Re: Cummins C8.3 325 hp running too warm Reply #50 – August 19, 2020, 02:02:21 pm Poorer grounds. Frame grounds versus decicated green ground wires. Quote Selected
Re: Cummins C8.3 325 hp running too warm Reply #51 – August 19, 2020, 02:31:20 pm Quote from: Pamela & Mike – August 08, 2020, 09:41:15 amJohn,The Detroit 6V92 has a supercharger/blower not a figure of speech.MikeSupercharged is a physical condition, that is, air is delivered to the cylinder at a pressure above ambient.The blower on a 2-cycle Detroit supplies scavenging air to replace the intake stroke. The turbo supplies the supercharging. A blower on a 4-stroke engine can function as a supercharger. Quote Selected
Re: Cummins C8.3 325 hp running too warm Reply #52 – August 19, 2020, 03:01:07 pm Supercharging: A supercharger is an air compressor that increases the pressure or density of air supplied to an internal combustion engine. This gives each intake cycle of the engine more oxygen, letting it burn more fuel and do more work, thus increasing power.The Roots blower/supercharger on the Detroit 6V-92TA is a positive displacement compressor/pump. A turbocharger is a centrifugal compressor/pump. Turbos may be installed in pairs in parallel or series and can take advantage of the additional pressure when mounted in series (compound turbo) Unlike a positive displacement, they must be spinning quite fast to increase the pressure.Fire trucks use centrifugal pumps for their main water pumps. Off road fire trucks may have PTO positive displacement pumps to enable them to pump water while moving a slow speeds. The 6V-92TA has a valve so once the boost pressure is high enough, it bypasses the Roots blower and the boost goes directly to the engine.Instead of an intercooler (CAC), the Detroit has an aftercooler mounted UNDER the Roots blower to cool the incoming air charge. It is liquid cooled from the engine's cooling system. The cooler the engine coolant is, the cooler and denser the incoming air to the engine will be. Some CATs have aftercoolers.Turbos may also be liquid cooled. Liquid cooling is always more efficient than air cooling so the cooler may be much smaller in size.A look at the EMD two cycles on railroad locomotives shows how the engine was redesigned several years ago and the Roots blower was removed. Large electric motors were installed on the turbos to bring them up to high speed so the 2 cycle engines would start. This is why the big ship 2 cycles have up to 55 percent efficiency. No loss from a positive displacement pump/compressor.Pierce Quote Selected
Re: Cummins C8.3 325 hp running too warm Reply #53 – August 19, 2020, 11:47:44 pm The role of the blower on this (or any other 2 cycle Diesel) is to produce scavenging airflow. This is not supercharging, as the blower's capacity is carefully matched to the engine displacement so that a slight amount of positive air pressure is produced in the cylinders during the scavenging phase.Talk:Detroit Diesel Series 71 - Wikipedia Quote Selected
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