I'm sill looking for advice on the hyper pak. Where in the RPM range is it better than a standard design, and by how much? Is their a drawback to using one? I'm thinking MPI here, but would like to know effect on carburetor also. Any pratical experience out there? Any dyno numbers available?

According to my sources, the HP is good to around 5500 or so and makes really good torque down low. I just stumbled on to a Clifford HP. I'm gonna try it this summer if I can get it to clear my hood on the '66.

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Official Cookie and Mater Tormentor.

Does anbody know if there is a horse power gain anywhere? Does anybody out there have one of these in operation with experience as to the improvement? What is the theory behind the longer runners? Is it eveness, or velocity, or both?

I would like to more about the hyper-pack intake as well. What are the issues, or things to look out for when using one on a mostly stock street slant? I'm not really worried about the throttle linkage or kickdown linkage, but since the hyper-pack is much longer than a stock intake, would I need some extra support for it?

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"Ja, Ich fahre ein altes auto."
'78 Volare 225
'67 Charger 318

I am currently running a Hyper-Pak on my drag car.
The set-up runs mid 14s with basically a stock short block, performance cam and a trick head. This lines-up to the performance figures I saw from the days when the H-Pak kit was offered "off the shelf".

This is a ram tuned intake, the idea here is that the pulse waves (harmonic pressure waves) can be used to create positive pressure in the intake track. This happens in a narrow RPM range, my current set-up "tunes" at 4200-4600 RPM, my in car vacuum / boost gauge actually goes positive a couple of psi at that RPM, it is free supercharging. The down side is that this ram effect starts to work against you after 5500 RPM or so, the short runner manifolds really start to work well at the higher RPMs.

A Hyper-Pak is a proven factory designed system that works.
It is great as a street performance set-up as long as you can deal with the cold blooded manners of a non-heated intake manifold.
The factory "tuned" this manifold so a 170 cube road race Valiant could come off a corner strong in the 4000 to 5000 RPM range. Working with cam, carb size, gearing etc, Hyper-Pak combos can be "tuned" to work well anywhere between 2500 and 5500 with super strong
power focused in a 1500 RPM "power band".
DD

Dennis, I can't wait until the summer! Well, maybe I can. I still have to save up some cash.

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"Ja, Ich fahre ein altes auto."
'78 Volare 225
'67 Charger 318

Thanks Doc.
That was a very helpful answer. Now I have to ask, how does the hyper pack compare in all those repspects to the stock Clifford manifold. For an an engine living mostly below 4500, does the Clifford manifold share the qualities you listed for the Hyper pack, or is it superior in some ways? For instance,does it have broader power band, or about the same. Is power down low better? Does the Hper pak provide more equal flow from cylinder to cylinder. I am getting ready to buy one or the other of these, and need help chosing. Until recently the hyperpak was an exotic collectible. Now it's on the platter to be choosen from, just like that dessert tray they bring around after diner, tempting me to go for it.

If anyone is considering a HP manifold, don't wait too long. I ordered one this week after hearing there was 30 in stock and no more will be cast. While I was on the phone with Clifford, I asked about headers. I was told there was only one set for cars '60-'81 (55-0100) and one for trucks, all others were being dropped. The 4 barrel non-water heat manifold (45-4500) is discontinued, only the water heated (45-4500WH) is still stocked. The answer on the header puzzles me as their 2000 catalog shows header 55-0100 to fit '60-'66 and 55-0144 to fit '67-'81. He did say single outlet header 55-2600 (fits'60-'81) was no longer. Appears if they are going to carry any slant parts, it will only the higher volume sellers.

Cecil

Vader, keep in mind that the HP intakes do not have the 45 degree injector bosses that the standard Clifford intakes have. You would have to weld on injector bungs. My intuition is that the standard intakes would have a wider tuning peak (and higher) due to their wider range of runner lengths.

IMHO, those 55-0100 (street rod) headers are great street/strip units and fit well into early and late As. Too bad they are discoing the others though. That's really weird they would disco the standard 45-4500 intake as that is probably the most popular one!

That's a cool observation with the vac gauge, Doc. I gotta try that. I suppose on a standard manifold the tune is around 6000 so you'd really have to buzz it up there to see the peak.

Lou

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Home of Slant6-powered fun machines since 1988

What else is out there for intakes on the market?

I would say that the standard Clifford intake with the large angled bosses would be your best bet for a "quick and easy" EFI manifold.

As Lou stated, the shorter manifold will have a wider power range. (band)
Fuel distribution is not a factor with a "port injector" EFI system. These systems spray equal amounts of fuel into each runner so cylinder to cylinder "load" is spot-on even, that is the main advantage to "dry manifold" EFI.

Having even fuel distribution allows you to lean down the whole system and to get maximum timing advance into the engine without your lean cylinder(s) being the limiting factor. (there are no lean cylinders)

On an EFI engine, Head port flow and combustion chamber volumes (cc's) become the focus points. Get all the ports to flow the same amount of air, get all the combustion chambers the exact same size, (compression ratio)deliver the exact same amount of fuel load and timing to the charge and then, be able to adjust that "on the fly, 60 time per second with a computer, that's how the new cars get so much power and MPG out of those new engines.
It is not "rocket science", just a bunch measuring and fancy engine build-up prep work. (a quench type cylinder head would also help, that is our current "bleeding edge")
DD