Emissions: Detroit’s direction
With the 10/02 emissions deadline approaching, a vast amount of misinformation regarding the future of heavy-duty diesel engines still exists. This is the third installment in a series giving manufacturers a chance to explain their solution, in their own words…
Before we talk specifically about the new standards, it is worth spending a moment to review the progress the heavy-duty engine industry has made over the years. The chart to the right, at the top of the page shows where the standards were in 1970, and the steady reduction in emissions over the years. The October 2002 standards are identified under the arrow labeled “pull ahead.” The chart tells an interesting story. Those who have been in trucking since the 1970s will remember that the typical fuel economy in that period, for a heavy-duty truck, was in the three to four mpg range. Over the years, as emissions have been reduced, fuel economy has improved significantly. Interestingly, almost every time a new standard has faced the industry, there have been concerns about the possible impact on fuel economy. But, the industry has always found ways to improve engines so they meet new standards and provide ever better fuel economy, performance, and durability. It is also worth noting that the chart shows the level of emissions produced by future diesel engines will approach zero.
Since 1992, truckers have made the Detroit Diesel Series 60 engine the number one heavy-duty engine in North America. Truckers buy more Series 60s than any other heavy-duty diesel because it gives them the best combination of performance, fuel economy, low cost of operation, reliability, long life to overhaul, low frequency of maintenance intervals, high driver satisfaction, ease of service, overall warranty satisfaction, electronic features, and residual value.
There are several reasons why the Series 60 is so popular. It was the first engine designed exclusively with electronic controls, which have now evolved into the highly advanced DDEC IV system.
The engine also features individual unit injectors, multiple piece pistons, and an overhead camshaft. The overhead cam eliminates push rods, which allows for significantly higher injection pressures. Without the need for “space-claim” for pushrods passing from the block to the head, the head bolt pattern and intake and exhaust port shapes and sizes can be optimized. The end result is a lot of flexibility in controlling the combustion events in the engine. As other engine manufacturers have introduced new products in the last few years, they too have migrated to the basic design concepts found in today’s Series 60. The bottom line is that the Series 60 provides the best design on which to apply newer technologies to reduce emissions and maintain good fuel economy.
In addition to the Series 60, Detroit Diesel also manufactures other high performance engines, with dual overhead cams, sequential turbochargers, and common rail fuel systems.
Detroit Diesel has also placed more than 2,500 EGR equipped engines into service since the year 2000.
When the EPA announced the new emissions standards, Detroit Diesel examined all of the technology that existed throughout the industry and began testing different versions of the Series 60. Detroit Diesel also has the benefit of being part of DaimlerChrysler and has had access to all of the worldwide diesel technology available from Mercedes Benz. After analyzing the various approaches available, Detroit Diesel decided the best approach for October 2002 is to apply proven EGR technology to the proven and popular Series 60.
Alternate approaches are likely to involve retarded timing that typically leads to poor fuel economy, reduced performance, and increased soot in the oil. Using advanced EGR, controlled by DDEC IV, reduces the need for retarded injection timing.
When testing of the first Series 60’s with EGR began several years ago, four goals were established, in the following order: meet the new emissions standards, improve performance, maintain or increase durability, and maintain or increase fuel economy. As this article is written, the first three goals have been reached, and now the focus is on further improving fuel economy.
Where is fuel economy now? On average, it is within a couple of per cent of the current engine, with the range being approximately .5 per cent to 3.5 per cent lower, depending on the rating. But this situation is no different than Detroit and the other engine makers have faced over the years. Tougher emissions standards are introduced, and the industry works hard to meet the standard, and improve fuel economy at the same time. History shows that both are possible.
The goal at Detroit Diesel is to have the 2002 engine at the same level of fuel economy as the current engine, when it is introduced in October. As is our customary practice, DDC will certify the Series 60 engine approximately 60-90 days prior to Oct. 1. In the meantime, work continues.
There are already a number of 2002 Series 60 powered trucks in the hands of customers in revenue service, as well as test trucks running cross country, and dozens of engines in test cells. Not to mention the 2,500 EGR-equipped engines running across North America since the year 2000. The following DDEC Report, printed on May 8, 2002, from a truck in service with a truckload carrier, is of interest. The engine is a 2002 Series 60 with EGR. After 33,095 miles, with a maximum speed of 72 mph and an overall average speed of 55.6 mph, driving fuel economy is 6.91 mpg. Experienced truckers will know that fuel economy tends to increase in the summer months and as the truck and engine break-in. So, 6.91 mpg for a new, fully loaded truck, in the winter months, running an average speed of 55.6mph is very good, some might say excellent. Detroit Diesel feels confident in the ability of the 2002 Series 60 to maintain its leadership role, particularly in the area of fuel economy.
There were some early concerns about an increase in the amount of maintenance the 2002 engines would require. Experience has shown that by using EGR and advanced timing, the soot loading issue in the lube oil never materialized.
Truckers who switch to the new CI-4 oils can maintain their current oil change intervals.
– Special to Truck News, this story was prepared by Detroit Diesel Engine Corp.
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