhaust question...

[396_WAYS_TO_SPIT]

How restrictive are indmar exhaust manifolds??? My friend has them on his 502 and was curious. Are these good manifolds??

[Riverjet502]

I think they are a tad better then logs. Not quite as restrictive. I had a pair on a stock 350 in the past. The manifolds are open in the inside. What I am trying to say is that the engine’s exhaust dumps into the manifold and shares exhaust with the rest of the exhaust on that side of the engine trying to exit the engine. Not the best for scavenging exhaust from individual exhaust ports. This is why your better center rise manifolds have individual runners for each exhaust port cast into the manifold to eliminate the reversion of exhaust bouncing off one another inside the manifold on its way out.