Cummins Unveils '07s
Steve Sturgess
Executive Editor
Cummins unveiled its ISM and ISX big-bore engines last month, reminding the press corps that it's keeping its promise: The engines in 2007 will be basically unchanged from the '02 EGR engines.
The company said its engines for the new emissions regulation in '07 will have few changes, other than a diesel particulate filter (DPF). See related story on page 100.
Down the scale, though, ISB gets a capacity boost to 6.7 liters from 5.9 and the ISC and ISL now feature cooled EGR for the first time.
In a press conference just before the Technology and Maintenance Council spring meeting in Tampa, Cummins President Ed Pence said the Cummins on-highway line-up is made up of the five above-mentioned engines and that, far from exiting the truck engine business, Cummins is ready for 2007. Reports to the contrary had been widespread following remarks by company chairman Tim Solso.
In fact, Pence said, Cummins has pulled back from the low point several years ago and has aggressively gained market share from 21 percent to 26 percent today. In addition, production has skyrocketed from 135 engines a day to 430-plus daily. Most importantly, through cost efforts, the break-even point is at a 50 percent lower volume. That provides a major cushion should the market go south following introduction of the 2007 engines.
Describing the 2007 technologies, Steve Charlton, executive director heavy-duty engineering, introduced the subtle changes to the air handling on the ISX. These include a revised Holset variable geometry turbo (VGT) that is now electronically controlled with steeper motor actuation instead of the previous air control. The exhaust cooler has been redesigned, fitting a more efficient package to handle the higher rates of recirculation into the same location on the engine. At the same time, Cummins has relocated the EGR valve from the hot side of the engine to the cold side where it is in a much more favorable environment. And there's a new, more elegant crossover tube at the rear of the engine.
On the fuel side, injection pressure is up again from an injection camshaft change. Another added component is the closed crankcase breather that mounts on top of the cam cover. This is a passive coalescer with a filter element that has to be changed out at every fourth oil change.
Allaying fears about DPF maintenance, Charlton said that, according to application, the much feared cleaning cycle would be anything from 250,000 miles and up to 400,000, and that would mean for many operations it would be two years and more into ownership of the truck before DPF removal and cleaning would be necessary. And the cleaning process is simplified with a filter processor Cummins has developed (see separate story).
The DPF displayed was configured for vertical installation and was only a little larger than a conventional muffler. It has an oxycatalyst stage ahead of the monolithic particulate filter with temperature sensors at the inlet, mid-chamber and at the outlet and pressure sensors measure the pressure drop across the filter stage.
The oxycat oxidizes nitrous oxide in the engine-out exhaust to nitrogen dioxide which – if the filter matrix is at a high enough temperature – will react with the carbon to produce carbon dioxide and nitrous oxide, purging the particulate matter from the filter. This continuous purging of the carbon is passive regeneration and in many applications goes on in normal truck operation. For extreme cold or in applications where the exhaust cannot be brought to temperature, active regeneration sees a very small dose of fuel injected into the exhaust stream to heat the matrix to promote the chemical reaction that removes the carbon.
The need for cleaning comes from the ash byproducts of the lube oil additives. The actual amount of ash is very small – hence the long maintenance period – but the ash does collect and does need to be emptied.
The passive regeneration is maximized using the new, more powerful engine electronic controls. More power and speed from the ECU are necessary, because the electronics have to control the VGT, the EGR valve, fuel and the DPF. However, according to Charlton, this additional computing power, plus the electronic controls for the VGT make the '07 ISX even sweeter to drive that the '02. He said the difference is as great as the step between '99 and '02 engines and drivers in the test fleets were clamoring to drive the beta-test engines.
According to Charlton, in redesigning parts of the air handling system, Cummins has been able to target areas that may have caused problems and that engine reliability would be one of the benefits of the model change. Fuel efficiency would not be compromised, he said, and they anticipate no degradation of fuel economy from today's engines.
Jeff Weikert, Cummins executive director of medium-duty engineering introduced the medium and light-heavy ISB, ISC and ISL. The ISB, which already is an EGR engine, gets a boost in displacement to 6.7 liters (which will likely please '07 Dodge diesel pickup buyers) and a new top rating of 325 horsepower and 750 pounds-feet. Other changes include the Holset VGT across all power ratings for the B and engine ECU common with the ISC and ISL.
The latter engines, which have been running on credits since '02, will have cooled EGR in '07, along with the Holset turbo.
Because these engines are common-rail fueled, the engineers have developed an elegant way of initiating the active regeneration. The multiple-event injection gets a final squirt of fuel after the exhaust valve opens and in the blow-down stroke fuel is pushed out into the exhaust stream. In contrast, on the ISX, a water-cooled injector sits on the outlet from the turbo.
All engines feature the Fleetguard crankcase ventilation filter and have the same maintenance requirement.
Little was mentioned about the ISM, though it is still very much in the program. Like all these engines, it will have the VGT and the DPF. It will also share the more powerful ECU with the ISX and feature the same Fleetguard crankcase filter.
On fuel economy and lifetime costs, Jeff Jones, vice president of sales and market communications, said that most engines would be at today's fuel economy levels. Gains made in small refinements would offset the lower density of the low-sulfur diesel fuel. And on maintenance cost, he said that since the additional crankcase filter and the DPF would likely be at today's lube oil change intervals – which themselves would not change – there would be only a small incremental cost over the life of a vehicle. He said the service channel is ready, with 1,000 dealers currently in training and would be fully equipped to service the 2007 engines when they start to appear.
Equipment continued...
