High Performance Diesels

The summer heat is upon us and the same problems keep surfacing with the low-flow cooling on the 1986 through 1991 NTC Cummins engines.

Roger from Phoenix, AZ, wrote to us about his low-flow cooling 1990 NTC 444XT CPL 1280. "My engine runs great," he says. "I've installed your ceramic-coated pistons, mapwidth enhanced turbo, dual fuel line kit, high volume fuel pump, high-flow injectors and premium gold heads. On the dyno I've got 618 horsepower to the ground and Cummins says that's 772 flywheel horsepower. I love my old Pete and the 444 engine. How can I keep it cool?"

The low-flow cooling system can be a problem. Gary Hoffman, president of Diesel Injection has been working with this problem for 10 years. He highly recommends that you revert the low-flow system back to the high-flow system used on all small cam and Big Cam I, II, and III engines. Regardless of the horsepower output of the engine, the high-flow system that Cummins used through 1985 worked superbly. We never experienced high water temperature so long as the radiator, water pump, and radiator cap were functioning properly.

The expensive part of this conversion is the radiator. Gary highly recommends a new BCIII style radiator. However, some of the low-flow radiators can be used by removing the baffle in the tank. You will have to install a top inlet hose fitting and a bottom hose outlet fitting when using your existing radiator.

If you ever thought of installing an air-to-air intercooler on your engine, now is the time to do so. There must be at least three inches of clearance between the radiator and the grill. The 425 hp Caterpillar radiator is built to accommodate the air-to-air cooler. So, now all you have to do is order a 425 Cat radiator, and install our CTC intercooler along with the high-flow conversion kit and you are set for some heavy-duty trucking with low exhaust and water temperatures.

Please don't forget to remove the restrictions under the water manifold.

Gary has compiled a list of the parts necessary to convert the low-flow to high-flow. They are as follows:

Converting low flow to high flow

  • the thermostat housing
  • seals
  • bolts
  • gaskets
  • new thermostat housing to water pump transfer tube
  • tab for the water tube
  • water transfer tube to the oil cooler
  • water pump bolts
  • water filter
  • water filter head
  • water filter head bracket
  • water filter shut off valves
  • idler pulley and adjustment bolt
  • water pump belt

Diesel injection has the complete kit available.

My booklet is now available at http://www.dieselinjection.net. Our e-mail addresses arebruce@dieselinjection.netpete@dieselinjection.net, and gary@dieselinjection.net. If you would like our booklet on high performance Cummins diesels give Aimee a call at 724-274-4080. There is a $9.00 charge for shipping and handling. Just call us with your MasterCard, Visa, AMEX or Discover card number. Our address is Diesel Injection of Pittsburgh, Inc., 1403 Freeport Rd., Cheswick, PA, 15024.

The above column is the opinion of the writer and d