For those who don't remember the Edelbrock sp2p it was based on the 180 degree firing order of a conventional dual plane only it had (smaller cross section) individual runners to each plenum with not shared "criss cross" plenum intersection between the left and right banks.

The concept was to improve torque and fuel efficiency (high velocity cylinder filling for near peak VE) at high load/low engine speeds during the early 70's gas crisis.

The trouble was, from a performance standpoint the individual port runners were too small to feed the engine very well at higher engine speeds.

I have always wondered if the same architecture would work very well today with modern port design/cross sectional area and flow with positive taper toward the plenums (like a modern Single plane) with the added benefit of modern fuel injection. It seems this type of design would smooth out the induction pulses (signal to a carb) and eliminate the low RPM cylinder to cylinder "robbing" that goes on with conventional single or dual plane manifolds.

I also can imagine the center divider that could retract up and down into the plenum floor at High RPM (utilizing EGT closed loop tuning software in order to optimize HIGH RPM power, similar to the V-boost system used on the old Yamaha V-Max V-4 motorcycle engines (ihad one back in the 90's lol). Either via a vacuum transducer or even a small servo motor. I cant imagine the intake being much taller than a conventional Dual Plane.

This technology is relatively inexpensive today even though this was "Buck Rogers" back in the 70's

Anyway, just thinking out loud. I always thought it was a cool concept. I always wanted one to play with and maybe to put on a super fuel efficient 273 or max port one for a 318 or even a 360 torque motor.

Of course ....if it was or became a good idea worth developing, I'm sure it would be mass-marketed to the bowtie boys long before we would ever see one!

I know there a lot of creative minds out in moparts land way smarter than me, so please feel free to comment!!

My thinking is that the only time it would significantly help TQ would be around 1000-1500 RPM, in order to take advantage of it you would need a very tall rear gear and a manual trans as no TQ converter and auto trans will hold the RPM that low.

It really seems as though modern engine designers have gone the opposite direction with a even a 345 CID engine coming from the factory with huge ports that flow well over 300 CFM at pretty low lifts.... keep in mind they are chasing every tiny bit of MPG they can find as well. I really do think the ship has sailed on that manifold unless you build your engine and entire car around extremely low RPM something that never goes over 3000 RPM. I think MPFI negates that even more because you can fine tune cylinder to cylinder A/F ratio and still atomize the fuel really well at very low air speeds.

I got you Dave but imagine if the same design concept could be reworked with properly sized ports for modern head flows and high rpm, so you would basically have a dual plane at low/mid range and essentially a tunnel ram (or a very good single plane) up top.

In this day of strokers and TBI though you are right, theres easier ways to skin a cat.

I ran one a smog 440 for a couple of years with tbi, it ran pretty good for the most part but, wow did it nose over above 5,000 RPM. It would definitely be interesting to see the design opened up to as large as possible within stock port cross section like you mentioned. It would probably be the best dual plane ever made When was the last time a new dual plane intake was released? The Performer RPM?

I agree, it would be easier to build a 505" with Trick Flow 270's and their intake with fuel injection and make even more power and torque that hangs on for awhile

But we’re talking torque and gas millage not HP. A lot more options for 4500 and above

I worked with a racer in the early '70s who was into velocity over volume for smaller engines.
Sounded logical, and better yet, it worked.
Applied the same thinking to the 1st Edelbrock SBC tunnel ram - the one that was a big box - on a '57 Vette drag car, because its 331/327 was so lazy.
Filled a bunch of that box's interior cavity, and the car picked right up.

Just like a garden hose, no nozzle and water flows ok maybe shoot out 4-5 feet. Put a nozzle on it to the small fast stream and it shoots out 10-15 feet with same pressure-volumn. OR like an air foil (wing) slow on the bottom fast on top (lift). Of course air can get too fast and it slams into the outside of a corner (can’t turn, one of the laws of motion) slow the air down it makes he turn. Hellcat at 150 mph or 50 mph, no tires sliding.

When I think “plenum volume” my next thought is: how big does plenum volume has to be to keep the pulses from the closing of one cylinder’s intake valve from traveling backward to the plenum and interfering with flow to some other cylinder.

Intake manifolds are much more like “church pipe organs”
than that of several smaller water pipes branching off a big main water pipe.

When I think “velocity” my next thought is peak torque will occur when “momentum” of the air (its mass multiplied by velocity) is at the optimum level that air will continue to fill the cylinder even after the piston has reached dead bottom and begun to rise. “Common sense” would falsely lead one to believe that a rising piston will push air back out of the cylinder but science reveals that momentum can “shove” more air in for a short time. This “shoving” can be as violent as the way rock concert goers can be killed by the “crush of a crowd.”

Beyond that momentum effect, away from the intake manifold, the most important velocities discovered in the last 35 year has been the speeds of “swirl” and “tumble” in the air fuel mixture when the piston is approaching top dead center. Since the spark is going to occur 10 to 40 degrees before top dead center the swirl and tumble velocities in that range helps ‘fast burn.” However the internal shape of intake manifold cylinder runners can begin the “swirl.”

The advantage of the 180 SP2P concept, in my mind, is the fact that each runner is directly connected to the plenum half without having to share that common 'Left-right' crossover branch (of a typical dual plane) which is effectively a Half-plenum.

So you can keep the pulses (cylinder draw) completely smooth and balanced.

I always though the basic concept was sound, it was just applied/targeted to too narrow of a powerband.

So if you made an SP2P design a high rise with port cross sections an plenum volumes comparably bigger than say an Air Gap RPM the pulses and flow to the valves Could actually be stronger and less turbulent (smoother) than either a dual plane or a single plane.

The greatest advances in manifold design since the 70's have been more related to runner taper which effectively acts like more charge plenum and (in a way) a 'check valve' that speeds the pulse on the way toward the valve and reduces the velocity of the reflective wave on the way back to the plenum.

I just always found intake manifolds fascinating I remember reading all the Jenkins and Smokey Yunick articles back when I was a kid. When I got my ported BB '337 manifold back from Larry Smith (DAYTONA 500 winning Engine Builder) I sould actually see (and feel) the science he put into the porting.

at one time, i was goofing around with a single plain torquer intake.
after mating the intake to cylinder ports, i made a series of divider plates that separated the intake into right and left half's.
these plates had different sized "cut outs" that [possibly ?] could allow each cylinder to take as much as they wanted/needed. [?]
the object was to swap the plates to see which shape was best, but i never installed the intake on anything to find out just how much time and effort was wasted..........[or not]