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ChevyZ71LTZ

Exhaust note of the 2.8L Mini-max

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Gas is $1.79 here.

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Gas is down to $1.66 here.

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I guess you haven't heard about the 2014-2015 5.3L? I get between 21 and 22 mpg average all around driving until winter blend gas comes along.

 

Gas here is down to $1.95, and diesel is like $3.59. Where is the economy, when you consider the difference in price?

 

My daughter and I have been looking at Colorados/Canyons. She wants the 3.5 L gas in a Z71 4x4 CC LB. I asked her if she wanted to wait until next year when they come out with the diesel? She looked at me like I had 3 heads, and said what would I want one of those noisy, stinky things for? She is 25, but she is a Scientist, and a whole lot smarter than the old man.

 

So, what would be my argument? Other than the cool factor?

 

My response would be 30 mpg!

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And probably more, if one does a tune to disable EGR. Green Diesel Engineering did the 2.8L VM engine in my 2006 Jeep Liberty Diesel, the same motor this little Dmax is based on. Talked with them recently and they are getting a 2.8 Dmax Colorado in and going to work tunes up. They confirmed my suspicion that the Dmax is essentially the original VM Motori 2.8L with some minor changes. Up until 2013 GM owned a big chunk of VM and the chief designer for the 2.8L Dmax came from VM. GDE does great tunes for these little diesels. The downstream stuff doesn't really concern me, but if I had one of these Dmax's I would shut off EGR first thing via a tune. I did on my VM 2.8 and it was a world of difference in better mpg and cleaner oil. That one had a average mpg of 32 in the Jeep Liberty. Not sure why a Colorado 2.8 couldn't pull similar results or better. The Jeep Liberty diesel weighed in at 4800 lb empty.

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On 12/22/2014 at 10:03 PM, Cowpie said:

Yeah, I have heard of the 2014 and 2015 numbers. Still not all that impressed when you figure that it is only a few mpg better than my 1979 Ford 351M engine in a full sized Ford Bronco, lifted. Now we are talking about over 3 decades difference in time, yet the base line has barely moved. Given technology differences... the 351 only had electronic ignition, carburetor, 4 speed manual, weighed in more than the typical Silverado crew cab, and got 17-18 mpg. So we come forward 3 decades, ECM controlled engines, direct injection, tuned intake and exhaust, smaller displacement (328 CI vs 351 CI) and I really am not moved with what the R&D folks have done.

 

Then you take a look at commercial semi trucks. Typical in 1980 was 5 mpg. Now... high 7 mpg's is very common, with the mystical ceiling of 10 mpg already being pushed (actually being broken in some recent cross country testing). That is a 50% or more improvement in fuel economy. Same loads, same roads, same fuel, but larger trailers now (53' today vs the older 45'). So today's 1500 pickups should be in the high 20's, on a bad day, to even be keeping pace with what is going on elsewhere.

 

Most folks are still in an 80's mindset regarding diesels. They don't stink, they don't smoke, they are cleaner out the tail pipe than most gas engines nowadays. They are environmentally a totally different critter than just a decade ago. The have lower NOx emissions and lower particulate emissions EPA standards than the gassers. And they get, usually, 50% better mpg than a gasser. Tell your daughter, "what's not to love about a modern diesel?" Same power out of half the engine displacement, better fuel economy, longer engine life. I firmly believe from what my digging around has come up with, the new GM 2.8L Duramax is based on the VM Italy 2.8L diesel, and that engine was designed so that less than 50% of them would need a overhaul by 300K miles / 500K KM.

 

And keep an eye out for E85 specific engines. Cummins has a 2.8L inline 4 E85 engine that compares favorably with the 2.8L Duramax diesel. Ricardo (an engine designer that has worked closely with GM over the years) has a 3.2L E85 engine just about ready for production by any OEM that picks up on it, that has the same hp and torque of the 6.6L Duramax diesel. Why GM or any other pickup OEM can't seem to get it together in a serious way regarding mpg with gassers is a mystery to me.

Agreed.  My our '79 F-250 4x4 400M 4-speed manual with 4.10 gear got 12mpg.  My '79 Trans Am 400 4-speed manual 3.23 gear gets 12mpg.  And guess what my '09 Silverado 1500 4x4 5.3L 6L80E 3.42 gear gets in town?  12mpg.  

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Tales of high MPG rusty Fords aside, I figured it was worth it to move from my 2015 5.3 to a 2016 2.8 Duramax. Diesel is 30 cents more than regular unleaded here, but when I'm getting 25-28 mpg, who cares?

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