I know that the SSCA had an articles about this project in the SL6 News many years back.
There have been other pieces of info. about the "remaking" of the Hyper-Pak posted on the internet, here is some of that info:
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A lot of development work and time went into the casting equipment used to reproduce the Hyper-Pak intake.
If it were not for the help of ex-Chrysler engineers like Pete McNicholl and Tom Hoover, this project would have never gotten off the ground. (these guys still had all the specs, blueprints and dyno test data, plus they helped me "sort-out" the mixture distribution on the reproduced manifold)
The new casting patterns were built in 1993-94 with the first manifold produced in the late summer of 94. The casting equipment (patterns and core box) are made of wood, fiberglass and a low shrink plaster, this is considered low cost, short run tooling, good for an estimated 50-100 castings. http://www.dutra.org/pictures/engine/pa ... roject.jpg
A total of 41 castings were made with the "Dutra" name cast into them, the first 10 were big port (1.25 x 1.65) "Fat Pak" manifolds. The runners were downsized to 1.2 x 1.5 for the remaining 31 units made there after. Of these 31, 6 "specials" were made. 2 units had a divided plentum area, 2 were longer runner 2 bbl versions and 2 had a front-back mounted spreadbore carb. mounting pad. http://www.dutra.org/pictures/engine/pa ... ecials.jpg
The larger carb. mounting pad and NOS injector bosses at the end of each runner were added onto the last 21 Dutra Hyper-Pak castings.
The casting equipment built "changed hands" to Clifford in early 1998 for the simple fact that the local foundry Dutra used to cast the first 41 manifolds closed down. By this time the casting equipment was worn and needed to be "refreshed".
It took Clifford a little over a year to produce more Hyper-Pak manifolds with their name on it. The word is that they had to re-make the core box so the runner passageways would be closer to the stock 1.12 x 1.44 size. From the outside, the Clifford H-Pak manifold looks the same a Dutra unit, except for the name change, so I would guess that the same "temporary" wood and fiberglass external patterns are still in use. My guess is that Clifford has produced another 30 to 40 units off the revised Dutra casting equipment.
Hate to say that I no longer have many of the Dutra Hyper-Pak manifolds I made, I think I kept 3 of the specials.
If anyone really wants a Hyper-Pak manifold, I would say that now is the time to get one form Clifford or locate one out in the "used parts" marketplace.
Seems like Clifford just finished-up a fresh "lot"of castings and the $300 price they are offering is pretty good. (I was selling these for a bit over $400)
Two things will happen in the next year or so:
-Clifford will continue to get more and more difficult to deal with now that Jack Clifford has passed-on. (it's hard to say how they can get worse...) Some say that Clifford may "fold", the new management at Clifford says all is well.
-A new SL6 Hyper-Pak engine build-up article will come-out soon (Most likely in Mopar Muscle)and that could create some new demand for these manifolds. (it's a H-Pak Aluminum Block build-up and "road test")
I know from my own casting experience that committing to *another* run of any casting is always a big decision and "up-front" cost. Jack Clifford was the guy managing that part of their business so who knows who (or if)someone will pick-up that activity for Clifford, now that Jack is gone.
DD