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I just had a brainstorm.... tell me if you think any of this is right or if I'm way off base.


I want the most engine life I can get, and people are always talking about the long life of the Cummins. But, I think power levels have a lot to do with this. These million mile Cummins diesels that they point out are probably from back when it was only about 175 HP, not near the 300+ that all the diesels have today. That engine was probably only designed for 150 or so, and the highest it has in the medium duty trucks is about 250. The same is true for the Powerstroke. It is only about 250 in the medium duty trucks. So, these engines are turned up quite a bit in the pickups. I have to think that affects engine life. But the Duramax was probably designed for the 300+ HP that it has now. That tends to make me think it might do better at handling that power for longer.


So, am I looney for thinking about it this way? Does it make a difference?
 

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My opinion is that it won't be stock horsepower that determines the lifespan of a motor, but rather the amount of friction sustained over a fixed amount of milage. A motor with lower RPM at the same MPH should have the longer lifespan all else being equal. This of course assumes the motor is running within its powerband, and is well maintained.


That being said, I think the Cummins would out live the Duramax, if geared appropriately being that is makes more low RPM torque.


Do I care? No. I want the best riding truck, and the most HP potential.
 

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Cummins makes the B series engine in versions all the way upto 350 Hp IIRC. They were designed for that power level for the marine industry so I don't think they will have a short life in the pickups, but the D-max is going to give it some good competition.
 

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The Cummins that I drive at work runs at about the same RPM as my Duramax, and higher with a trailer. It has less torque at any usable RPM (above about 1200) and so it has to spin faster to do the same work. I have driven the newer and more powerful versions, but not enough to make a good comparison. --SS
 

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I guess I look at it this way....when was the last time a vehicle "died" becuase of a mechanical failure of the motor? I mean throwing a rod or breaking a crank or valvetrain? Most modern motors are so overbuilt for the application that actual mechanical failures of the motor are rare.


I had a 1990 half ton 4x4 chevy that had 190K on it when I sold it, that old Gen II 5 liter was smoking a little on startup but still ran like a champ. The only reason it smoked was because I ran a syn oil on a motor designed for dino. Valve guides got a little loose.


That truck was a true beater, all that stuff you see new trucks doing on commercials (dropping heavy objects from a height, loading with a payloader, driving off 6 foot embankments) it what i did with that truck, and oh by the way I rolled it in the middle of a seasonal use road. Flipped it back over (with a tow truck) and drove it home.



The leaf springs were broken, body all crumpled on one side, tires bald, stearing was looser than a french whore, BUT the radio worked and that darn engine just wouldn't quit! Burned some oil but always put in a full day.


Million mile cummings or not, the rest of the truck will die long before the motor comes apart. Unless your making 900 hp, then all bets are off.
 

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Amric said:
I want the best riding truck, and the most HP potential.
If that's your preference the GM wins in my opinion. Except maybe HP potential unless you tie it to cost.
 

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hoot said:
Amric said:
I want the best riding truck, and the most HP potential.
If that's your preference the GM wins in my opinion. Except maybe HP potential unless you tie it to cost.

OUCH! Yeah, that is fast becoming frustrating. The lack of performance parts for the Duramax is pathetic. Hopefully the situation improves, but the emissions equipment present on the newer trucks may prevent vendors from ever participating in such a market. There was (and is) a real opportunity with the LB7, but that window of opportunity will pass as these trucks are retired.


I guess if your serious you should buy an old 12 valver!
 

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I've never worn and engine out. The closest I came was my ancient Volvo, which had 250,000 miles on it when a girl friend wrecked it. Now, I admit that at 86k I did the valves, rings and big end bearings, but it ran the original mains until its untimely demise. I ran the hell out of it throughout its life. If the Duramax can't beat that it ain't worth shiite.


TC
 
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