Call it pre-need planning. When Detroit Diesel rolled out its DD15 engine in October 2007, the company said it was a clean-sheet design, birthed EPA-’07 compliant but also 100-percent ready for EPA-2010. Much of the fuss surrounding the use of SCR may have overshadowed the fact that the engine itself — and the DD13 and DD16 motors too — will not change come 2010.

Engineering tweaks have been performed since the launch, software up­grades, changes in material, component design, etc., but all are part of the natural evolution of any complex machine. Readers may recall my initial impressions of the DD15 back in October ’07 were very favorable, so what I’ve been waiting for is the addition of the oh-ten related hardware. I can say confidently that DD15’s on-road performance hasn’t changed a bit, and may have improved in ways I can’t quantify in a three-hour test drive. I should say, too, that I suffered no ill effects from my brief exposure to diesel exhaust fluid.

All the new stuff, of course, is downstream of the turbocharger — software, controllers, sensors, etc., notwithstanding. If there’s any noticeable difference in the engine, I think it’s even quieter than previous versions I’ve driven.

Walking through the Engineering Test Center garage in Portland, Oregon, techs had a truck hooked up to some monitoring equipment.

I walked within 20 feet of it, and though it was running, all I could hear was a subtle rumble and the clicking of what I presume were the injectors, valves, and other things under the rocker cover. It was amazingly quiet, I tell you, and equally so out on the road at speed.

Aftertreatment System:

For those who never thought an exhaust system had a place in a test drive story… welcome to 2010. The exhaust-aftertreatment system is very much a part of the engine now, and a big consideration for chassis fitters, body builders, and truckers themselves.

DEF tanks come in three sizes
mated to the vehicle’s total fuel capacity

There was much discussion in the early years of SCR development about where they’d hang all that new hardware. It’s been resolved.

Daimler will offer three aftertreatment configurations based on chassis requirements and the intended application.

In addition to the Blue-Tec 1-Box system, a two-box vertical system called 2V2 features separate SCR and DOC/DPF units mounted vertically behind the cab. This configuration lends itself to applications where frame space and ground clearance are larger concerns than a clear back-of-cab area. It permits larger fuel tanks and a right-hand PTO option. It’s available on day cabs in left- and right-hand mounting. The back-of-cab protrusion is said to be similar to the EPA ’07 vertical DPF.

Horizontally speaking, the 2HV system — two-box, horizontal DPF/vertical SCR — was designed for fleets demanding large-capacity fuel tanks on shorter, 220- to 230-in. wheelbase tractors — like many Canadians. It’ll be available on day cabs and sleeper cabs, but not on 58/60- and 70/72-in. models.

Cummins will supply engines with proprietary aftertreatment systems, different from those used on Detroit Diesels.

DEF Tanks:

Also new for 2010 is the DEF tank. They’re mounted on the left-hand side under and just behind the cab. The fill necks are fitted with a 19-mm orifice so you can’t get a diesel pump nozzle in there. There’s also a magnetic lock ring fitted into the filler neck. Commercial DEF dispensing pumps will need to detect this ring before the fluid will flow, preventing DEF from being pumped into a diesel fuel tank.

The tanks have a temperature-controlled coolant-loop heater to keep the DEF warm in winter, and fluid lines running from the tank to the metering unit are electrically heated. A transfer pump is located on the side of the DEF tank, EPA has granted a 70-minute grace period at startup in cold weather, before DEF injection is required. On the coldest days, when the DEF might be frozen, dosing won’t be required until the fluid thaws.

During recent winter testing at ambient temps of minus 20 and 30 degrees F, and even with a cold-soaked, frozen-solid DEF supply, the system was dosing in just 50 minutes (tested using EPA guidelines). Real-world operating conditions will see the fluid heated faster in most cases. 

Detroit D’s DD15 in 2010 dress

In other words, you won’t be sitting idle waiting for the tank to thaw. You can start up, warm up for a few minutes, and then drive away.

Drive Time:

I split my day of driving between three trucks on two laps of the 165-mile loop Daimler uses to test trucks. It’s a combination of four-lane Interstate, two-lane road with mountain grades, and stop-and-go urban traffic. It runs east out of Portland on I-84, around Mt. Hood on Highways 26 and 35, and back into the city from the south.

I got to drive three engines, actually, two DD15s and a DD13. My first drive was the red Cascadia — a customer-spec’d demo unit awaiting delivery. Its DD15 was mated to a 9-speed manual transmission, attached to a rather tall set of rear ends. It clearly wasn’t set up for this terrain. It cruised 1,150 rpm at 55 mph — 150 rpm above peak torque — which is rather low for the DD15’s sweet spot. It did better at 65 mph, but Oregon has a 55-mph speed limit.

On the first loop, I ran alongside a day cab equipped with a DD13 and a 10-speed, which actually out-pulled the gear-bound DD15 I was driving on the uphill side of the loop — though not through any fault of the bigger engine. I couldn’t keep the engine within the proper torque range for the pull (1,100 to 1,200 rpm) at an appropriate road speed because the gear steps of the 9-speed were so vast. Dropping a gear put the engine speed too high, or the road speed too low. It’s a flatlander, that truck.

I switched to the day cab half-way around the loop, on the downhill side, and have to say the difference in driveability was stunning. The closer steps of the 10-speed and the more reasonable 3.70 gears made all the difference. Later in the day, I made the entire loop in a third truck, equipped with a DD15, a 10-speed UltraShift, and even taller gears than the first one… 2.64:1. A direct-drive transmission and low-pro wide-base single drive tires made the difference. It worked like a charm, too.

The second DD15 and the DD13 both did a remarkable job in the hills, and pulled like champs in their peak torque ranges. Likewise on the downside, the engine brake was so strong at higher rpm that it was slowing the truck down on the grade. Switching the Jake to position 2 was the solution.

The DD13 boasts all the same features as its bigger brother (it’s essentially the same engine, just a smaller package), including the broad, flat torque curve. You actually gain about 150 lb ft of torque as the revs fall from 1,400 to 1,100 rpm, meaning it pulls harder as the revs drop. Throttle and turbo response are like no other North American engine — in my opinion — and will please performance-demanding drivers immensely.

So, what about the SCR implications? There weren’t any. The system is totally transparent to the driver, there’s no need to manually intervene at any time, no switches to flip or gauges to watch — save for the tank level. So, 2010 is something of a non-event in that regard. 

Seven years ago Detroit Diesel’s heavy-duty engine platform was just a twinkle in some engineer’s eye. The company has invested close to $2 billion turning that twinkle into the DD13, 15, and 16.

They’re remarkable machines offering good fuel economy and terrific performance, and they’re among the cleanest engines on the planet right now. The recently announced nine-grand upcharge sounds like a lot until you consider what you get for your money. Namely, lots.