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cummins considered a medium duty engine?


jro909

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i know alot of ram buffs, and they swear by the cummins saying its a medium duty engine in a light duty truck, where as the powerstroke and duramax are just light duty diesels...my question is what sets the cummins apart? it dosen't look build any stronger then the other two :dunno:

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Yes in fact it is, I don't know the facts behind it but I was told this as well. I know a fella that pumped over 900 RWHP out of a stock bottom end p-pumped 5.9 litre on nitrous. Extensive head work and alot of cash put into the head...but rotating assembly remained stock and intact!! I mean he didn't drive around on a 900 HP tune all day. It ran like that for 10-12 seconds at a time...where as to my knowledge, a d-max can handle about 650...I have a soft spot for an old 12 valve cummins. Those trucks will run forever. Not a high performance piece of machinery but they will run forever...

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The simplistic answer to this question is design. The cummins is a torque monster creating torque through the long stroke of a inline six cylinder vs the short stoke of a V8. As far as duability is concerned, diesels need a incredible amount of compression to fire. The cummins cast iron design is far better equipped to handle this internal stress. The cummins makes peak torque at a much lower rpm than the powerstroke or Duramax. High compression along with high rpm equal a double negative. There is a reason semi trucks no longer build V8 diesels.

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They can say whatever they like but the fact is the modern versions of the Duramax are about as reliable as the sunrise. And as good as the Cummins might be, it's no excuse for the rest of the truck. :lol:

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had a dodge with a 5.9 just before my current truck. Engine was awesome!! the only problems i really had was with transmission and the truck its self. We have some older bucket trucks and diggers at work with 5.9L cummins engines, they are built up a little more of course with bigger transmissions and what not.

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a buddy of mine, my old room mate is in the air force and is vehicle maintenance. he gets in gm 6.5's and fords all the way from the 7.3 to brand new ones with issues but the cummins only come in for regular scheduled maintenance

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I'm a mechanic for a commercial tire store. Have been a HD diesel mechanic for 24 years and previously owned a 03 Dodge cummins 6sp manual. We have 3 commercial tire service trucks, 1 06 f-550 with a 6.0 and 2 C5500 Kodiaks with the duramax, all with approximately 115k miles on them. One 04 C5500 has had 2 turbos, head gaskets replaced and under a different warranty claim, they replaced both heads. Our other C5500 is a 05 and it has had 1 turbo and head gaskets replaced 1 time. I just replaced the waterpump on the 04 last month. Not sure if you have ever looked at a Duramax in a C5500 but it is a nightmare compaired to a pickup. This C5500 has also been into the dealer multiple times because when they did the Turbo, they pinched the injection wire harness. Finally had a different shop replace the entire engine wire harness at a cost of 2000 dollars. No way I was tackling that job. (once again, have you ever seen under the hood of a Kodiak). I won't even bore you with our F550 with the 6 liter other than to say it costs about 1000.00 a month in maininence between injectors, fuel injection control modules and turbos. These trucks have PM's done every 3k miles because they do alot of idling on site while the guys service the tires. My 03 dodge cummins in the 140k miles I owned it had a waterpump replaced, 20 minute job and I adjusted the valves once. Oil changes every 5k miles. I would not roll the dice on owning any diesel other than a cummins.

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so what i'm gathering here is that the cummins is considered medium duty because of how low of an rpm it uses to generate alot of torque...it makes me wonder why ford and gm still make v8 diesels then...

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it dosen't look build any stronger then the other two :dunno:

 

And you can tell this how, by looking at the valve cover(s)?

 

The Cummins while beefier in internal component size also turns a much lower engine speed because of this. Cummins engines are used in many medium and heavy duty applications as are Duramax's. The Cummins is based off of larger heavy duty engines of the same engine family so that is maybe why you've heard that but in their current applications, they are both more than plenty as far as durability goes.

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I unload alot of semis on a regular basis and most drivers say they would rather have a caterpillar :dunno: honestly i'm not biased as i don't own a diesel nor a semi-tractor

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