Mack Rolls Out Vocational Engines
A recent ride 'n' drive showcased Mack's Internal-Exhaust Gas Recirculation technology that is the solution on its vocational engines for the post-Oct. emissions levels.
In a demonstration featuring dump and trash trucks, Mack invited press and customers to drive unit-pump ETEC engines rated 300, 350 and 460 hp meeting the latest 2.5 g NOx requirement.
Internal EGR is Mack's answer for vocational customers where fuel economy is less of an issue than the simplicity and robustness of the technology. These engines have proven themselves so well, says Mack, that they have been in full production since July, well ahead of the Oct. 1 deadline.
Despite the early introduction, Mack says the development of these engines was not rushed by the acceleration of the EPA deadline. The 15-month pull ahead has simply meant less time at the customer for prove-out. However, with more than 1,000 engines in the field, Mack is confident that the simpler technology of its ASET I-EGR will add, rather than detract, from the strength, reliability and durability of its new engines.
Dual ASETs
The application-specific engine technologies (ASET) from Mack involve a cooled EGR along the lines of competitive engine makers for Mack's over-the-road trucks, where fuel economy concerns are paramount. We reported on Mack's C-EGR early in 2002, and now we are able to give some driving impressions of the I-EGR engines.
First, though, an explanation of the technology itself.
As in all EGR engines, the I-EGR utilizes a proportion of the exhaust re-routed back into the inlet stream to replace some of the oxygen in the air drawn into the combustion chamber. This limits the peak combustion temperature where most of the oxides of nitrogen are formed. Additional fuel-injection controls further enhance the combustion process through rate-shaping of the injection process, adding fuel in a step function to control the first ignition and subsequent burn of the fuel.
Where I-EGR differs from the cooled recirculation is that the exhaust gas is allowed to bleed back into the cylinder from the head and exhaust manifold. An additional bump on the exhaust cam lifts the exhaust valve off the seat as a pulse from an adjacent cylinder arrives to push the exhaust back in to the cylinder. The trick, says Mack, is finding the optimum point for that additional bump, along with lift and duration.
The other half of the trick is the gas-flowing of the head and manifold to get the right proportions throughout the speed cycle of the engine. So the new engines have machined, instead of rough-cast, ports and curved-wall inserts to flow the gases inside the engine.
New pistons with deeper bowls contain the combustion to keep soot off the cylinder walls. This — together with an additional eight quarts of lube oil in the pan and a new filtration system — allow the EGR Macks to live with the same oil change interval as previously: 25,000 miles for on-highway operation/300 hours vocational.
The filtration system includes a bigger filter capacity and a faster spinning CentriMax centrifugal separator, along with Mack's EO-M+ grade oil.
Higher Power
There are some different ratings and different requirements for drivers with the I-EGR engines, says Mack. For starters, all power ratings are at higher rpms than previously with the 350, 400, 427 and 460 Econodynes featuring a flat power peak between 1,600 and 1,950 rpm. The high torque-rise 300, 335 and 370 Maxidynes are at peak power between 1,700 and 1,900 rpm, though are rated out at 2,100 rpm. At their peak these three engines are making 325, 365 and 405 hp respectively.
A special A-rating for use in automatic transmissions is rated 300 hp at 1,950 but peaks at 325 hp at 1,700 rpm.
The AMI-335 and AMI-370 are both new ratings in the Maxidyne lineup.
Mack says that some care must be exercised in selecting axle ratios to suit the new, higher rpms, with the optimal point being 1,700 rpm at the chosen cruise speed with a plus/minus of 50 rpms.
Similarly, drivers are going to have to get used to spinning the engines up just a few extra rpms to enjoy the performance. However, apart from that there should be little difference.
On The Track
We took a variety of dump and trash trucks out onto the Mack test track to see for ourselves. Unfortunately, not being a regular Mack vocational driver, it was tough to pick up any differences from previous ETEC-powered Macks. Suffice to say they pulled the selection of trucks well, both loaded and empty. All restarted using just idle rpms even on the 10% grade and pulled away smartly.
The 460 was a trip, though a little sensitive to throttle in the lower ratios. Either easing down on the throttle — or tromping down on it — eliminated any tendency to surge. Backing up the 460 was Mack's unique T310M triple-countershaft transmission with a low and a low-low ratio. This transmission allows you to shift up through the low range in reverse, swapping gears till you're racing backward at up to 30 mph.
Summary
Externally, there's little to distinguish the I-EGR ASET engine from its predecessor except for the bigger oil pan. And that is the object of the exercise. All the EGR goes on internally with no additional complexity hanging on the outside of the engine. There are cooling system changes that Mack experts will notice, but each is tailored to the specific engine/installation and are all part of the integrated solution Mack is using for its vocational engines.
Cummins Reports Orders For New Engines
Cummins has announced a growing number of orders for its new EPA-compliant engines. The company has increased build rates to fulfill orders from more than 140 fleets.
Several fleets have placed large orders for more than 100 units, including Knight Transportation, P.A.M. Transport, Tyson Foods, Mesilla Valley Transportation and Celadon. This is in addition to many small- and medium-sized fleets that are also placing orders for these new engines, Cummins says.
In addition, Cummins has introduced an Uptime Guarantee program to provide additional confidence for customers trying the new heavy-duty on-highway truck engines.
Allison, OEMs Offer Incentives For Construction Trucks
Lower prices for Allison heavy duty automatic transmissions are temporarily available through five original equipment manufacturers, though only for construction trucks. An Allison HD, formerly priced at about $11,000 over a base manual transmission, now costs about $8,500.
Freightliner, Kenworth, Peterbilt, International and Mack are participating in the HD program, according to Bob Chamberlin, an Allison representative based in California. Deadlines and exact prices differ among the OEMs; Kenworth, for
example, recently extended its program that was to expire at year's end, and now says orders must be received by May 7 and trucks built by June 30.
Only construction chassis for dump, mixer, heavy haul and certain other uses are eligible for a lower priced Allison HD4060, HD4560 and HD4070, Chamberlin said. The General Motors division is currently targeting that vocation, and others may follow later in the year.
He noted that the heavy duty HD, which is rated for engines producing up to 1,550 pounds-feet of torque, now costs about the same as a medium-duty 900-pound-feet Allison MD.
Volvo Offers $2,000 Incentive On VN, VHD
Retail purchasers of new Volvo VNs and VHDs equipped with EPA '02 engines will receive a $2,000 cash incentive for trucks delivered by April 30, 2003.
In addition, Volvo Trucks North America is offering a three-year/300,000-mile extended engine warranty on new VNs and VHDs with EPA '02 engines delivered to the buyer by April 30.
Both the cash incentive and the extended engine protection are limited to customers purchasing from one to five new Volvo trucks from U.S. Volvo Trucks dealers.
Buyers who finance their new Volvo trucks in this program through Volvo Commercial Finance are eligible for additional incentives.
