Most dry flow port injected manifolds are single plane. This means all cylinders share a common plenum. Dual plane is when an engine is split in 2 where the cylinders are selected by firing order to get equal cylinder filling. If the wrong cylinders are grouped together (like the SLP T-ram intake) then you'll have cylinders running too rich and some too lean depending on the resonance tune.
Resonance tuning is when a pressure wave is going down the intake runner when the intake valve opens.
Resonance tuning is done by changing the volume, diameter, shape, length, and plenums in the system (intake system).
A dual plane intake on a v8 splits the engine into 2 4-cylinder engines. This isn't completely true because the exhaust would also need to be matched which would require primaries crossing over or under the engine.
In anycase, having 2 4-cylinders will build more power at lower engine speeds (give everything else equal) than a single plane intake. The dual plane will also make more power at higher engine speeds but not within an average v8's power range.
Resonace tuning is very powerful in n/a engines, just look at TPI long runners (single plane) making huge amounts of power at low engine speeds.
Here is a little scetch to help understand what I'm talking about.

 

My two cents. Most dual planes have 2 plenums one larger than the other helping spred the power band the smaller one for low end and the larger one for top end. but both lacking in large plenum space and longer runners limmets rpm but promotes good port velocity and will hit revirson(might have spelled that wrong I'm good for that) after 7500 or so.Single planes Have a larger plenum for higher rpm breathing and shorter intake runners. Just a rule of thumb the shorter the runner the higher in the rpm band peak Hp and less fpt. while long runners promote fpt and lower peak power (the down fall of TPI). It is posable to change rpm point in both on some intakes. Cutting a small amount out of the wall and a dual plane will help with higher rpm.Here's some pics of some dual and single plane intakes.

Torker II considered on of the worst single plane intakes out there

 

Torker singlr plane better runners and plunem

 

Victor Jr more plenum and shorter runners with more volume.

 

pontiac proformer bigger plunem for more cubes

 

performer some times has fuel pudling on higher plunem ( note the lines to help this problem on the pontiac above )

 

Actually the torker 2 is better all around than the original torker. The angle of the original is terrible compared to the torker 2 (smooth transisions). The problem with the torker 2 isn't much of a problem but having different length runners will change the resonance tuning. From the looks of it, only by a few hundred RPM but still there none the less.
My reason for posting this thread isn't so much about air flow as it is resonance. I believe the differences in intakes has very little to do with air flow and everything to do with lengths and volumes. It just so happens that we have the choice of 2 kinds of intakes and I'm trying to tell people the physical differences, not just the results.
If you could rev a v8 over 10,000rpm and had the proper cam you would see that a dual plane intake would make more horsepower than a single plane (with everything else equal... plenum volume, runner lengths and dia.).
As for plenum volume, get as MUCH as you can if you're all about making the most horsepower. A general rule of thumb is 1.5 times the engine displacement. So for a 5.0L that's 7.5L of plenum volume (not including runner and head port volumes). That's BIG. The problems with plenums that large is their effect on throttle responce. This is a big problem with wet-flow since there is transport times and other issues involved with slamming open the throttle. So the biggest reason to go with port injection is the ability to make more power with lots of plenum volume with little effect on throttle response (and emissions).
So my recommendation is to fit the largest plenum spacer you can on whatever intake you have, this will make the most horsepower (with the proper tuning).

 

My test motor #3 with the right set up will pull 8700 or so before taking a dump all the dual planes tested have choked the motor bad before hitting 8000, able to see fuel vapors clouds above the carb do to the longer runners resonance. less of a problem on dry flow but a stock tpi will do the same when taken to far out of intended range pushing the fuel up the runners. But what your saying is very interesting. Most of my work is done with carbs and FI gives me fits But something I have to step up to. Most of my testing has shown the Torker better t5han the II and is very close in shape to the victor intakes needing only minor floor changes and a spacer to be an outstanding swapmeet buy.

 

(from the first post)
>In anycase, having 2 4-cylinders will build more power at lower engine speeds (give everything else equal) than a single plane intake.<
..........not quite right..........
Your typical 2 plane manifold will have longer, and smaller
(less cross section) runners,
than a single plane manifold.
That is what helps low end torque, in the 2plane.
..................
The idea about 'multiple cylinder pressure waves', is rubbish.
Just plain negligible.
That said, single cylinder tuning is real, note tpi runners.
Note also, that wet manifold fuel distribution
unequalness, is a real issue.

 

Wow, my head hurts.... Awesome info!

 

The attached image shows some of the designs of the Edelbrock intakes. They represent the majority of intake manifold designs, that's why I choose them.
Keep in mind that these intakes all make power and just because there is a con doesn't mean there's something better out there for your application! The Torker manifolds are very good despite some short-comings that I've pointed out.
Visit http://www.grapeaperacing.com/ for good technical articles that go into greater details.
This thread isn't about making power, it's about understanding HOW to make power but more importantly, WHERE to make power. Any dim whit could bolt together some performance parts and get something to work but it takes some thought to put together a good combo.
Look at the lengths of all of the carb intakes and you can see that they are "tuned" for mid to upper rpm. Also take note that the camshaft is the brains behind the resonance. When the intake valve closes dictates when it returns. The temperature also changes the tuning because resonance it based on the speed of sound which depends on temperature .
My recommendations; 305 or smaller go with either the torkers, the II has it's benifits even though some cylinders will run ever so slightly rich or lean from the others. It's about 1.5" so nothing that's going to result in ANY noticable issues. For larger engines, match up with the victor and have good heads or it'll be a waste of intake (and motor ). The RPM is a great all around middle man since it has runner lengths about equal to the single planes yet resonantes like 2 4 bangers (resulting in lower RPM and super high RPM tuning gains).
The stock TPI intake resonates like crazy at very low engine speeds because of it's long runners. It's matched nicely for a 305 or smaller but anything bigger and the cross-sectional area becomes a bottle neck. I personally like the huge runner TPI intakes with massive plenums. If done correctly long runner intakes would have the flattest torque curve.
I really can't go into much more detail but if you're interested I can recommend some good papers to read. Things like 2nd, 3rd, and 4th tuning where the intake uses the 2nd, and 4th pressure pulse within a typical v8's power band...

 

JP, or anyone.
Do you have info on the cross-sectional area
of the manifold you discussed.
I am interested in that number cuz, CSA , in effect, sets an upper bound on the 'product of CID times RPM'.

 

Do a search for either "Mach index" or "C.F. Taylor" and you will find the relevant posts.

 

Given all that was said here the thing that jumped out at me (and purely by free association) is that each cylinder needs its own cam shaft timing to maximize the air/fuel mixture it could experience. I know it is beyond the scope of price feasibility for the general public, but if the sides operate differently then the operations would be maximized differently as well.

Just a thought,
Jason

 

More food for thought some people try to over come the longer runners on the corner cyclinders with 1.6 rockers.