A stronger Duramax turbodiesel engine will be available on Heavy Duty GM trucks starting next year. Thanks to numerous improvements, the V8 will now make 360 hp at 3,000 rpm and an incredible 650 lb-ft of torque at just 1,600 rpm when ordered with the Allison automatic transmission.
The Allison 1000 has also been upgraded with a second overdrive gear so trucks can cruise at 60 mph while making just 1,550 rpm. It also includes a thumb-activated shifter, and cruise control grade braking that will automatically downshift to maintain a steady speed on downhill grades.
So what did the engineers do to increase the Duramax output by 50 hp and 45 lb-ft of torque while making the engine run smoother, quieter and cleaner? They changed a lot of things, such as:
-Improved block casting and machining
-Upgraded bearing materials
-Pistons designed to lower compression from 16.8:1 from 17.5:1
-Increased piston bore diameters
-Thicker connecting "I" rods
-Revised cylinder heads for the new compression settings
-Maximum injector pressure increased from 23,000 psi to 26,000 psi
-Higher pressure fuel pump
-New seven-hole fuel injectors that spray directly on improved glow plugs
-A smoother and more efficient turbocharger
-Quieter air induction system
-EGR with a larger cooler for more airflow
-New 32-bit E35 engine controller for better efficiency and lower emissions
-Added a 600-watt grid heater in the intake to reduce smoke during cold and light-load driving
| Duramax 6600 6.6L V-8 (LBZ) | Specifications
|
| Type: | 6.6L V-8 |
| Displacement (cu in / cc): | 403 / 6599 |
| Bore & stroke (in / mm): | 4.06 x 3.9 / 103 x 99 |
| Block material: | cast iron |
| Cylinder head material: | cast aluminum |
| Valvetrain: | OHV |
| Ignition system: | compression, glow plug start aid; low-resistance spark plug wires |
| Fuel delivery: | direct injection diesel with high pressure common rail |
| Compression ratio: | 16.8:1 |
| Horsepower (hp / kw @ rpm): | 360 / 268 @ 3200 (auto trans) |
| Torque (lb-ft / Nm @ rpm): | 650 / 899 @ 1600 (auto trans) |
| Recommended fuel: | diesel |
| Maximum engine speed (rpm): | 3250 |
| Emissions controls: | turbocharged, intercooled, catalytic converter system |
| Allison 1000 (MW7) |
|
| Type: | 6-speed automatic |
| Gear ratios (:1): |
|
| First: | 3.10 |
| Second: | 1.81 |
| Third: | 1.41 |
| Fourth: | 1.00 |
| Fifth: | 0.71 |
| Sixth: | 0.61 |
| Reverse: | 4.49 |
| Final drive ratio: | 3.73 ratio standard on all models |