my question is what the reasonable time or how long can I drive and should I even be keeping the rpm that high....I know some of us like to hit the 150km/h when passing some peeps on highways I'm wondering how long can you keep pushing that speed since the rpm is like 3000-3200rpm....no gauges running stock and no load.....I have taken 145 for 30/45 min one time and did not see any changed on the preshure or temps....any sugestions on how damaging is to diesel high rpm...thanks

i will tell you that i do a trip 200km, to the usa, evey so often, no traffic at all on that road, and flat as a pancake, i ussally go in the 175 to 200km/hr period, or 3000 to 3500 rpm, their and back(2hours at that speed) and other than using alot more fuel than normal, everything seems to be fine, you must still have the 245 on, at that rpm

yeah the max is 156km/h tops...and I suspect you have the govener out to be able to go that speed

Higher RPMs should affect something long term. I am GUESSING. Just from a common sense perspective. The harder you use something, the more likely that the lifespan will be shorter.

I would guess that it would affect the lower end (main bearings) Maybe post in the Tech section.

As a heavy equipment operator I run a CAT track loader that runs wide open for hours on end. We've had track loaders go 20,000 hours with out major problems. I know the CAT engine in our loader is not a duramax but the max is a diesel that is build very heavy duty. I think, and I could be wrong, as long as you are under load it should be fine. Being in park and holding the pedal to the floor is a differant story. At the same time Max Owner you make a very good point.

I think towing 15,000 lbs at 70MPH would be a lot tougher on the dmax than running at 3200RPM on the highway. I tend to equte wear to fuel usage. Running at 110MPH I'm betting you're still getting 13-14MPG and using nowhere near the fuel/power compared to towing 15K (and probably getting 9-10MPG). Plus the engine is warmed up and running basically at one RPM, with good oil pressure and high coolant flow. I don't think you're causing any undue wear. Now pulling the 15K at 110, that MIGHT cause some wear!

These trucks re designed to use the full rpm scale.
I would think the one thing you would want to do for long trips at high rpms would be to change your oil more often than on a regular basis.
Also use some of the better brand oil when doing this. The braking down of the oil will cause a lot of the problems that have been addressed.
But like Max Owner said. These trucks are being used for alot of different reasons than what they were designed for. It is not normal practice to drag race a 6000 lb vehicle, but there are after market goodies to help with that.

I know gas and diesel engines are very different, but lets compare. Some gas engines rev to about 3000 rpms on the freeway doing 80 or ninety. I dont think that revving our engines that high is going to do any damage. Also, if our engines are built stronger we should have no problems.

If you don't exceed the factory governor speed you should be fine. That is the whole purpose of the governor. Think of wear on the engine as if you have only so many revolutions before it wears out. If you do it slow or fast it will wear the same as long as your oil and cooling system are doing their jobs properly. Now the amount of wear per revolution will vary depending on engine load. Revving up the engine in neutral compared to hammering down at the truck pulls are two different things all together. Power is pushing the piston down when there is resistance to it. The more resistance, the more power, or bigger explosion, is needed. The more power you use the more wear you cause. Remember, you engine will only make enough power to get the job done. That is why you have to load the dyno to get peak HP numbers, or effectively run the truck to it’s limits. That is also why a 600 HP truck will have much better ¼ mile times than a 300 HP truck. A 600 HP truck can get the truck moving faster. Flying your unloaded truck at those speeds is not hard work for your engine. Getting to those speeds in a hurry is.

I remember talking to Steve(socaldmax) at the socal dyno days and he said they test these engines well above 3500 rpm(I think he said 4000 or 5000rpm not sure) for 6 hours or something like that. The whole motor is stout especially the bottom end. I don't thing you will do much damage if any at 3500 rpm sustained. Just my .02

LA DMAX