Cummins Cooling Mods

Keeping EGT and Coolant Temps in Check in A Modified 6.7L Cummins

With 800 lb-ft of torque or more on tap and a stack of massive heat exchangers onboard, it’s no wonder modern diesels perform so well straight from the dealership. But what happens after we’ve doubled the factory horsepower rating? Are we still safe to tow the same 12-to-15 tons we did when the truck was bone stock? Believe it or not, the answer is both yes and no. While the factory intercooler can suffice, with hundreds more ponies in the mix, it usually means we’re watching gauges more than we’re watching the road or that we’re forced to hold back the horsepower reins while climbing grades.

Upon adding a PowerFlo lift pump and S467.7 (by way of a second-gen turbo swap kit) from Fleece Performance Engineering, the ’12 Ram 2500 shown here was making a dyno-proven 570 hp and 1,140 lb-ft at the wheels. However, even with the stock injectors and CP3 still in the mix, the owner was seeing EGT crest 1,500 degrees on prolonged pulls. To cool the 6.7L Cummins off, he reached out to the cooling experts at Mishimoto for a full intercooler kit. Then, for added peace of mind when working the truck hard, one of Mishimoto’s performance radiators was bolted in place of the stocker.

During our half-day install, the direct drop-in radiator fell into place within minutes, while a few massaging measures were required in order to accommodate the massive, 100-percent thicker Mishimoto intercooler. With a 190-degree drop in EGT and lower coolant temps when all was said and done, we think the results speak for themselves.

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