Making power with diesel is pretty straight forward. Since nearly all of the powerplants are turbocharged, it only becomes a matter of turning up the wick a little. More air, more fuel and you're making power. Aftermarket intakes, exhaust systems and programmers have taken the guess work out of making more power with diesels. Exhaust gas temperatures (EGT's) and the ability of the rest of the drivetrain to handle the new-found power become the limiting factors.

For the most part, the factory engine components can handle these upgrades, provided things don't get too extreme. However there are subtle ways to improve an engine's efficiency when these upgrades are applied, especially on the 1998-2007 5.9-liter Cummins powerplant.

Improved airflow on the Cummins can be as simple as an intake manifold change, and Fastcore has come up with an easy, bolt-on, composite replacement manifold that not only improves airflow, but also drops exhaust gas temperatures, according to the company. Their CFM+ intake manifold is computer designed using advanced 3D solid modeling technology and has been thoroughly tested on a SuperFlow flow bench for optimal airflow and efficiency.

By using high strength composite materials, instead of metal, the CFM+ intake reduces under hood thermal conductivity, allowing for better air density and consequently, lower EGTs when towing, Fastcore says. Compared to the stock intake manifold, which necks down at the engine to clear two mounting bolts, the CFM+ manifold offers no obstructions which create air turbulence and consequent pumping losses, flowing 40 percent more air than the factory intake manifold. The CFM+, thanks to its composite construction, also offers a smoother, more streamlined air path for improved performance.

Installation is so simple, a company representative was able to bring a stock Dodge Cummins to our Orange, Calif. offices and do in the intake swap in the parking lot, utilizing ordinary hand tools, in less than a hour. While he admitted you'd be hard pressed to see any dyno gains with just an intake swap on a stock truck, he added that it's a great place to start since it reduces EGTs under load and enhances the effects of any other bolt-on modification such as an air intake, exhaust system and programmer.

If you own a late-model Cummins and wonder where to start with aftermarket upgrades, improving engine efficiency with a CFM+ intake manifold might be a good place to start.

1. Fastcore's CFM+ intake manifold comes complete with all the necessary mounting hardware and complete instructions. It is also available in either a black powder coated finish or this cool carbon fiber finish.

2. Here's some comparison shots between a stock Cummins intake manifold and the CFM+ unit. Besides the obvious size difference, and larger opening to the engine, the CFM+ also boasts smoother radius for improved air flow. The composite construction is also said to reduce thermal conductivity over metal manifolds.
3. Here's what the stock manifold looks like on a stock 24-Valve Cummins.	4. The install begins by removing the bolt that holds the dipstick in place.	5. On this truck, a plastic pin holds a wiring harness on the back of the manifold. Remove the pin and move the harness out of the way.
6. Loosen the hose clamp on the boost inlet line.	7. Next, unbolt the four bolts that hold the intake manifold to the engine.	8. Carefully remove the factory intake manifold, being careful not to drop debris into either the engine or boost hose.