Giving any engine's air intake and exhaust tract a clearer entry (or exit) path is key to making more horsepower. In fact, it's very basic knowledge that any vehicle's air intake and exhaust system should be upgraded before any internal power-adders are installed. The benefit of adding more bolt-on, go-fast goodies to your diesel's performance résumé is that you can also use it as an opportunity to dress up the engine a little. Over the holidays we did just that to our '02 Dodge Ram 3500, affectionately known as Project 24-valve. We installed an exhaust manifold from Performance Diesel Inc. (PDI), an intake elbow from CFM Plus, and a red valve cover from Hoesli Diesel Service. The best part: In just a few short hours, our improved intake and exhaust components added more show and go to the 5.9L Cummins. First, we added this red valve cover (PN 3943668) from Hoesli Diesel Service for just $158. It's sort of a tribute to the red valve cover used on the high-output N14 Cummins engines offered in big rigs from the factory. We think it's the perfect indication that our 5.9L cousin has been turned up. First, we added this red valve cover (PN 3943668) from Hoesli Diesel Service for just $158 We disconnected both positive battery cables to prevent shorting out the intake heater grid while replacing the intake elbow. We disconnected both positive battery cables to prevent shorting out the intake heater gri As you can see, the CFM Plus elbow (PN 10-002-305) provides a much smoother path for air to flow into the engine. In fact, CFM Plus claims its elbow flows 40 percent more air than stock. The intake elbow came with both (upper and lower) intake gaskets for the grid heater, an angled intercooler boot (required on '981/2 to '02 Cummins engines), and all hardware to complete the install. In addition, the backside of the elbow had three ports, which come drilled, tapped, and plugged for any injectables we may want to run in the future (we used the center port for our boost gauge). As you can see, the CFM Plus elbow (PN 10-002-305) provides a much smoother path for air t This is why the supplied angled intercooler boot is necessary. It simply bridges the gap and mates the intake intercooler plumbing to the bottom of the CFM Plus intake elbow. Once it was finagled into place, the boot was secured with our spring-loaded boot clamps. Our advice: leave the clamps off the boot, fit the boot on the intake elbow, put two of the supplied nuts on the intake elbow to keep it from moving, and then manipulate the boot until it feels snug. This is why the supplied angled intercooler boot is necessary. It simply bridges the gap a Next, we moved on to replacing our second-generation Dodge's exhaust manifold with PDI's three-piece unit (PN 346424V). PDI's 24-valve exhaust manifold is made from a high-nickel-content silico-molybdenum ductile iron, which is the same material used to cast turbocharger housings. We recommend replacing each exhaust manifold gasket (Cummins PN 3946275) and the flange gasket (Cummins PN 3901356) when doing a job like this for the best seal possible. We got our gaskets from Scheid Diesel. Next, we moved on to replacing our second-generation Dodge's exhaust manifold with PDI's t Once the air intake was removed, the oil line for the turbo was disconnected, followed by the lower turbo clamp, the turbo oil drain tube where it mounts to the engine, and even the oil filter (for utmost wiggle room). From there, the turbo flange bolts were loosened (top of flange), as were the nuts on the bottom of the flange (the stock flange has two studs in the bottom, but the PDI manifold comes with four studs). Once the air intake was removed, the oil line for the turbo was disconnected, followed by With the turbo out of the way, we disconnected the EGT probe from the stock exhaust manifold, pulled the water line running to the heater core out of the way, and removed the 12 exhaust manifold bolts with a 13mm socket. With the turbo out of the way, we disconnected the EGT probe from the stock exhaust manifo Once the stock exhaust manifold was off the engine we compared the two. It was obvious to us that the PDI unit's exhaust passages offered smoother bends, and its ports (especially the center two) were more open than the choked-down ports on the stock manifold. This clearer path to the turbo leads to quicker spool-up and lower EGT. Once the stock exhaust manifold was off the engine we compared the two. It was obvious to In order to obtain the smoothest possible mating surface for the new exhaust manifold gaskets, we used an angle-grinder with a 3M Scotch-Brite pad to clean up the area surrounding the exhaust ports on the cylinder head. In order to obtain the smoothest possible mating surface for the new exhaust manifold gask A Cummins exhaust manifold isn't exactly a lightweight component to maneuver, so don't be afraid to climb aboard in an install like this. With the turbo out of the way, a surprisingly comfortable fenderwell seat can be utilized under the hood of a second-gen Dodge. We started installing the PDI unit by putting the centermost exhaust manifold gaskets and bolts in first. And by not tightening the center bolts all the way, the manifold was not only supported, but enough room was left over to manipulate the other four gaskets and fasteners into place. A Cummins exhaust manifold isn't exactly a lightweight component to maneuver, so don't be PDI supplied four centersection bolts, washers, and lock washers with its exhaust manifold (the top two are shown). The supplied centersection bolts require a 5/16-inch Allen head socket in order to install them. The rest of the manifold was bolted into place by reusing the factory 13mm head bolts. Then, starting from the centersection out, each bolt was torqued to 55 ft-lb in a clockwise manner. PDI supplied four centersection bolts, washers, and lock washers with its exhaust manifold Next, the supplied flange studs were installed, followed by the new flange gasket and the turbo. Note: '981/2 to '02 engines using the stock turbo will require owners to drill out the tapped holes in the turbo flange with a 7/16-inch drill bit in order for the studs to go through. We didn't have to do this because our aftermarket S300 turbo's flange was already tapped for use with flange studs. After our turbo and all other hardware was reinstalled, we took the truck for a 15-minute testdrive, then returned to the shop and re-torqued the exhaust manifold bolts once again to the recommended 55 ft-lb in a clockwise manner, starting from the centersection outward. Next, the supplied flange studs were installed, followed by the new flange gasket and the SOURCES CFM Plus 1451 Engineer St Suite B Vista CA 92081 760-598-2478 http://www.cfmplus.com/ Hoesli Diesel Service 5716 E. Morgan Ave Evansville IN 47715 812-473-5604 www.hoeslidiesel.com Scheid Diesel 4960 North 13th St Terre Haute IN 47805 800-669-1593 www.scheiddiesel.com Performance Diesel Inc. 687 N. Industrial Rd. Saint George UT 84770 800-511-1231 www.performancedieselinc.com By Mike McGlothlin Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!