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Discussion Starter #1
i purchased a Colorado LT long box with the 2.8
Strange motor as it doesn’t want to rev. It falls on its face as the rpm climbs towards 3k.
Cool that it doesn’t downshift on all the hills like a gas engine.
It seems to get up to speed ok but the power band is very narrow..

We have 2 Duramax v8s at work and a new Ford Platinum Powerstroke
Both the Duramax and the Power Stroke pull hard past 5k. There is no sign of power fall off as the rpm climbs.
I have also driven a VW Diesel and it revved like crazy..

It reminds me of a gas engine with a plugged cat.

How about you guys. How do your trucks work....

I ask because I just bought a Grey Wolf 19RR and I have concerns about this truck pulling it..

Rob
 

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Trailer is like 4500#? It'll haul that no problem. There's really no way to compare the Duramax v8's to this little 4 banger...they share the Duramax badge, but the buck stops there. It's a good little engine, but it's not gonna haul ass at 5k RPMs all day, it stays under 3k most of the time for me.
 

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Just remember, it's not a race truck, it's made for fuel efficiency and decent towing for a mid-size truck...
 

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You need to review a tuned Colorado, i became super impressed after my sport/economy tune.
My 12” wide tire chirp Whenever the light turns green.
On the highway she’s a passing beast!!
 

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Hook up that trailer and do a test pull around town. Then you’ll know how she tows it. 4500 lb is well under this trucks sweet spot, that’s where it shines. The shine starts to fade over 6000 lb trailer...
 

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Discussion Starter #6
Well what I have been doing is running it very hard for the last couple of days....
And it’s made a big improvement.
It’s getting better. Today I pounded it fairly hard. Wide open starts, a few burn outs ect

It started to rev more freely and felt like it was pulling a lot harder as it hit 3k.

I pick the trailer up Thursday and bring it home and then i take it 300km for 2 days then back home.

4300 lbs dry. Add 40g water, generator, food, clothes, propane, batteries, prob at 5200.
 

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I have zero clue what good is going to come out of burnouts and wide-open throttle times...then again, what do I know...
 

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If you have a brand new truck, say it has less than 1,000 miles on it, it's still getting broke in. I think mine finally felt like it was broke in when I got somewhere between 5,000-10,000 miles.

If you mash the pedal from a standstill, the truck will fall on its face. It will creep forward and then finally lunge forward as things catch up. if you give it about 1/3 to 1/2 pedal it will pick up better and then you can roll into the pedal more and it will take off.

Or you could just tune the truck and when you mash the pedal, it will take off with no hesitation. It will give you more driving confidence. It won't really extend the ability to pull your trailer (as you don't want to overload the weight rating on the truck), but it will get up to speed and stay at speed better than it will stock.
 

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The only time my truck has revved past 3k is when the exhaust brake has kicked in. Otherwise, it doesn't make any useful power above that range, even when towing.
 

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Yeah, i'm also baffled why anyone would do burnouts and wide open throttles, particularly for a truck which perhaps hasn't even gone through break-in mileage(?). Also baffled at why folks think a 2.8L diesel should act like a 5-6 liter diesel. Marketing always exaggerates (that's their job), so whatever Chevy says about the 2.8's tow capability, just cut that number by perhaps 30% to arrive at something realistic (that's a lesson on being an informed consumer in any market).
The 2.8D seems to be quite happy between 2k-3k, and it leaves V8 gas trucks in its wake when powering up the steepest high altitude grades (where natural aspiration falls short, while our turbos just keep gulping and delivering). I've engine braked down long Colorado rocky highway grades, in 3rd or 4th gear, at perhaps 3500 rpm (the exhaust brake doesn't seem to kick in until conditions are quite extreme, so I haven't bothered with it much), but I wouldn't even let it get over 4k - because I'm observing its inherent capabilities and limitations. Why force it to do something out of its typical operating range?
 

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"I've engine braked down long Colorado rocky highway grades, in 3rd or 4th gear, at perhaps 3500 rpm (the exhaust brake doesn't seem to kick in until conditions are quite extreme, so I haven't bothered with it much)"

Mine does, JDB. I wonder if it's because I use the cruise. I find the downshift/jake braking quite smart. Works seamlessly, and probably does the job better than I could manually. I DO shift down on the grades you mention, but the truck knows what to do from there....
 

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Discussion Starter #14
@OP/Rob - don't ever tell a dealer how you've been running that 2.8D so hard.
Something tells me it had a very hard break in. It had 200 miles on it when I bought it. I bet everyone at the dealership had it out. And many prospective buyers.

In my other post I mentioned that it doesn’t rev very high. And every other diesel I have driven reved much higher.
I wasn’t talking about power as in the 6.6 or the 6.7
I was talking rpm.
 

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"I've engine braked down long Colorado rocky highway grades, in 3rd or 4th gear, at perhaps 3500 rpm (the exhaust brake doesn't seem to kick in until conditions are quite extreme, so I haven't bothered with it much)"

Mine does, JDB. I wonder if it's because I use the cruise. I find the downshift/jake braking quite smart. Works seamlessly, and probably does the job better than I could manually. I DO shift down on the grades you mention, but the truck knows what to do from there....
It's not a Jake Brake, it's VGT exhaust brake - they're very different. A Jake Brake opens the exhaust valve at the end of the compression stroke, before the power stroke to bleed off cylinder pressure - basically turns the engine into an air compressor. The VGT exhaust brake in our trucks closes the turbo's vanes to create back pressure in the exhaust, so the engine is basically compressing on the exhaust stroke, too.

Also, because these engines have a compression ratio of 16.5:1, the effect of normal engine braking is more pronounced than with a gasoline engine, and that's most of what you feel when you let off the accelerator and the truck downshifts while coasting downhill. It's not until you have a large negative load on the engine (such as a heavy trailer helping push you downhill as you decelerate) that the effects of the exhaust brake are really noticeable.
 

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It's not a Jake Brake, it's VGT exhaust brake - they're very different. A Jake Brake opens the exhaust valve at the end of the compression stroke, before the power stroke to bleed off cylinder pressure - basically turns the engine into an air compressor. The VGT exhaust brake in our trucks closes the turbo's vanes to create back pressure in the exhaust, so the engine is basically compressing on the exhaust stroke, too.

Also, because these engines have a compression ratio of 16.5:1, the effect of normal engine braking is more pronounced than with a gasoline engine, and that's most of what you feel when you let off the accelerator and the truck downshifts while coasting downhill. It's not until you have a large negative load on the engine (such as a heavy trailer helping push you downhill as you decelerate) that the effects of the exhaust brake are really noticeable.
As an ex Seabee heavy equipment operator, I can comfortably say that jake brake is a generic term, Cliffie Clavin.......
 

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As an ex Seabee heavy equipment operator, I can comfortably say that jake brake is a generic term, Cliffie Clavin.......
Yeah... in the same way that "Vice Grips" is a "generic" term for locking pliers. Jake is short for Jacobs (ie. Jacobs Vehicle Systems), and so "Jacobs Brake" or "Jake Brake" is a proper noun.

Also, A Jake Brake and a VGT exhaust brake operate in entirely different ways as I mentioned... a Jake Brake bleeds cylinder pressure after the compression stroke and a VGT exhaust brake builds cylinder pressure and exhaust system pressure on the exhaust stroke.
 

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...The VGT exhaust brake in our trucks closes the turbo's vanes to create back pressure in the exhaust, so the engine is basically compressing on the exhaust stroke, too. Also, because these engines have a compression ratio of 16.5:1, the effect of normal engine braking is more pronounced than with a gasoline engine, and that's most of what you feel when you let off the accelerator and the truck downshifts while coasting downhill. It's not until you have a large negative load on the engine (such as a heavy trailer helping push you downhill as you decelerate) that the effects of the exhaust brake are really noticeable.
Super helpful @18Z71Minimax . I'm an engineer, so I appreciate knowing the technical difference. Yeah, just downshifting on the descent is quite effective - a lot of engine breaking effect and probably my highest revs since I let it get up there a bit. The one time I experienced the exhaust brake, it was a bit startling since I didn't have the extra inertia of a heavy trailer - it just seemed like too much braking since the slowdown was drastic and I was concerned about surprising the vehicles following us (they probably had to hit their brakes just to keep off my tail).
 

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Super helpful @18Z71Minimax . I'm an engineer, so I appreciate knowing the technical difference. Yeah, just downshifting on the descent is quite effective - a lot of engine breaking effect and probably my highest revs since I let it get up there a bit. The one time I experienced the exhaust brake, it was a bit startling since I didn't have the extra inertia of a heavy trailer - it just seemed like too much braking since the slowdown was drastic and I was concerned about surprising the vehicles following us (they probably had to hit their brakes just to keep off my tail).
I think it was someone from GDE, but I recall seeing something that said there's a fuel cutoff at something like 4500 RPM, but the rotating assembly is actually capable of like 5500 or 6000 RPM. I may be wrong on the exact numbers, but the engine will definitely spin faster and not come apart under deceleration as compared to how fast it'll allow it to turn under acceleration.
 

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The stock transmission programming actually revs the engine too much. The 2.8 is a low end beast - shifting it firmly and early works great. Buzzing it past 3,000 RPM is not effective.

My engine and transmission tuned truck is very smooth, does not seem that fast due to the economy of revs, but if the throttle is rolled in firmly, it pulls ahead and passes other traffic quite decisively without revving over 2,500. The effect is magnified at high elevation. At 10,000 feet on a nice 7% grade, all the other non forced induction traffic is in my way - she just keeps motoring at 70 mph in 6th gear ;)

All that said, our 2.8 is not a big block V8 diesel - those things are entirely different animals. The big boys can seemingly wrinkle pavement and tow a house, but they can't get 34 MPG on the highway. Unless one needs 900 pound feet of torque to pull something seriously heavy, those trucks do not make much sense as daily drivers.
 
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