If all the new emissions-friendlier power units perform as well as Mack’s new C-EGR engines, that should go a long way in silencing the fears of drivers who are wary of what they consider to be untested products.
Judging from the 350 tough miles this editor experienced driving the new exhaust gas recirculation engine, the over-the-road driver is in for a treat. The drive along Interstate 80 from Allentown, Pa., to Nescopeck, Pa., included pulling plenty of hills grossing 78,000 pounds. Neal Biser, Mack’s 29-year veteran lab technician, and I ran north on U.S. 33 out of Allentown to I-80 and headed west, a drive that would test any truck’s pulling power and overall performance.
The Environmental Protection Agency’s new regulations put engine manufacturers under the gun to meet stricter emissions guidelines by Oct. 1. Mack, like nearly all of the other engine markers, has been honing exhaust gas recirculation technology in an effort to meet the requirements. The notable exception is Caterpillar, which will miss the deadline as it pursues a different technology. EGR captures some exhaust and uses it to displace some of the normal air intake. This retards the formation of NOx (nitrogen oxides), which forms smog when combined with sunlight and hydrocarbons.
Mack’s CH 427 horsepower engine has plenty of torque throughout the power band, and throttle response is excellent. Biser noted the variable geometry turbocharger picks up more quickly than turbos in pre-EGR engines. “You will start to feel turbo response within 200-300 rpms rather than 400 or 500,” he said.
Mack has been developing its ASET technology using EGR for five years and has done considerable real-world testing. According to Steve Homcha, executive vice president of Mack’s Class 8 program, “Being an integrated manufacturer of both trucks and engines has given us a tremendous advantage in providing all customers with optimum solution to EPA ’02.”
Mack has introduced two EGR systems, one for its vocational products, I-EGR, and the other, C-EGR, for its over-the-road tractors. Mack uses the cooled EGR for its on-highway trucks because it is more efficient in a steady state environment, where speed, load and other operational factors are relatively constant, according to Steve Ginter, marketing vocational product manager at Mack. Internal EGR is used for vocational products, where stop-and-go driving is the norm.
The Mack ASET C-EGR engine uses exhaust gas recirculation technology to meet the stricter emissions requirements.
The variable geometry turbo, while responding quicker, can fool a driver not used to its unusually quiet operation. There is none of the typical turbo air-sucking, rush sound to make a driver think he’s going fast. Instead, there is a high-pitched whistle of significantly fewer decibels that spools up and down as the engine’s computer feeds it data. The electronic control module senses fuel needs, air intake, and a myriad of other factors along with the engine’s new requirements to recirculate highly specific amounts of hot exhaust. Biser, who works on noise, vibration and irritability factors at Mack’s vehicle development lab, said Mack has done considerable work in creating a quieter, sturdier driving environment.
The spooling sound sometimes seems unconnected to the driver’s throttle use because the turbo is responding to many different commands. But behind the whistle when I depressed the throttle, a faint rush of air could be heard, the only indication the turbo was gulping air in response to driver and engine demand.
A more noticeable feature of the variable turbo is that it tends to pull rpms down a little faster between shifts, Biser noted. My experience bore that out. The Fuller 10-speed shifted smoothly and easily. Despite the quieter turbo and engine sound, drivers who shift by ear will have no trouble coordinating their driving skills with this new technology.
Even the fan sounds different. It is very quiet and comes on only to the degree it is needed, explained Biser. Besides being quieter, the fan’s response keeps water temperature at a more constant level. According to the gauge, the water temp rose no more than one might expect, and oil temperature remained at 208 degrees in steady state throughout the trip.
Cab comfort was quite good on a day during which we used both the heater and the air conditioning. It might seem that increased under-hood temperature would heat up the cab, but I did not sense that at all.