When we last left our Project 12-Valve Dodge, it was making a little over 300 horsepower at the rear wheels, but exhaust gas temperatures hadn't dropped as much as we had hoped. We were looking for EGTs in the 1,350 range, and instead were at 1,450-1,500. We'd talked to a few people who told us that the stock intercooler was a restriction, so we decided to test that theory by installing a new "Cool-It" intercooler from BD Diesel Performance. It was our hope that we could get some more power through cooler, denser air and also keep our EGTs from getting out of control. In order to duplicate real-world driving conditions, we also did a tow-test simulation, where the load dyno at Imler Diesel was used to simulate the stress of an 8,000-pound trailer up a 6-percent grade. This way, we could not only measure peak power, but see how our new intercooler stacked up under a severe load.
Baseline TestIn our initial test, we tried the tow simulation at 70 mph, but the truck's EGTs quickly climbed out of control, and the test had to be stopped. For those wondering, continuous 1,200-degree exhaust gas temperatures are safe for towing, while 1,400 degrees may result in melted parts, so there isn't much of a spread. With the tow test at 65 mph, our EGT was hovering at an uncomfortable 1,350 degrees, and it took a light foot to keep it that way. We also had a heat gun on the intake-side intercooler tank, and registered 151 degrees F during the two-minute test.
With the new BD intercooler installed, we first checked peak power numbers to see what it had gained. With the stock exhaust still in place, we registered 321 hp-about 20 hp better than our previous best with the factory muffler installed. We checked out the EGTs, and we got a 100- degree drop down to 1,400 with the new intercooler. next up was the tow test, and that is where we were surprised. In the same two-minute test, we went from a piping-hot 1,350 degrees to a more-than-safe 1,100 degrees. In addition to the incredible 250-degree drop in exhaust gas temps, we were also able to modulate the pedal more, and tow at 70 mph instead of 65. Intake temperature also dropped from 151 degrees to 88-a 63-degree drop in intake temps, and only about 10 degrees above ambient.
All in all, we were very impressed with the BD intercooler. While we did gain an additional 20 hp and a 100-degree drop in EGTs during our dyno test, the big news was the tow test. If you tow (and we know a lot of you do), you'll be glad to know that the 250-degree spread between stock and aftermarket took us from a borderline-burnt-parts 1,350 to a completely safe 1,100, in addition to helping us tow faster, which is a big success in our book.
 At first, we measured intake...  At first, we measured intake temperature at the engine intake, but found out that heat from the motor interfered with our readings. Measuring at the front of the driver-side intercooler tank turned out to be much more accurate. |  In comparing the stock intercooler...  In comparing the stock intercooler with the BD model, we noticed that it was thicker and taller than the restrictive factory piece. |  The BD intercooler also had...  The BD intercooler also had more cooling tubes than the stock intercooler. Even though they appear to be thinner, they are thicker (width), and there are so many more of them that airflow has very little restriction. |