It’s a heck of a time to be making heavy-duty diesel engines. Fuel prices are skyrocketing, emissions regulators are raising the bar yet again on exhaust, and customers just keep lining up to buy more iron.

Make that big iron. When Caterpillar, Cummins Engine, and Detroit Diesel all introduced new ratings or refinements to their engine lines, the common trend was a move toward the high side. Caterpillar unveiled its C-15 and C-16 engines last month at the Great American Trucking Show in Dallas, showcasing a quieter, lighter-weight, smarter, and more powerful edition of its meaty 3406E (our road test begins on page 68).

A few weeks earlier, Cummins took the wraps off new ratings for its 15-litre ISX line. And Detroit Diesel announced a 550-horsepower Series 60 rating and new maintenance option for its electronic engine controls.

CATERPILLAR

It’s true that Cat’s C-15 and C-16 engines borrow a lot from the 3406E. The C-15 has the swept volume of the familiar 14.6-litre 3406E, while the C-16 is the bored and stroked 15.8-litre introduced two years ago as the 600-hp 3406E. But the biggest difference is what’s left behind: the slimmer block and internal iron changes mean the new engines are almost 200 pounds lighter than the earlier E-model engine. The biggest contributors to the lighter weight are a more efficient block design and a lighter crankshaft, flywheel, bearing caps, and air compressor.

The extra rigidity in the block, plus changes to the camshaft cover on the front of the engine and a flexible-mounted, de-coupled oil pan, mean the new engines are quieter, even with the elimination of the sound cladding.

There’s less material in the block walls, as evidenced by the spacers that now have to be used to position the fuel filter and the engine electronic control module in their conventional positions to ease the repackaging of the engines into existing 3406E applications.

Other detail iron changes address reliability, with enhanced seal technology in the cam access cover, the flywheel housing, oil pan, water lines, and the front-plate-to-block joint.

The latest ADEM 2000 electronics allow for rate-shaping of the injection process, that reduces NOx emissions without loss of fuel economy. In fact, adoption of ADEM 2000 means the new engines offer slight economy gains over the earlier 3406E models, despite the stricter emissions requirements for 1999.

Ratings for the C-16 include the 600 with 2050 pounds feet and a 575 hp rating with 1850-peak torque. The C-15 comes in a wide variety of ratings from 355 to 550 hp and peak torque to 1850 pound feet.

Our four-day road test of a prototype C-16 engine provided insight about how these refinements translate to the road. The story begins on page 68.

CUMMINS ENGINE CO.

Cummins has added two new ratings to its 15-litre ISX engine line and is set to roll into full production this month on the complete range. The new motors are a 475 and a 475 ST2 “Smart Torque” version. The straight 475 develops 1650 pound feet of torque at 1200 rpm, while the ST2 does the same and then adds another 200 pound feet in the upper two gears. Cummins says fuel economy should be the same with either engine.

Built on the same platform as the premium Signature 600 launched in 1997, the two 475s-like all ISX models-also have a killer engine brake built in. In this case the Intebrake, designed by Cummins and then refined by Jacobs, builds as much as 500 retarding horsepower. The company also says, incidentally, that a six-position retarder switch will be standard fare on ISX and Signature engines.

The rest of the double-overhead-camshaft ISX range offers ratings from 400 to 600 horsepower. You’ll be interested to know that Australia gets a Signature rated at 650 horsepower and 2250 pound feet-in that case mated to Mack’s beefy triple-countershaft transmission, the only one so far that can handle all that torque. Cummins says it could go higher if there were drivetrain components strong enough to take the stress.

ISX engines fall into three families, starting with the 400- and 450-hp X-I family rated at 1800 rpm for economy-minded fleets.

Next are the 475- and 500-hp X-II engines rated at 2000. The ISX 565 and 600 comprise the X-III family, with 1850 pound feet for users who want performance without spending a bundle on up-front drivetrain costs. These are hardware families offering easy uprates to the highest horsepower in each group to enhance residual value at the time a truck is traded.

Family III and I engines are already in production, and Family II was to start Oct. 1, at the very modern ISX/Signature plant in Columbus, Ind. The plant has been specially laid out to encourage truckers to visit (in fact, they get the best parking -there are several tractor-trailer spots right up front).

Cummins is eager to please Signature and ISX owners and especially eager to keep them rolling. With service help on call 24 hours a day, seven days a week, the company will ship both parts and a technician to a problem site if need be. “Whatever it takes,” says Tom Kieffer, executive director, marketing. If you’re down over lunchtime at a Cummins shop, the company expects the distributor to take you out to eat. If you have to be there overnight, they’ll arrange a hotel room. Longer, you’ll get a rental truck.

The distributor has total discretion in how he works to make you comfortable or get you back on the road. Like Kieffer says, whatever it takes.

DETROIT DIESEL

In an exclusive arrangement with Freightliner, Detroit Diesel will offer its Series 60 engine at 1850 pound feet and 550 horsepower. The rating is designed to produce at least 450 hp from 1250 rpm upward.

The engine is managed by Detroit’s very capable electronic control system, DDEC IV, which has also received some enhancements. During the Great American Trucking Show, the company demonstrated its new Maintenance Alert System (MAS) for all DDEC-controlled engines. MAS is a completely automatic DDEC option that monitors engine fluid levels and looks for air and fuel restrictions. Sensors check the oil level, coolant level, and pressure drops across the fuel and air filters and provide input to the MAS cab-mounted display. The display gives a visual signal which easily identifies the fluids and filters that are at acceptable levels, marginal levels, or need attention. MAS eliminates downtime and stretches service intervals.

In theory, MAS means you’ll never have to physically guess at the oil level again-the system will tell you when you need to top up, as well as how much oil to add. Ditto for coolant and fuel filters,

THE REST OF THE PACK

Cat, Cummins, and Detroit aren’t the only engine makers making news lately. Earlier this year, Mack Trucks announced an addition to its E-Tech 12-litre diesel engine lineup-the E7-460XT. Based on Mack’s E7-460 E-Tech, the E7-460XT produces peak torque of 1760 pound feet at 1200 rpm. It reaches a maximum of 490 horsepower between 1600 and 1700 rpm, has an operating range up to 1850 rpm, and torque rise rated at 30%.

The E7-460XT will initially be available in Mack’s CH and CL models and only with Mack transmissions.

All E-Tech engines are covered by a three-year/30,000-mile/10,800-hour protection plan and a five-year/500,000-mile extended warranty.

Volvo Trucks last month started to deliver its 12-litre VE D12C diesel, a 465-hp engine with 1650 pound feet of torque. Early in 2000, it will be joined by 345-, 385-, and 425- hp versions.

Besides better torque output, the engines feature new-generation electronics, and enhanced communications over the SAE J1939 datalink allow the anti-lock braking system, airbags, transmission, instrumentation, and other components to exchange information more readily.

Changes to hardware include reinforced cylinder block to accommodate new timing gears; stiffer bottom end for better bearing support; enlarged oil cooler; single-piece laminated oil pan for reduced noise; single fuel-line return for reduce leakage potential; and a redesigned front geartrain.