Volume 3 Issue 2 - Diesel Articles

Oil Pump Flow Increased

Increasing the oil flow through the engine follows the use of the enhanced main bearings discussed above. While it may not be an absolute necessary modification, it will probably save GM and GM technicians a lot of headaches from drivers worried about the oil gauge reporting low pressures. The oil flow through the main and connector rod bearings are key to the oil pressure reported on the dash. Just as any liquid will flow more easily and at lower pressure when it is flowing through a less restrictive space, increasing the size of main bearings means that the oil that flows through those bearings does so at lower pressure, unless you increase the flow. It seems likely that rather than cause panic among Duramax drivers when they see 15 PSI oil pressure, GM simply decided to increase the flow of the oil and, by doing so, maintain popularly acceptable oil pressure levels. In truth, high oil flow, as opposed to oil pressure, is the critical measurement for the well-being of the bearings. While it may seem to make sense that higher oil pressure would result in more clearance between the bearings and the crankshaft or connector rods and while that line of reasoning is accurate for bearings found in turbines, it is not true for the bearings used in the Duramax: so it is high flow, rather than high pressure, that improves performance. So, increasing the oil pumps capacity for the LML provides peace of mind for owners and simply peace for GM.

Increased Oil Pressure at the Turbo

By increasing the oil pressure at the turbo, GM pushes the oil through the turbo faster. At first, it might seem like this would limit the oil's ability to pull heat away from the turbo since it is spending less time than it would be at a lower pressure/slower speed. The opposite is true however. Just like a higher volume of water flowing over an ice cube will cause it to melt more quickly than a trickle, faster flowering oil means a higher quantity of relatively cooler oil running over the hot turbo, pulling the heat more effectively while it also spreads the heat that is removed over more oil so that the oil does not get as hot. So more oil at the turbo means more cooling capacity and less heat transported to the same amount of oil.

Modified Connecting Rods’ Pin Ends for Increased Piston Support and Higher-Strength Piston Design that Eliminates Bushings to Provide Lower Reciprocating Weight

More horsepower, more torque means that the engine components needed to be beefed up in order to handle the extra power. Modifying the pins and beefing up the pistons equips the new Duramax LML engine components to handle the increased power. The "higher-strength piston design" allows GM to produce a lower weight piston assembly so that each powerstroke can focus more on converting the energy from combustion to the crankshaft and be less occupied with using the same energy to power the motion of the pistons themselves. Just as the modified bearings resulted in a net lower drag with each turn of the crankshaft, the lower weight piston asembly means less energy is required to power the pistons themselves and more energy translated to the crankshaft.