High rise manifolds

[Kodiak Island Modeler]

I always thought that high rise manifolds looked cool, and used with dual quads, they were quite an impressive sight. I know that they were used a lot during the seventies, but what years were they popular? Why aren't they used much now?

[roadhawg]

2 things......first, fuel injection is the standard now, and second, emissions. They were cool though.

[roadhawg]

As far as years, if you mean from the factory, mid 60s was the last multiple carbs, and 72-73 were the last high rise intakes. As always, I might be wrong.

[ChrisPflug]

I took the original post to refer more to tunnel rams on street machines rather than factory setups

In the past this was the popular "all-out" performance setup- since the late 80s or so other "higher tech" options offering better streetability including upgraded fuel injection and wider use of bolt on centrifugal superchargers make good power more efficiently. In the 70s there was very little "new" performance technology as far as the basic engine parts like cylinder heads and camshafts- hot rodding was still "stuck" in the late 60s- development was more expensive and more limited to the OE manufacturers who had the resources but were using them to reduce emissions and meet regulations rather than spending a lot of time developing performance parts

[moparmagiclives]

The long runners of the tunnel were used with the camshaft to tune the power and at a higher rpm, an ECM and injectors can that now. But even as far as carbs go, they didn't make that big of a difference over one and a good single plane after a wile.

[Dr. Cranky]

Actually, it would be very cool to get some pictures of them up. Just to see a variety of possibilities. I know the 66 Nova comes with one.

[Greg Myers]

Several things come to mind here. First the term " High Rise Manifolds" I can think of three different styles that would fit this description. First would be the Ford 427 High Riser used in all kinds of Ford products from the '60's i.e. the big block Galaxies,427 cobras and the Thunderbolt Fairlanes, with the term "high rise referring ti the gradual increase in height of their manifolds,again i.e. stock, medium riser and high riser.

The second high riser that came to mind was indeed the tunnel rams of the '70's.

Lastly, anything high enough to stick out of the hood.

Edited February 28, 2012 by Greg Myers

[whale392]

Shane, it is the other way around. Long runners provide much needed low-end torque production, short runners are used for high-rpm HP. Cams can be cut and dialed in to take advantage of both the intake and exhaust pulses, and to 'tune' the helmholtz resonance (otherwise known as reversion) to get an engine to respond in a certain rpm range.

As to the tunnel-rams.........we had one on the dragster in the middle to late 70s to try and give it some low-end grunt. The Hemi suffers from no low-rpm flow, and both torque and horsepower are down in the low rpms. The tunnel ram helped slightly, but was not worth the effort and extra weight it added. Better carb tuning and a cam cut for the intake/exhaust really woke the car up. They are cool to look at, but really out of place in the modern EFI world.

[Greg Myers]

Now if you smoosh em down you get "cross ram" :

and again several choices:

and heights :

[whale392]

Interesting thought, Dave, as the 'Ram we had on the rail actually worked better down lower. As a product of runner length and its' effects on torque/horsepower, the short-runners function far better at mid-high rpm. That is why a single-plane works better at the track than a dual-plane intake. The dual-plane has torque down low, but the long runners inhibit high-rpm flow. The single plane has a plenum effect at low-rpm, but helps velocity at high-rpm.

Now, with the Maxi-Hemi (race Hemi) and the 426 Max Wedge Short-Ram intakes, they have huge plenums followed by fairly short runners, good for the rpms these engines were designed to run at. Same with the NASCAR single-4 plenum intake. Worked great at 6,000rpm all day long.

Edited February 28, 2012 by whale392

[whale392]

What you discovered about the 2-4 low-rise was the wonders of too much carburation. Had a 361 with the 383 2-4 intake. Took it off and ran a single 4. It gained almost a half-second at the track. Just for a 'what if', we took a 2bbl intake and dropped it on (the 361 used was a 4bbl car originally) along with a larger 2-barrel carb. It gained .2 second over even the 4bbl intake. Later, the engine was built and cammed, and the same 3 intakes were tried again. This time, the single-4 dual-plane (with the split milled/notched) performed the best.

I will agree that a Tunnel Ram is cool looking for a vintage era build and for the street rod crowd. Me, I like sneaky and subdued. I'll hide my blower and EFI under my hood, thanks. No need to advertise to John Law.

[Dr. Cranky]

YES! Those are some cool pictures . . .

Thanks for sharing.

[Kodiak Island Modeler]

Actually I was originally thinking of the 60s single and double carb "street type" manifolds that were often found at car shows, but I like the direction this thread is taking. A lot of good information for different eras is already unfolding, so keep the detail pictures and information for all the different set-ups coming. This just might prove quite valuable.

[Steven Zimmerman]

Interestingly enough, Hot Rod or Car Craft did an extensive test several years ago, and came to the surprising conclusion that a dual 4 bbl tunnel ram manifold set up-when used with the proper carburation, cam, headers, etc.when TUNED PROPERLY would out perform any single 4 bbl manifold combination (Not agreein, or dis agreein, just passin it on....)...'Z'

[whale392]

Again, PROPER carburation, cam selection, exhaust, and in a controlled environment. Real world experience trumps lab rats any day, as all sorts of variables play into the equation. Look at Dave and I's experiences with practically the same equipment......two very different sets of results based on the same theoretical data. I have a hearty respect for 'lab tests', but most often than not when subjected to real-world scenarios, they come up short or just plain wrong (just saying).

But then again I digress, I will leave this to the 'experts' to contemplate and ponder on. Read all you want; it isn't even a candle of knowledge to actually DOING it.

(Note: no sarcasm was harmed in the typing of this message)

Edited February 29, 2012 by whale392