Big Cams & More!

BIG CAM CUMMINS ENGINES. Many of you know that we at Pittsburgh Power have been working on improvements for the Big Cam Cummins 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 a truck equipped with one of our performance Big Cam Cummins NTC-855 engines, you have been missing out.

Several of our clients pull 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! Another owner operator once told us a story about traveling west on I-80 in Pennsylvania with a heavy, wide, escort load. Driving a rig equipped with one of our high performance NTC 475 twin-turbo engines producing about 800 hp, 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!” One last story about high-performance Big Cams comes from my good friend Dwain Pyeatt, who said that with his high performance Big Cam he was able to run from New Jersey to California and never drop more than half a 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, but many are running them every day doing local work. Some are still running over-the-road, too, 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! Cranked-up mechanical engines will render long engine life when properly driven, but they must be DRIVEN (not just ran on cruise control). For those who may be too young to remember the 1980s and 1990s, a company called King made cruise control pedals for trucks with mechanical engines back then.

If you’re ever going to rebuild one of these great engines, you will have plenty of horsepower and torque available, and will truly enjoy driving with one of these classics under the hood. 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 turbos! Speaking of experience, we have 154 years of Big Cam Cummins experience 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 stop communicating 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, the wires leading to the data port, or in the ECM itself. 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 it, but this has only happened once, so it is not a very common thing.

DYNO TESTING. Many shops will run a truck on a dyno, give you a horsepower and torque reading, and then tell you that your 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 signals. This can be a major problem, because a sensor may be working, but 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 still getting a signal, however it’s the WRONG signal. We find this problem often with turbo boost sensors. The sensor is telling the ECM that the turbo is producing only 25 pounds of boost, but 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 is all the boost available. As an owner operator, you should know how many pounds of turbo boost your engine should be developing at lower altitudes.

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 hp, and 525 to 550 hp at 32 psi of boost. The 15-liter Caterpillar engine produces more horsepower per pound of boost because it has the longest stroke. A longer stroke makes torque and horsepower available at lower RPMs, and requires lower turbo boost. These numbers are for NON variable-geometry turbochargers. I have yet to compile a list of the turbo boost readings for the VG-turbo engines starting in 2008 and newer, but I will put it on my “to do” list!

THROTTLE RESPONSE. The Full Tilt exhaust manifold helps with throttle 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 one (or more) of those three cylinders. You can fix that problem for $1,550 and gain up to half-a-mile per-gallon in fuel savings. Call us today to get yours!

As always, if you have any comments or questions, I can be reached at Pittsburgh Power in Saxonburg, PA at (724) 360-4080. To learn more about all our high-performance products and services that will also make your truck more efficient, visit www.pittsburghpower.com.