CFM+ (CFM PLUS) Dodge Intake Manifold

Regardless of which tuner, air filter, exhaust system or aftermarket intake you may already have, you need to dramatically increase your air flow. No other aftermarket intake comes close.

Even without a computer it's easy to see why the CFM+ flows so much better than the angular stock aluminum manifold with its nearly 40% flow restriction at the front mounting bolts. (Fig. 1)

But why does the CFM+ flow so much more air than the other oversized cast aluminum manifolds in the market and maintain lower air temps?

There are a number of reasons we will discuss:

1.) The very large center section of the competitor cast aluminum manifold may look impressive but it is very bad for flow. The inlet to the manifold from the inter cooler and the outlet of the intake manifold into the engine are very similar in cross-sectional area so when the center section is over three times larger than the inlet and outlet the air flow slows dramatically through this center section. The air flow then is forced to speed up to exit. This causes turbulence in the flow, leading to pressure drop or pumping losses.

2.) The competitor's manifold is so oversized in the center section that two of the mounting fasteners which hold the intake to the engine had to be changed to long bolts or studs that must pass directly through the air flow.(Fig.2) This causes tremendous turbulence in the flow leading to additional pressure drop or pumping losses.

3.) You can also see in the picture of the cross-section of the competitor aluminum manifold there are two surfaces (Fig.2) protruding down into the flow path that create recesses into the outside surface of the manifold.  These pockets allow the mounting nuts to look good recessed on the outside but cause a big problem on the inside where it matters. (Fig.2) These two surfaces protruding into the air flow act to trip up or tumble the air flow. Again this causes additional turbulence in the flow leading to pressure drop or pumping losses.

4.) Cast aluminum has a much rougher surface than the advanced technology composite CFM+ manifold. The rough interior surface of the competitor's cast aluminum manifold causes additional turbulence.

It should now be evident why there is a 44% increase in air flow over stock and a 20% increase over the cast aluminum manifold of the competitor. These tests were performed on a SuperFlow model SF-1020 Probench.

Changing to the CFM+ over the competitors cast aluminum aftermarket manifold gives almost the exact benefit as replacing your heater grid with a free flow spacer.

5.) The volume of air that can get stuffed into the engine is also greatly affected by the density of the air flow. This is why the material the manifold is made of is so important. If the manifold's material acts to insulate the hot under the hood air from reheating the air flow that has just come out of the inter-cooler that is a very good thing for maintaining air density but if the material readily conducts heat such as aluminum that would be bad since the hot under hood temps would raise the air entering the engine since under the hood temps are by definition higher than ambient or outside air temps and heat flow is always from high to low temp. A materials ability to allow heat to pass through it is called its Thermal Conductivity represent by k in engineering equations. Aluminum has a Thermal Conductivity rate or “k” of 236 W/M-oK. The CFM+ composite material's Thermal Conductivity rate is, 0.25 W/M-oK , which is 944 times lower.

 Also the oversized cast aluminum intakes present more aluminum surface area that absorbs more under the hood heat and transfers it into the air flow.

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