10-4 Magazine - For Today's Trucker

June 2005 - Performance Zone

BACK TO THE BASICS?
By Performance Specialist Bruce C. Mallinson

Sometimes in life we have to go back to the basics. Think about the new Class 8 truck engines we have to live with today. Are they better than what we had 10 years ago? According to the reports I’m receiving on fuel mileage, response and power, I don’t think so. Read on and then make your own decision.

Let’s start out by talking about the engines of 1995 through 1997 - like the 550 Cats, N-14 Cummins and the DD3 Detroits. Fuel mileage was always around 5.7 mpg and higher, and many owner-operators could obtain up to 7.2 mpg. If you were unhappy with your engine’s performance, you could install the Pittsburgh Power Performance Computer and you had all the power you ever dreamed of and improved fuel mileage as well. Engine life was great - many times these engines ran over 1.2 million miles before a major overhaul needed to be done. We never had power problems with the 5EK, 6TS, 1LW, and 5DS Cats, the 1844 and 2025 CPL N-14 Cummins, and the DD3 Detroits.

The DD4 only needed a turbo change to improve the fuel mileage to make them as good as the DD3.
But now, what do we have today? The ISX EGR Cummins is the leader (in fuel mileage), averaging 5.4 to 5.5 mpg. The Acert Cats are averaging 4.7 to 4.8 mpg and the EGR Detroits, along with the EGR Macks, are lower than the Cats. These numbers are pitiful! Think about this: there are 16.1 million semi trucks on the highway every day. If the fuel mileage is down with the new engines by just 1/2 of a mile per gallon (from 5.5 mpg down to 5 mpg) and the average truck runs 100,000 miles per year, each truck will consume an additional 1,819 gallons of fuel every year. At $2.20 per gallon (which can be hard to find right now), the additional cost per truck per year is just over $4000. I think that four grand would be better in your pocket than in burned (wasted) fuel sent up into the atmosphere.

Those of you who know me know that I truly believe that a truck with high horsepower that is properly geared and setup with a free-flowing exhaust and FASS System to remove the air from the fuel, driven correctly, will obtain great fuel mileage. On the level highways, keep your turbo boost between 10 and 12 psi. If you have the power, you can run 75 plus mph into the wind with your engine using 25 psi of turbo boost, however the fuel mileage will be LOW for that trip. Use that 18-speed transmission and drop 1/2 a gear. Bring the turbo boost down to as close as you can get it to 10 psi. Choose an rpm that will allow the engine to pull effortlessly and the fuel mileage will improve. How you drive is a major factor in regards to mileage and engine longevity. Here are a few driving tips to consider that might help.

Use your horsepower on the rolling hills and on the mountains to keep up your momentum. Rolling hills (such as I-80 in Western Iowa) require a lot of power to try to maintain a given speed, such as when the cruise control is on. Turn off the cruise control and drive the truck like we did back in the 1980’s. Accelerate the truck prior to getting to the bottom of the grade. Get the turbo boost up to what you think it will take to pull the next grade as you hit the bottom of the hill. Hold the throttle at that position, maintaining your predetermined turbo boost, and when you get near the top of the hill, ease out of the throttle. The boost should drop to around 10 psi or less. Coast down the next hill (or you may need a little throttle) and, again, accelerate prior to the bottom of the hill. Your turbo will live longer, the truck will run easier, and your fuel mileage will improve. Your speed will only vary by about 5 mph and you’ll be driving the truck instead of just holding onto the steering wheel. Do your truck a favor and save the cruise control for the level terrain.

Did you ever wonder why some drivers go through so many turbochargers? Do you think the rapid rate of acceleration of the turbo could possibly have anything to do with spinning the turbine wheel off of the shaft? A turbo spins at 8,000 rpm at idle and 110,000 rpm or more pulling a hill at wide-open throttle. So when either your right foot or the cruise control pulls hard on the throttle, it’s putting excessive strain on the turbine wheel. It’s the heaviest piece in the turbocharger and its only friction welded to the shaft that is connected to the compressor wheel which draws the air through the air cleaners. Running your truck smooth will extend the life of your turbocharger.
What about air pollution and waste? If each truck on the highway drops 1/2 a mpg because of the new engines and uses an additional 1,819 gallons of fuel every year, then the 16.1 million trucks on the road will burn an additional 29,285,900,000 gallons of fuel per year. At $2.20 per gallon, the trucking industry will spend an additional $64,428,980,000 on diesel fuel. And that is with only a 1/2 mpg drop - some of the new engines are losing as much as 1 mpg than the engines from the mid 1990’s.

We meet owner-operators every day that are still running 425B mechanical Cats and BC3 Cummins (with the horsepower turned up) that are getting 5.7 to 6.2 mpg. Not bad for 1980’s technology. So should we be going back to the basics? With less gallons of fuel burned into the atmosphere and more money in your pocket, I think that question answers itself.