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chadd
05-11-2006 05:03:38
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Re: Displacement on Demand in reply to AgED, 05-10-2006 21:09:52
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Yes, both the 1468 and 1568 with the DV-550 engine had a displacement on Demand system OF A SORTS. In the modern DOD system, the pushrods on the cylinders that are shut down are prevented from moving, or are moved over to a lobe on the camshaft with zero lift. In this way the valves remain closed, no fuel or air enters or leaves the cylinder, and the piston keeps compressing and decompressing the same air, making the air act as a spring. In the system for the DV-550, the valves continued operating just like normal, just that no fuel was injected into 4 cylinders by the injection pump under light load. The 1468 used cylinders 1, 4, 6, and 7 under light loads. On the 1568, they changed the injection pump to use cylinders 2, 3, 5, and 8 under light load. The system supposedly worked well, but farmers hated the weird sound it made on 4 cylinders and the engines just weren't as good tractor engines as the 400 series inline sixes. The DV-550 had poorer torque-rise, were a sleeve-less design (which made rebuilds more expensive), had a weaker bottom end, and was not designed for the dirty, high-stress conditions inherent in a tractor (the engine was designed for trucks, boats, and stationary power units). It was maxed out in a tractor at 165 horsepower, and could not withstand the stress of turbocharging. The DTI-466 in-line six went on to produce upwards of 185+ in the 5488. They weren't bad tractors, but they weren't any better than the cheaper 6 cylinders, and were more of an advertising tractor. I think they were one of the coolest looking tractors, though. Hope the info helps!
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