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The Water Cooler
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Sweet, take a look at the 2013 RAM truck..
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<blockquote data-quote="Glocktogo" data-source="post: 1787752" data-attributes="member: 1132"><p>At some point I think the law of diminishing returns is going to kick in. So you're going 75mph in 8th gear at 1500 rpm. The MDS kicks in and four of the 8 cylinders stop producing power and become parasitic drag on the engine. The .38 Drag Coefficient kicks in and with the reduced available torque, speed drops off and the engine starts to lug. The cruise control (or your foot) compensates by pushing more fuel to the engine. This reduces fuel efficiency and at some point, either the transmission hunts a lower gear or the MDS shuts off to get more torque, possibly both. </p><p></p><p>My GS 460 in contrast has an ultra low .27 drag coefficient. All 8 cylinders produce power full time and it has 339 lb ft of torque at a relatively low 3600 RPM. The transmission never hunts and will hold 8th gear with gentle acceleration and all but the steepest inclines, even in a headwind. The result is actual real world MPG figures that exceed the EPA highway rating on a routine basis.</p><p></p><p>I had an 86' F-150 with a 302 and the AOD 4 speed auto trans. With the anemic torque produced by that engine, the transmission was constantly hunting and shifting. That led to terrible fuel economy and early transmission failure. I would've gotten better fuel economy and longer transmission life out of a C-6 three speed auto in that case. I think Ford tried to overdo it with a 0.67:1 overdrive ratio. They would've made a far better trans if they'd have been more conservative on the ratio, say 0.87:1 instead. The Dodge ZF unit will have a 0.667:1 ratio in 8th gear and a final drive ratio of 2.81. Coupled with a .38 drag coefficient and MDS, the 2013 Ram 1500 may wind up having great EPA numbers but poor real world observed mileage. I'd hold off on purchasing one until some real world figures start showing up. This may wind up being a paper Ram, but real world lamb. <img src="/images/smilies/frown.png" class="smilie" loading="lazy" alt=":(" title="Frown :(" data-shortname=":(" /></p></blockquote><p></p>
[QUOTE="Glocktogo, post: 1787752, member: 1132"] At some point I think the law of diminishing returns is going to kick in. So you're going 75mph in 8th gear at 1500 rpm. The MDS kicks in and four of the 8 cylinders stop producing power and become parasitic drag on the engine. The .38 Drag Coefficient kicks in and with the reduced available torque, speed drops off and the engine starts to lug. The cruise control (or your foot) compensates by pushing more fuel to the engine. This reduces fuel efficiency and at some point, either the transmission hunts a lower gear or the MDS shuts off to get more torque, possibly both. My GS 460 in contrast has an ultra low .27 drag coefficient. All 8 cylinders produce power full time and it has 339 lb ft of torque at a relatively low 3600 RPM. The transmission never hunts and will hold 8th gear with gentle acceleration and all but the steepest inclines, even in a headwind. The result is actual real world MPG figures that exceed the EPA highway rating on a routine basis. I had an 86' F-150 with a 302 and the AOD 4 speed auto trans. With the anemic torque produced by that engine, the transmission was constantly hunting and shifting. That led to terrible fuel economy and early transmission failure. I would've gotten better fuel economy and longer transmission life out of a C-6 three speed auto in that case. I think Ford tried to overdo it with a 0.67:1 overdrive ratio. They would've made a far better trans if they'd have been more conservative on the ratio, say 0.87:1 instead. The Dodge ZF unit will have a 0.667:1 ratio in 8th gear and a final drive ratio of 2.81. Coupled with a .38 drag coefficient and MDS, the 2013 Ram 1500 may wind up having great EPA numbers but poor real world observed mileage. I'd hold off on purchasing one until some real world figures start showing up. This may wind up being a paper Ram, but real world lamb. :( [/QUOTE]
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