The Big Cam Cummins: Many of you know that Pittsburgh Power has been working with this great engine for 40 years. We have designed parts, systems, timing codes, horsepower settings, piston coatings, and the list continues. In fact, one day while sitting at my desk, I counted 42 items we brought to market for the Big Cam, then I stopped counting. If you never had the pleasure of driving one of our performance Big Cam Cummins NTC-855, you missed out on quite a driving experience. Several of our clients pulled heavy equipment and one of them told me he would judge how much torque he was using by how far the hood would separate from the cowling of his A-model Kenworth.
Here’s another story: An owner-operator was traveling west on I-80 in Pennsylvania with a heavy, wide, escort load with one of our high performance NTC 475 twin-turbo Cummins producing about 800 horsepower. He was on Snowshoe Mountain and pulled away from his rear escort when he called her on the CB radio asking why she wasn’t behind him. Her answer was “I can’t keep up, I have the Coupe De Ville Caddy to the floor!”
Last story about high-performance Big Cams: My good friend Dwain Pyeatt built one and was able to run from New Jersey to California, never dropping more than ½ gear with a 13-speed in a 359 Pete at 80,000 pounds.
Now, why are we talking about an antique engine, you may ask? Because many people are re-doing older trucks, some as toy trucks, however, many are running every day doing local work. Some are still running over-the-road along with the 425-B and C mechanical Caterpillar engines. That’s another great engine, and one that will also produce great power when properly set up and driven correctly! Mechanical engines cranked-up will render long engine life when properly driven, and they must be DRIVEN, not just setting of the cruise controls and letting them go. Yes, King Cruise Controls did make them for mechanical engines. I just wanted to let the younger owner-operators ho were not around back in the 1980s and early 1990s know that we still had great-running trucks! If you’re ever going to rebuild one of these classics, you can stay with the mechanical engine, have a lot of horsepower & torque, and enjoy driving the classic!
Pittsburgh Power stocks just about every Big Cam Cummins part needed to build a great engine! We stock more of these parts than anyone in North America! In fact, we still build the fuel pumps and injectors in our fuel injection shop. Pat Sharp, our pump and injector rebuilder, has been with us for 34 years building these components along with turbochargers. Yes, we still rebuild those older turbochargers. Speaking of experience, we have 154 years of Big Cam Cummins between Pete, Pat, Shawn, Brian, and myself.
Qualcomm units: Many companies require trucks leased onto them to be equipped with a Qualcomm. However, as the trucks age, wiring issues become a problem and the Qualcomm will not communicate with the ECM on the engine. We have been doing a lot of work in our electrical engineering department diagnosing these problems. Many times, the problem is in the data port, wires leading to the data port, or in the ECM. Furthermore, they must be turned on in order to transmit information to the Qualcomm. If you are installing a Qualcomm in your truck and are having issues, just bring the truck to our shop and we’ll make it work for you. Sometimes the ECM is at fault and the only option is to replace the unit. This has only happened once where we had to install a new ECM.
Dyno testing the Pittsburgh Power Way: Many shops will run a truck on a dyno and give you a horsepower and torque reading and tell you the truck is okay. However, as you drive it, you KNOW it’s sluggish and feels like it’s low on power and response. Our engineering team has developed ways to test response, acceleration, horsepower, and torque, along with the sensors to make sure the ECM is getting the correct signal. This can be a major problem: A sensor may be working however the signal going to the ECM is incorrect. Sensors can fail in their operating range and the ECM doesn’t recognize it because it IS getting a signal, however it’s the WRONG signal! We find that this has a lot to do with turbo boost sensors. The sensor is telling the ECM that the turbo is producing only 25 pounds of boost, and when at wide-open throttle, it should be 30 psi of boost. So now, the 500 horsepower engine will only develop 416 horsepower because the ECM thinks that that is all of the boost available. As an owner-operator, you should know how many pounds of turbo boost your engine should develop at lower altitudes. Many people think they have a 500 hp engine when only 416 hp is being developed. There are many other sensors on the engine that can also produce faulty signals. However, the dyno operator must be able to recognize this problem! In general, a diesel engine of 12 to 15 liters will produce 28 psi of boost at 460 hp, 30 psi at 500, and 525 to 550 hp at 32 psi of boost. The Caterpillar engine, 15 liter, produces more horsepower per pound of boost because it has the longest stroke. Stroke makes torque and horsepower at lower RPMs and requires lower turbo boost. These numbers are for NON variable-geometry turbochargers. I will have to compile a list of the turbo boost readings for the VG-turbo engines starting in 2008 and newer.
The Full Tilt exhaust manifold also helps with response because of the elimination of turbulence and the fact that it flows 20% more exhaust. Another advantage of this manifold is a reduction of exhaust gas temperature by 125 degrees. With the added exhaust flow, the turbo makes boost quicker and the turbo boost sensor records this and sends the signal to the ECM, allowing the fuel to be delivered sooner by the injectors to the pistons for throttle response. The Full Tilt intake manifold for the ISX Cummins also helps to deliver more boost sooner to the pistons and distributes the compressed air much more evenly to the air-starved cylinders, which are #1, #2, and #6. If you pay attention to ISXs that have failed, it’s usually those 3 cylinders. You can fix that problem for $1,550 and gain up to ½-mile per gallon in fuel savings.
Written by: Bruce Mallinson, Pittsburgh Power, Inc., 3600 S. Noah Dr., Saxonburg, PA 16056 Website: www.pittsburghpower.com Phone: 724-360-4080