47RE Duramax?
02-05-2009, 05:07 AM
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47RE Duramax?
Starting on page 104 of the new Diesel Power (March 2009) is the article on a 2003 Chevy Duramax. What caught my attention is that the owner decided to go with a built 47RE Dodge tranny instead of the Allison. 
02-05-2009, 03:15 PM
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On a Duramax thats serious about racing and going fast, its not unheard of. Allison doesnt shift as fast as the Dodge transmission does, due to the cltch-on-clutch design. Its lighter than an Allison. Less rotating mass I believe.
02-06-2009, 10:30 AM
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here is my own dumb opinion:
drag racing with all out hp and most reliable repeatable performance: dodge tranny WITHOUT QUESTION
towing heavy loads all day: allison
daily driving: allison
drag racing slower than ~11.50 and less than 850rwhp: allison
there are not that many duramax's that would benefit from this, but the ones that are above this level benefit hugely from the "Duraflite". Buck and Jess dropped something like .3 of a second off their ET just by switching because the ratios in the 47re are so much better for racing.
ben
drag racing with all out hp and most reliable repeatable performance: dodge tranny WITHOUT QUESTION
towing heavy loads all day: allison
daily driving: allison
drag racing slower than ~11.50 and less than 850rwhp: allison
there are not that many duramax's that would benefit from this, but the ones that are above this level benefit hugely from the "Duraflite". Buck and Jess dropped something like .3 of a second off their ET just by switching because the ratios in the 47re are so much better for racing.
ben
02-06-2009, 12:15 PM
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For most of the people on this board, I would say that the allison is a better transmission. Depending on the year, it has 1 or 2 more gears which are very helpful when towing. It is also a very stout transmission that does what it is designed to do in stock form.
The big advantage to the dodge trannies is in drag racing. It is due to both the general design but also the number of gears. You don't need all of the gears that the allison has for drag racing an empty truck and gear shifts cost you time.
The big advantage to the dodge trannies is in drag racing. It is due to both the general design but also the number of gears. You don't need all of the gears that the allison has for drag racing an empty truck and gear shifts cost you time.
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02-06-2009, 12:58 PM
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Ben (duratothemax) can correct me on this if I am wrong, but I am pretty sure it is because the overall gear ratios are lower than in the 47RE.
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John_P
02-06-2009, 01:34 PM
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here is my own dumb opinion:
drag racing with all out hp and most reliable repeatable performance: dodge tranny WITHOUT QUESTION
towing heavy loads all day: allison
daily driving: allison
drag racing slower than ~11.50 and less than 850rwhp: allison
there are not that many duramax's that would benefit from this, but the ones that are above this level benefit hugely from the "Duraflite". Buck and Jess dropped something like .3 of a second off their ET just by switching because the ratios in the 47re are so much better for racing.
ben
drag racing with all out hp and most reliable repeatable performance: dodge tranny WITHOUT QUESTION
towing heavy loads all day: allison
daily driving: allison
drag racing slower than ~11.50 and less than 850rwhp: allison
there are not that many duramax's that would benefit from this, but the ones that are above this level benefit hugely from the "Duraflite". Buck and Jess dropped something like .3 of a second off their ET just by switching because the ratios in the 47re are so much better for racing.
ben
02-06-2009, 04:48 PM
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the 47/48re's gear ratios are nowhere near ideal for keeping the cummins in its proper torque/rpm range, thus the trans has to keep shifting up and down making it feel kinda clunky and not as seamless as maybe an allison does... A diesel has a much narrower rpm operating range than a gas engine, so therefore it NEEDS very strategically spaced gear ratios and shift points.
JMO
ben
02-06-2009, 09:11 PM
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because the gear ratios/spread in the allison is actually designed for a diesel engine.
the 47/48re's gear ratios are nowhere near ideal for keeping the cummins in its proper torque/rpm range, thus the trans has to keep shifting up and down making it feel kinda clunky and not as seamless as maybe an allison does... A diesel has a much narrower rpm operating range than a gas engine, so therefore it NEEDS very strategically spaced gear ratios and shift points.
JMO
ben
the 47/48re's gear ratios are nowhere near ideal for keeping the cummins in its proper torque/rpm range, thus the trans has to keep shifting up and down making it feel kinda clunky and not as seamless as maybe an allison does... A diesel has a much narrower rpm operating range than a gas engine, so therefore it NEEDS very strategically spaced gear ratios and shift points.
JMO
ben
