INSIDE THE 1,000 LB-FT 6.7L CUMMINS
The 1,000 LB-FT 6.7L Cummins engine's interior
Now that the cat is out of the bag and we know the high output 6.7L Cummins delivers 1,000 lb-ft of torque—the greatest ever produced by an OE engine scheduled for a pickup truck—time it's to investigate what efforts Cummins has taken to ensure that this power plant is as resilient as its forerunners. Does the famous I6 still have the available four-digit torque to travel a million miles? We won't know the million-mile solution for some time (we're told they won't be available until May anyway), but we can tell you that nearly every area that is essential to this engine's long-term life has been strengthened or reinforced with stronger parts.
The compressed graphite iron block, forged connecting rods, upgraded cylinder head with larger head bolts, and all the supporting components show that Cummins constructed this engine with longevity in mind. In fact, there is opportunity for expansion in the future. A larger variable geometry Holset turbocharger (with a forged-milled compressor wheel) delivers more than 30 psi of boost, hydraulic lifters eliminate the need for routine valve adjustments, and a higher pressure Bosch common-rail injection system yields the cleanest emissions to date. For a detailed examination of each element that goes into making the 6.7L Cummins the king of torque, keep reading.
Return of the Ram 3500 HD to the Top
With the high output 6.7L Cummins, Ram has formally defeated the Big Three in the race to 1,000 lb-ft. Furthermore, fully equipped 3500 variants have a class-leading 35,100 pound towing capacity.
Larger Block
A compacted graphite iron (CGI) crankcase from Tupy is now available for the high output 6.7L Cummins, which is perfect for the increased cylinder pressure this engine probably experiences over prior models. This is the first time the engine has never been built with gray cast iron. Increased hardness and fatigue strength, better ductility and improved tensile strength, as well as significant weight savings, are all benefits of casting a block from CGI (this block is 60 pounds lighter). Although the specific figures for the Cummins crankcase are unknown, we do know that CGI can be up to 75% stronger than regular gray iron. Four-bolt main caps hold a, stronger alloy crankshaft with a 10-bolt crank flange inside the deep-skirt block.
Lighter and Lower Compression Pistons
The durability is increased by cast-aluminum pistons with low-friction rings and lighter rotating assembly parts with larger wrist pin sizes. The H.O. The mill's compression ratio has decreased from 17.3:1 to 16.2:1. The fact that Cummins has returned to using forged-steel connecting rods (rather than powdered metal) underneath the pistons further supports our idea that this engine was built with lots of room for future expansion in terms of both horsepower and torque.
Changes to Cooling and Oiling
With 17 or more tons in tow and four digits of available torque, both the cooling and oiling systems have been enhanced to ensure optimal operating temperatures and lubrication. It is probably certainly equipped with a bigger radiator, a stronger engine fan, and a larger oil and water pump. Ram asked that the housings for the water and oil pumps also be made of aluminum to further minimize weight.
Huge head bolts
We may assume that the head bolts holding the cylinder head to the CGI block have larger diameters even though we don't have access to the exact measurements. Our educated guess is that Cummins altered the head bolt diameter from 12mm (left) to 14mm (right). The larger diameter fasteners will be crucial for maintaining the head gasket for hundreds of thousands of kilometers with increased cylinder pressure.
Rolling hydraulic lifters
The largest advancement is this engine's usage of hydraulic lifters in the valvetrain, a first for the 6.7L Cummins. Because solid roller lifters are self-adjusting, their removal causes the valvetrain to operate more quietly, extends the life of the valvetrain and cam, and prevents valve running after 150 000 miles.
Heads and rockers
As you may have assumed given the existence of hydraulic lifters, the rocker arms have no clearance for valve adjustment under the valve cover. The head itself still has 24 valves per cylinder with cast-iron construction, and has modern exhaust valves and stiffer valve springs to better tolerate the increased heat.
Greater flow of turbo
It uses a Holset variable geometry turbocharger, which is slightly different from the HE351VE turbochargers used on older engines, to deliver 1,000 lb-ft of torque at just 1,800 rpm. To improve exhaust flow, taller turbine vanes are employed in the exhaust housing, and the middle section uses stronger load bearings. For improved efficiency on the compressor side, a forged-milled compressor wheel is utilized, which is said to measure the same 60mm at the inducer. At full power, the Holset can produce 33 psi of boost right away.
