HP repop manifolds

Maybe this should go in Q&A...
But since it's a Restoration item, and most of the resellers lurk here... I'll start here.


My question is this... (based on what FAST guys are doing with them)

Are all of the current Repo HP Manifolds "Exact" reproductions internally?

Here is why I ask...
I have spent years in the boating world, where cast iron exhaust manifolds are the norm.
However over the years several aftermarket companies, like GLM, began to manufacture improved replacements
These replacements incorporated internal casting changes that were far superior to the original designs, yet looked exactly the same externally. (Some even cast them in Aluminum) Eventually the original manufacturers also implemented the same internal changes allowing for improved exhaust flow across the board.

From what I've read, the FAST guys have figured out how to make the stock exhaust "Flow Better".

So, my question is...
Has anyone incorporated any of those "changes" into the internal casting of the new Repo HP Manifolds?
If not, why not?
I would think there would be a strong market for anything with improved flow, just like the marine counterparts.

Just wondering.
thx

Just a guess, but I would think the f.A.S.T. guys are using the Extrude hone process of liquid media being run thru the ports/passades until they are smooth and hogged out as desired

Yup - They use Extrude-Hone. I am sure the makers of the manifolds wont pay up for precision castings because of the volume as compared to the Chevy stuff.

Im buildin a FAST car now and bought a set of the repop manifolds which are n the process of getting extrude honed out.going to hog the hell out of them as well as a intake manifold. i didnt want to ruin a good set of original manifolds.

Quote:

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Im buildin a FAST car now and bought a set of the repop manifolds which are n the process of getting extrude honed out.going to hog the hell out of them as well as a intake manifold.

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Which was kind of my point...
You would think someone would have made a set that was already bigger & smoother inside.
If your going to to go to the trouble of casting them, I would think it would have taken very little "extra effort" if done up front.
The guy with the ability to advertise "Flows Better than Stock" would have an an advantage over dead stock repops.

At least I think he would.

But it appears that is necessary to buy them and then "Fix" them after the fact.
Which answers the question "If they do it?"