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How to Install a Bigger Intercooler

Cooling the intake air temperature is a smart improvement for all 5.9L Cummins Engines.

Matt Alesse
Jul 22, 2020
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More than a few automotive hobbyists share the urge to tinker with and modify their vehicles. For some, the projects are centered on second or third cars or trucks, which allows for prolonged downtime and nearly unlimited wrenching until the effort is considered done.
Unfortunately, enthusiasts who don't have that luxury have to satisfy their urge to modify by using their daily driven rigs. That's how things play out for Matt Alesse's regularly used 2001 Dodge Ram 2500. For this ride, minimal downtime and uncompromised reliability are paramount.
Diesel enthusiasts typically handle the fun upgrades first. On older pickups, ECM tuning, bigger injectors, and turbocharger swaps all help increase horsepower and torque to levels the factory never thought were achievable. While the modifications can promote more power and better driving characteristics, they also can expose weaknesses within the rest of the stock powertrain. Transmissions and cooling systems are components that are taxed right away when the wick is turned up.
Parts failures can cause unplanned downtime and extra financial burden. Time and time again, we have seen owners hop up their trucks, and then have to wait to use them after a weak link is found somewhere in the driveline. With Matt's Dodge Ram 2500, our plan is to lay a good foundation for the future, with hope there won't be any catastrophic consequences along the way.
We introduced this project with a report on installing a Signature Series 47RE four-speed automatic transmission from Revmax Converters. The unit is built to withstand 550 hp, and a Mishimoto transmission cooler helps keeps the new unit cool. Why did we overbuild this transmission so much for a truck that currently has stock power output? With plans to upgrade the power on this VP44 injected 5.9, we wanted room to grow. With almost two decades of modifying on this platform, we have learned that failures within stock transmission are inevitable at the high torque numbers we are shooting for.
This installment in our series features Mishimoto's intercooler and tubing kit. We recognize the fact that many 5.9L Cummins-powered Dodge Rams make great power with the stock intercooler, but there are several good reasons why an upgrade should be considered. However, the main justification for making the swap is because the Mishimoto unit is more efficient, plain and simple. With a 47 percent increase in core volume, 50 percent more core thickness, a superior bar-and-plate design, and an air diverter to reduce turbulence and evenly distribute airflow across the core, this intercooler is claimed to reduce intake air temperatures by 25 percent.
Even with a truck in stock form, this is a great upgrade. But when boost levels increase, the intercooler will really shine. In addition to the bigger core, the kit also includes polished 3-inch aluminum piping that we sent to Los Angeles Cerekote (a ceramic-based, baked-on coating that provides great protection against abrasion, corrosion, chemicals, etc.) for colorization. Available in a constantly expanding color palette, we're staying with plain flat black to maintain a stealth appearance.
Tubes are tied with Mishimoto's Duracore technology boots. These couplers are made from five layers of heat-, pressure-, fuel-, and oil-resistant fibers that help prevent blowouts. They are pretty much a necessity at this point, as the stock boots have 280,000 miles and are getting a bit crusty.
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The first thing we need to move is the radiator support beam that covers the intercooler. There are two bolts on the backside that go through the radiator, one directly behind the hood latch, and three bolts on the top and front of each side.
The next major obtrusion is the front bumper. Removal is fairly simple: A few clips on the inner fenders and 3 bolts on each framerail are taken out, and an electrical connector for the foglights needs to be unplugged.
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Upon removing the bumper, we noticed that it has been coming in contact with a recently installed, larger Mishimoto transmission cooler. Since there are no adjustments that can be made to the cooler's position, the bumper is adjusted and modified slightly for sufficient clearance.
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Without disconnecting the lines, we were able to lean the transmission cooler to the side and wire-tie it to a hole in the fender as to not hang it by the lines. The air-conditioner condenser is a bit more rigid when unbolted and must be moved carefully outward and upward out of the way.
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After trying to sneak the stock intercooler inlet and outlet past the radiator multiple times, it is clear that the unit doesn't come out with the radiator in place. The radiator is drained, hoses are disconnected, and then lifted up on each side as we slide out the intercooler.
This side-by-side comparative shot clarifies how much beefier the Mishimoto intercooler is. The only modifications that are required for fitting this unit are small cuts in the inner fenders near the inlet and outlet. The body panel also needs to be bent a few inches outward.
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Some minor prep needs to be done before installing the new intercooler. Supplied brackets are bolted on in order to mount the air-conditioning condenser and transmission cooler. As always, we use antiseize when bolting together dissimilar metals. The rubber mounting bushings from the stock unit also is reused.
Here is the new intercooler installed along with the condenser and transmission cooler. The black intercooler maintains the low-profile stealth look we are going for.
Removing the pipes and clamps is fairly straightforward. The only thing blocking access is the air intake on the passenger side.
While removing the boot closest to the turbo, we found that it has been rubbing against part of the A/C system for quite a while, almost wearing through. We made sure that the new one has plenty of clearance.
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Here is the new passenger-side pipe mocked up next to the stock tube. Doing this helps with clocking and positioning the boot and clamp in preparation for install.
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There are five layers of heat-resistant fibers that make up the Mishimoto boot.


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