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| Apparently you've never heard of internal EGR. On some Tier 3 engines the exhaust valve opens at the bottom of the intake stroke to allow some exhaust back into the cylinder. This happens before the intake valve closes. This reduces the normally over-oxygenated diesel combustion process and reduces NOx. Unfortunately it also increases heat rejection to engine coolant, but the EPA doesn't mind that.
Turbos don't have to spin to fail. even a frequent oscillation back/forth on dry bearings can begin to form tiny flat spots on bearings, eventually causing a failure. The sock or duct tape on an exhaust stack is the best way to assure that turbo rotor movement is ZERO, or at least minimized. Like someone else said, cheap insurance. | |
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Covering exhaust pipe
