I’m a big-truck guy at heart. Big sleepers, big motors, big loads; but I have to say, the little MBE 900 engine under the hood of this day-cab Freightliner M2 got me thinking. The truck is part of Freightliner’s engine evaluation fleet, and it’s been running over 500 miles a day around the state of Oregon in order to validate the design improvements to the 2007 version of the MBE engine. At 102,000 miles, it felt as tight as new, and on our little test jaunt, that engine made pretty short work of the 62,000 pounds it’s been dragging around since the spring.

Work began on the 2007 version of the MBE 900 back in 2003, and much of the effort since then has been directed toward strengthening the product line, says Detroit Diesel Corporation (DDC), not just gearing up to meet the ’07 EPA rules.

In previous incarnations, the MBE was available in four and six cylinder versions. The ’07 version is a single platform, 7.2 L in-line-six block, with variations in the peripherals making up for the performance differences. The standard engine features a single-stage turbocharger, and cast-iron block and head, with ratings from 190-250 hp (2,200 rpm) and 520-660 lb ft of torque at 1,200 rpm.

The high-performance version features a compact graphite iron (CGI) block and head, along with a dual-stage turbo. Power ratings run from 260-350 hp (2,200 rpm) and 800-860 lb ft of torque at 1,200 rpm. (The 350 hp version is for fire, EMS, and RV applications only, sorry.)

Both versions are available with two engine brake options; an exhaust brake producing up to 110 retarding horsepower, or a combination exhaust and compression brake that can bring up to 215 hp to bear on the braking effort.

The next generation of DDC engine electronic architecture, DDEC VI, manages turbo response, multiple injection events, aftertreatment service, and much more. It’s a more comprehensive electronic system, and it will be fully compatible with the Series 60 in terms of diagnostic hardware, codes, etc.

Cooled EGR remains the NOx reduction strategy — just more of it, coupled with an aftertreatment device to manage soot.

Passive and active regenerations will be required on a daily to weekly basis — depending on the engine and the application — and may require driver initiation or inhibition. Physical cleaning may be required between 200,000 and 400,000 miles, starting with Stage 1 cleaning, an on-vehicle compressed air cleaning that could take between two and three hours.

Stage 2 cleaning involves flushing the filter in a liquid cleaning solution, off the vehicle. In most cases, a reman filter will be exchanged at the time of service. In the two or so hours we had the truck — mostly stop-and-go driving around the city of Portland — a regen event was not required.

Between the Curbs:

Three-hundred horsepower is pretty good performance from a 7.2 L engine, and while the torque numbers might seem a little light, at 62,000 lb GVW, I can’t say I found it wanting. We pulled a few decent urban grades, and it shone. It gets up to speed in a real hurry — with much of the credit going to the two-stage turbo. Having said that, the turbo is very driver friendly. That is, it snaps to attention when it’s needed, but it’s not overly aggressive.

The gear steps of the Eaton 10-speed direct we had was ideal for this environment, though I suspect many of these trucks will be spec’d with automated or automatic boxes when they hit the street in January 2007.

Among the strong points of the engine is its quietness. Both in the cab and outside the vehicle, the MBE 926 was downright unobtrusive. Drivers will like that, and so will the folks watching it go by from the curb. The engine brake deserves a mention, too. It lives up to the billing, but you’ll hardly notice it’s working — another plus in an urban environment.

Expect an up-charge of between $4,500 and $6,000 for the MBE series engines, but you’ll find similar increases anywhere you look this year.