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’94-’02 Dodge/Cummins Cold Air Intake System
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With the great customer satisfaction and success of the 3rd Generation Dodge/Cummins cold air intakes, numerous requests for a similar kit from 2nd Generation owners prompted PSM to research, develop, test and perfect a cold air intake that is totally different from our competition. The 2nd Generation air box is exposed to severe heat radiating from the close proximity of the turbocharger and exhaust manifold so the importance of getting colder intake air to the turbocharger was critical. Of all the different air intake ideas PSM considered and tested, the idea that delivered the coldest air and reduced the air box air flow restriction the best was also the simplest. Our Cowl Duct air intake provides the coolest air to the turbocharger while retaining the factory sealed air box and is the only commercially available “true cold air” intake that is tested and proven to provide cooler air to the turbocharger and engine.
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Description | Major Benefits | Specifications | Installation | Test Results | Price & Shipping Info
With the installation of the Cowl Duct air intake, additional cold air is delivered to the stock “sealed” air box through a duct located between the air box and firewall. Cold air is picked up at the high pressure area located at the base of the windshield which then enters through the cowl and into PSM’s variable diameter “S”-shape duct leading to the stock air box. This duct enters the back side of the air box below the air filter. The existing factory fender air inlet opening and snorkel is retained to prevent hot under-hood air from entering the air box.
- Lower EGT: Cooler intake air is denser which allows the engine to make the same power with less fuel. Less fuel in the combustion chamber will result in lower exhaust gas temperature (EGT). An EGT reduction of 40-50°F is not uncommon when additional cold intake air is delivered to the factory “sealed” air box through the Cowl Duct intake. Since cooler intake air lowers EGT, more fuel can be injected into the combustion chamber to increase power and still remain below the maximum recommended EGT.
- Lower intake air temperature for more power: Intake air temperature inside the air box is an average of 7°F cooler than using the OEM snorkel alone, resulting in 1.5% more power. Most aftermarket heat shield type air boxes have an intake air temperature at least 40°F hotter than stock resulting in a 6.5% power loss under heavy load full throttle applications. Cooler air intake temperature results in an increase in air density and allows your Cummins to make more power when racing and towing heavy trailers or loads.
- Lower intake air flow resistance: Increasing the air inlet opening into the stock air box by providing an additional side inlet, results in lowering the air flow restriction through the air box by 33%. This allows the turbocharger to respond to throttle changes quicker, resulting in faster turbocharger spool-up, better boost response and increase boost pressure to provide up to 4 horsepower gain at mid-range and top end. The air filter minder will now remain “out of the red zone” under full throttle operations.
- Faster engine cool down: The Cowl Duct intake uses air from outside the engine compartment, which results in lower under-hood temperature and faster engine cool down prior to shutting down an engine compared to any other aftermarket air intake
More Benefits
- Lower under-hood air temperature: The engine, radiator and especially the exhaust manifold and turbocharger are the 4 biggest contributors of under-hood heat. When using cooler intake air in the engine, the exhaust manifold and turbocharger produces lower EGT, thereby radiating less heat into the engine compartment. Lower engine compartment temperature extends the life of plastic and rubber components under the hood.
- Reduce air turbulence: Flat panel air filters are known for straightening air flow as air passes through the filter, resulting in uniform air flow and a shorter air path to the turbocharger. Conical air filters, due to their round shape, swirl the air as it travels through the air filter and down the intake tube (just like water vortexes when a toilet is flushed) increasing air flow turbulence. Turbulence in the intake tube causing the turbocharger to work harder to draw in air.
- Supports larger turbochargers: Bigger turbochargers supply more air to the engine. The Cowl Duct intake will support enough air flow for most single turbocharger applications on the Cummins. During our testing, air flow choking started at over 1100 cubic feet per minute with excess of 50 psi of boost which is sufficient to produce over 650 horsepower.
- Air filter remains cleaner: Semi-heat shield air box allows under-hood heated air, circulating around the engine to enter the conical filter, depositing an oily and greasy film on the filter, resulting in more frequent filter cleaning to maintain performance. The OEM sealed air box prevents engine compartment air from entering the air filter, keeping the filter cleaner and extending the replacement or cleaning intervals.
- Fuel mileage increase: Increased power gain from cold intake air may permit the engine to remain in high gear or converter lockup during hill climbing resulting in better fuel mileage.
- Factory appearance: The Cowl Duct intake retains the OEM air box to provide that unmodified functional appearance.
- Corrosion resistance: The Cowl Duct intake is constructed from silicone rubber that will not rust or turn color.
- Engineered to Perform: PSM is known for thoroughly testing their products for performance, durability and reliability. Whether it is on the dynamometer or in real-world testing under all climatic conditions, our products are proven to perform. We offer a money back guarantee if our air intake does not provide more cold air to the turbocharger and engine than any other aftermarket intake.
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- Exclusive custom engineered “S”-shaped elliptical/round duct is manufactured from silicone rubber reinforced with 5 layers of fabric with a spirally wound 0.039-inch diameter stainless steel wire. Duct is rated at 40 psi positive pressure and 1 psi negative pressure with a maximum 500°F operating temperature.
- Vinyl/plastic edge trim reinforced with metal insert to hold shape and provide strength.
Installing the duct into the cowl will require a 3-⅜-inch diameter hole to be cut through the firewall. A template is provided to locate this hole. Cutting the hole can be performed using a hack saw, Dremel-type tool or a hole saw. The vinyl/plastic edge trim is installed over the cut metal edge to protect the cowl duct. Use the elliptical hole template to scribe the hole in the side of the air box. Cut the hole using a keyhole saw, Dremel-type tool or a file. Removing and re-installing the OEM air box is done using common automotive hand tools. Our cold air kit come complete with cowl duct, edge trim, (2) hole location templates, screencloth, and detailed instructions with pictures.
- Intake air temperatures inside the air box while climbing a 6% grade for 4 miles: Stock vs. PSM Cowl Duct vs. heat-shield air box. See Intake Air Temperature #2 Test
The purpose of this test was to verify if engine compartment heat has an effect on intake air temperature when comparing different types of intake air box designs. Intake air temperature from the sealed OEM air box was compared to an aFe semi-open heat shield type air box. The test was set up to simulate a long pull up a steep grade on a hot day, but can be applicable for extreme engine loading conditions as drag racing and sled pulling.
The truck for this test was a 1995 2500 Dodge with the 180 horsepower Cummins, 5-speed manual with a 3.54 rear end. Truck test weight was 10,500 pounds, traveling at a constant speed of 60 mph in 4th gear up a 6% grade for 4 miles. The truck is completely stock except for the air intake changes made during the test runs.
Test instrumentation included one temperature sensor located next to the front headlight to record ambient air temperature. Another sensor was located inside the air box just prior to the intake duct to record intake air temperature, and the 3rd sensor was placed outside and in front of the air box to record under-hood air temperature.
The highest under-hood air temperature and the highest average and peak (135° F) intake air temperatures occurred when using the aFe semi-opened heat shield air box with a conical air filter. This air box took in considerable amount of hot under-hood air causing the intake air temperature to raise significantly above (up to 27°F higher) the sealed OEM air box. Air density loss from 27° F hotter intake air equates to a 5% loss in power. For example a 235 horsepower engine would produce 223 horsepower. The sharp rise in intake air temperature, at the beginning of the test and again starting at test mile 2.25, was due to the engine working harder to climb the steeper sections of the 6% grade.
One modification owners make to the OEM air box is to remove the rectangular snorkel between the air box and fender in anticipation of getting more air into the box. From the graph, we find that more air does get into the air box, but this air is hot due to under-hood air temperature ranging from 145 to 155° F during the test. Consequently intake air temperature rose between 115 to 118° F, which is 10° F higher than the OEM air box intake temperature. This higher intake air temperature will cause a 2% loss in power due to the decrease in air density. Consequently, there is no gain (actually a loss) in power when the snorkel is removed from the stock air box.
The Cowl Duct force-feeds the stock air box with cool high pressure air from the base of the windshield causing intake air temperature to drop up to 9° F lower than the OEM air box intake temperature. This lower air intake temperature will increase air density and engine power by approximately 1.5% or 4 horsepower for a 235 hp engine. From the graph, note that the Cowl Duct was the only intake where intake air temperature closely followed ambient air temperature.
Preventing hot under-hood air from entering the air intake is vital in making additional power, lowering EGT, reducing under-hood air temperature and engine cool down time. Currently, all automotive diesel truck manufacturers use a “sealed” air box where the fresh air inlet to the box is 100% sealed from the engine compartment to ensure that the coldest intake air comes from outside the engine compartment. The only downside in using a sealed air box is the small size of the air intake opening to allow air to enter the box. With the installation of the Cowl Duct, PSM corrected this problem by creating another opening in the side of the OEM box to supply the box with additional cold air.
The OEM plastic air box is a good insulator in keeping the air cool inside the box. The thermal conductivity of plastic is 22 times less than steel. Why would anyone want to use a steel air box? PSM believes there is no better air box available than the OEM plastic “sealed” box with the factory snorkel in place between the air box and fender. The addition of the Cowl Duct to the OEM air box greatly enhances the performance of this box.
Intake manufacturers apparently do not test for intake air temperatures and if they did, they would almost certainly not disclose how much hot air their systems provide to the engine over and above the OEM air box. Unfortunately, manufacturers appear more interested in providing the customer with high air flow numbers that are obtained from laboratory tests and not from any testing done on the truck. These CFM numbers are meaningless and misleading and no longer apply to their intakes once installed in the truck.
For customers who want the best performance from an air intake, PSM is proud to offer the Cowl Duct cold air intake.
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- Dynamometer test with 135°F under hood air temperature: Stock vs. PSM Cowl Duct vs. heat-shield air box. See Dynamometer #5 Test
The purpose of this test was to document the effects engine compartment heat has on power produced from a sealed OEM air box with and without the Cowl Duct installed, and compare these results to a semi-open heat shield type air box. This test was set up to simulate real-world driving conditions with under-hood air temperature that typically exceed 150° F under extended high engine load conditions. See Intake Air Temperature #2 test.
The test truck was a 1999 2500 Dodge with a modified Cummins engine, automatic transmission and a 3.54 rear end. Performance enhancements include an Edge Comp box, ATS Aurora 2000 turbocharger, Arc-Flow intake elbow and Pulse-Flow exhaust manifold, 100 hp injectors and a FAST fuel pump. The air intake was stock.
The truck was tested on a Mustang MD-1750-DE dynamometer with a 10-second duration “sweep” to generate the power curves. The hood was closed for all tests. A sensor was located next to the air box to monitor under-hood air temperature. The vehicle was run without load until under-hood temperature reached 135° F, at which time the dyno test was initiated. A high power fan was used to blow cool air onto the front of the vehicle during all test runs.
The semi-open heat shield air box allowed the truck to make 3 less horsepower than the OEM box at the start of the test due to the loss in air density from the air box taking in hot under-hood air. At maximum power this air box made 5 less horsepower and13 lb-ft less torque than the OEM air box. Note the slower turbo spool up (due to the loss in air density) compared to the OEM box. The semi-open heat shield air box made an average of 13 less horsepower and 29 lb-ft less torque than the OEM box between 2000 to 3000 rpm. Why pay $250 or more for a semi-open air box that makes less power than the OEM box in real-world driving situations!!!
With the Cowl Duct installed, the air box allowed the truck to make more power than the OEM box throughout the rpm range since cold air was now taken from outside the vehicle in addition to the factory fender area. Faster turbo response and spool up was improved due to the increase in air density and less air flow restriction in the air box. At maximum power, the Cowl Duct made 3 more horsepower and 6 lb-ft more torque than the OEM air box. The Cowl Duct air box made an average of 4 more horsepower and 11 lb-ft more torque than the OEM box between 2000 to 3000 rpm.
When the test was re-run with the hood open (not shown) and 86° F under-hood temperature, the semi-open heat shield air box again made the least power at 386 hp and 799 lb-ft torque. The OEM air box produced 391 hp and 818 lb-ft torque. The Cowl Duct air box made the most power with 494 hp and 815 lb-ft torque.
On a stock 160 to 235 hp engine, expect power gains from the Cowl Duct to be ¼ to ½ less than the above numbers.
Dyno testing the Cowl Duct can not duplicate the benefit of increase in air density from high pressure cool air entering the air box when cruising on the highway. However, we can calculate from the observed reduction in air temperature and pressure drop inside the air box, that one can expect another 4 horsepower and 8 lb-ft of torque (above these dyno numbers) from the cowl duct when traveling at 60 mph.
Aftermarket air intakes do not increase air flow. See air filter Dynamometer #6 test for detailed explanation. A good intake box should have less air flow restriction than the OEM box once it is installed in the truck. Testing intakes on a flow bench in free air is ineffective and misleading. Intakes need to be tested in the engine compartment. Our Cowl Duct, once attached to the OEM air box and tested in the truck, reduces air flow restriction by 3” water column pressure below the OEM box at maximum rpm and boost. Lower air intake restriction allows the turbocharger to work less to draw in air and have more energy remaining to make more boost.
The power gains shown in the graph when using the Cowl Duct may appear minimal, compared to other manufacturer’s hype, but these are real numbers, not created and unsupported like the outrageous claims made in advertisements. Beware of manufacturer’s inflated high horsepower and torque claims at low to mid-range rpm from altered dyno test procedures.
Engine compartment heat does have a detrimental effect on maximum engine power. This effect can be minimized by selecting the correct intake air box. Sealed air boxes will always outperform semi-opened heat shield type air boxes in real-world driving conditions because they keep out engine compartment hot air. Most if not all aftermarket air boxes permit hot under-hood air to enter the air filter, causing a loss in air density and power.
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’94 to ‘02 Dodge/Cummins Cowl Duct intake is available in BLUE or BLACK:
$109.00 plus $10.00 shipping
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