Drive: 2006 Dodge Ram 1500
Customer response to the 2006 Dodge Ram 1500 will be watched closely in the next few months as fullsize trucks come off a most impressive summer sales spree. Industry observers have to ask: Who’s left to buy a big truck? And if anyone is shopping this fall, will prices at the gas pump scare them away?
To complement news about the new Mega Cab model, the 2006 Ram 1500 has been given a midlife exterior facelift, interior freshening and upgraded frame and suspension. The changes should attract consumer attention as the fullsize offerings from Chevy, GMC and Toyota are finishing up their last year before redesigned models are introduced. Nissan Titan sales continue to eek upward with no major changes expected, but the truck is still wanting for a solid foothold in America’s breadbasket. The Ford F-150 should cruise along with only a few minor cosmetic changes this year.
Perhaps the most anticipated feature of the new Ram 1500 is the multi-displacement system (MDS) added to the Hemi engine. Dodge officials promise this new technology can improve fuel economy with no loss of power. With gas prices hovering near the $3-per-gallon mark in many areas now, even the most hard-crusted pickup enthusiast will be looking to lower his monthly running costs.
MDS allows the Hemi to transition from eight cylinders to four in just 40 milliseconds, which is quicker than the blink of an eye. The switch takes place when there’s little or no load on the engine, such as cruising the Interstate where engineers say it only takes about 20 or 30 horsepower to keep a vehicle moving. Long hauls on open roads with a steady speed should result in the most noticeable savings. Despite the promise that “customers will experience fuel economy gains of up to 20 percent under certain driving conditions,” Dodge didn’t change the EPA estimated fuel economy ratings for the 2006 Hemi-power Ram 1500 pickup. The 2005 and 2006 press materials state the EPA numbers as 14 city/18 highway for the 2-wheel-drive models and 13/17 for the 4WD trucks.
The MDS operation is very smooth. Unlike the Honda Odyssey minivan, which has a similar system that cuts out three of the engine’s six cylinders while cruising, there is no indicator on the dash to let the driver know how many of the Hemi’s cylinders are firing. Trying to determine when MDS kicks in or out is futile, even with the quieter noise levels in the cab. Stabbing the throttle off cruising speed offers normal acceleration and transmission kickdown.
The on-board engine-management computer controls the MDS. The four cylinders that can be deactivated are numbers 1,4,6 and 7. That includes the two inner cylinders on one back and the two outer cylinders on the opposing bank. By shutting down these specific cylinders at once, the engine can maintain regular 180-degree firings as a V4. Hemi engineers designed the cylinder block with a specific oil circuit to support MDS. Four solenoids control oil pressure to eight specially designed hydraulic-roller lifters that control the intake and exhaust valves in the cylinders to be deactivated. When the solenoids are activated, high-pressure oil is fed to the lifters. A pin in each lifter is moved, disconnecting the outer portion of the lifter from the inner. The outer portion of the lifter continues to ride along the camshaft lobes but the inner portion, which supports the pushrod, remains still. With both valves closed, the engine computer also shuts off the spark and fuel to those cylinders.