Exh. Port & Cast Iron Turbo Manifold Matching?

A

Anonymous

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On naturally-aspirated engines, the exhaust port at the head/factory manifold or head/header joint is somewhat smaller that the manifold branch or the primary tube into which it dumps; the reason given is sonic reversionary wave damping.

Hooo-kay....

"Gasket-matching" is also a normal porting activity, and the assumption is that the head's exhaust ports now match the gasket, and on a round-tube header there is a good likelihood that match won't be perfect, and some semblance of reversion wave damping will be maintained.

How about porting factory cast iron exhaust manifolds, particularly an I-6 cast-iron turbo manifold? Will this dampening "ledge" need to be maintained? If so, is there a formula for computing the anti-reversion area needed?

Or can both head and manifold be perfectly matched to the gasket for a "seamless" transition?

Eddie
 
WELCOME BACK!
We've been wondering where you got off to.
Anyway, if you thing about what's going on in a turbo, every single blade is going to set up a reversion wave, that's a whole lot of Hz. Whatever you're worrying about in the exhaust pulses dims by comparison. I suspect you've never seen a technical treatment of the subject because the late Prof. Smith never had access to a Cray.
 
...The view from Out There is Far Out, and "They" were far too busy trying to catch me for alien experiments (commonly known as "divorce proceedings" :eek: ) to bother bringing my Favorite Sleep Aid (A/K/A "Ol' Doc Smith").


The Ricediesel project is back on track, and that '87 4.9L head I bought off Ted is at the machine shop presently for valve seat work (inserts, O/S naturally :LOL: ); next step, port work, then cryo, then heat-barrier coat once I decide if the 4.9L is going to be a blower motor or stay N/A, i.e., high or low CR.

It turns out we have a couple of world-class cryo and coating shops right here in Houston, and I really believe both of those processes will lend a high degree of durability to some highly stressed pieces; pistons, for example.

Eddie



 
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