Dual Plenum vs Single Plenum

[olsonjus]

I have been getting a lot of interest in this intake manifold along with many requests to produce a "Dual Plenum" intake manifold. I've been doing some research and came up with the following data supporting a single tappered plenum:




Here is some flow testing that was performed on the above manifold:

Virtual Works
--------------------------------------------------------
Cylinder 1 - 334.2
Cylinder 2 - 333.9
Cylinder 3 - 334.7
Cylinder 4 - 334.1
Cylinder 5 - 334.6
Cylinder 6 - 334.5

Average - 334.33
Variance cylinder to cylinder - 0.2%
Efficiency - 92%

My question after seeing these flow numbers is there really a need for a dual plenum manifold? What is to be gained by doing so if you can get such consistent flow cylinder to cylinder with a tappered single plenum?

[Greg_S]

Thats pretty interesting, how much does it cost to have the testing done?

[Billman]

Sure the Tapered is very good when the air comes with a nice flow, but after the intercooler and some bends will the air have also that nice flow to all cylinders?? I think the Dual plenum has the ability to overcome this issue!

[A1QSHIP]

A question I have about how it was tested. It appears from the picture that a vacuume is being applied to the outlet of the port runner and flow is being measured via the cfm flowed. Can an accurate data value be extrapolated for boost pressure flow rates from this method? If one wanted to test the per cylinder boost pressure value rates should not a pressure be applied to the throttle body side of the intake manifold?

[volcano rs]

whats the maximum power you can get out of a rs2 inlet manifold?

[olsonjus]

Here is the power that has been made with the above manifold on 6 cylinder supras:

[olsonjus]

We live in an atmosphere of 14.7psi. Raising the pressure differential across the port will only increase flow numbers. Most all flow benches operate under vaccuum from 10" h20 all the way up to 120" h20. I've never seen one operate the other way around with a pressure applied to the inlet of the port.


Regards,
Justin Olson

[A1QSHIP]

We live in an atmosphere or 14.7psi. Raising the pressure differential across the port will only increase flow numbers. Most all flow benches operate under vaccuum from 10" h20 all the way up to 120" h20. I've never seen one operate the other way around with a pressure applied to the inlet of the port.

Well, exactly my question. Are the values for flow generated by a vacuume a valid measurement for an intake manifold under pressure?
Thanks, Chris

[olsonjus]

Well, in reality naturally aspirated motors run under vacuum. The intake valves open as the piston is desending in the bore, and it creates a pressure differential between the cylinder and the intake port. This delta P is what draws air into the engine. Turbocharging a car simply raises this pressure differential.

Regards,
Justin

[Sweeper]

The biggest problem with S2 manifold and reverse MTM manifold is the 1st and 5th cilinder air recieving , am i right ?

[Lupo911]

no Sweeper, thats not right... thats only a Problem with ths stock Manifold over 1.6 bar on the 5 Zylinder...

[Greg_S]

no Sweeper, thats not right... thats only a Problem with ths stock Manifold over 1.6 bar on the 5 Zylinder...

I understood it was the standard exhaust manifold that was restrictive on 1 & 5

[Jamo]

Anybody else got any comments on dual vs single plenum manifold?

I see Jeffer has post that a single tappered is good enough and dual is not really required.