I currently own a 2020 6.6 , 2018 6.0 , 2009 Duramax and 2008 6.0 . The 2020 on factory 34”+ tires has the best fuel mileage non towing, the fastest, holds higher speeds on 7 % grades with the same trailer. The 09 is best towing mpg by 1 mpg , shifts the least in tow haul mode although the 2020 in man 5 ( same top gear as 09 in tow/haul) isn’t very far behind. 09 is the most comfortable to drive towing with cruise on in hills . 2018 moves loads from dead stop with the least amount of throttle, has much smaller tires 245’s is second with mpg non towing. The l5p 2020 will win them all over but the 6.6 gas is better than my 09 in my opinion
They’d have to put 4:10 or lower in it with the 10 speed or it would hardly ever make it to 10th with the bigger tire combos. Rpms are low in 6th with the 3:73 . Probably could go up to 4:56 but that would have to high of a tow rating for someone to pick the diesel in a 2500 . The 6.6 gas got the power to do some serious towing with the 10 speed and lower gearing just don’t have the engine brake to stop it
What was it at 72
Just keep your half ton . If you’re that concerned with mileage you won’t be happy with any 3/4 on the market.
Carolina replied to Tuckertruck's topic in 6.6L Gas V8 & HD Transmission Powertrain (L8T/MYD)Are you sure you’re truck didn’t get flooded??
Lol . Here is my trip average, forgot to post it .
The shifting was noticeable but it wasn’t horrible . If I turned the radio on I would forget about it . It was landing barely above 3k . I’m fine with the mileage especially with gas at $1.80 a gallon . With the work it did it’s an improvement. I’m happy . I’ve never dropped below 8 in my LMM but neither has it hit 10 on this trip
Mine is silky smooth . The heads up display is awesome towing where you can keep your eyes on the road and not get a speeding ticket .Changing lanes with the technology package cameras is great too . I caught a car in the lane I didn’t see in the mirrors already towing my Travel Trailer
I just finished a 600 mile round trip from Sc thru NC and TN mountains towing 9130 pounds . Interstate grades were a 3 mile 6% , 1 mile 7 % , 6 mile 7% and a few 10% backroad grades . I can say I was amazed in the mountains. One thing I noticed is that it tows better on grades at speeds 65-75 vs trying to run 60 due to gear ratios in the transmission . With my setup at least with the 34+ tires . The first grade I hit running 61. It took about 2 miles to drop to 56 at 3200 rpms and I finally floored it to find it wouldn’t downshift further at first ( noticed the same with my 6.0’s ) so I double pumped it and it downshift to 5k , it immediately picked up speed and once it got to 61 5500 I backed off to try and hold the gear but it up shifted to 3500 and it continued to pick up speed no problem with the grade not letting up . It got to 71 and I just backed off more because speed limit was 65. I was less than half way into it on the initial climb and must have let it drop too much to recover . The 2 7% I hit at 66 mph and it carried the speed the entire way running 3700 rpm. On the way back I played around a little and drove 70-75 as the trucks stability wasn’t changed and wasn’t concerned about fuel as much . I hit one and made it downshift to 4K and it didn’t give a crap about the hill at that rpm . It accelerated me effortlessly past a car in the fast lane quick enough to get over before I got stuck behind a 35 mph semi . I pull those same grades 75% of the time when I rv and can’t tell you how many times that’s been but it put a spanking on my 09 duramax on those grades . I can only maintain 58 on the 2 longer ones nearly floored and if I ever tried to floor it to hold low 60’s it has always got to hot for me , transmission and motor . Ive never been able to get into the 70’s with it there . My 6.0‘S stay in the 4000-6000 rpm on those grades and usually drop to 56 floored with nothing left . Once I hit it running 75 and was able to keep 70 staying over 5000 the whole way up with my 6.0 and have tried to do it again and haven’t . But the 6.0’s never got even close to overheating and have had no mechanical issues . Downhill performance was a definite improvement over my 6.0 ‘s also . Not much difference from my duramax without an exhaust brake. When I slowed to 49 on a brake application and it downshifted the second time it eventually dropped to 44 on the 7% and I had to give it the gas to pick speed up before getting in the way . Fuel mileage was 7.8 -8.2 -9.5 . The only place where I can definitely say that my duramax was more pleasant was on the way back in the rolling hills running cruise it would go from 6th -5th after 2 mph drop then from 5th-4th at 4 mph drop . Afterwards it would climb back up to the speed I had it set at (70) . With my foot it was in 5th mostly with some drops to 4th when anticipated the hills and gave it enough pedal to downshift on purpose . I eventually selected manual 5 and set the cruise back and it would just drop 2 mph then recover . The hills were 5- 6% . My duramax tow mode automatically locks out 6th and will downshift on the same hills but it’s less noticeable because the nature of the diesel limited rpm range so 500 vs 1000 rpm increase . Overall i can clearly say it’s the most pleasurable tow I have had with any of my trucks ever . 50 miles into it I would have never thought it would be but after getting the feel for how it tows over a broad range I’m certain. In the backroads it was a cakewalk running 40-50 climbing much steeper grades . I know a l5p would do better but it still amazes me how it compared to my tuned LMM
So have you towed with one or you just watched the IKE pull and know everything about it now? You ever thought about the fleet perceptive ? The 6.0 is one of the most respected engines for HD service vehicles for capability , reliability and cost of ownership. The 6.6 has a 15-20 percent efficiency increase over the 6.0 . It has as much torque at barely over idle as it which translates into better towing and drive ability performance. Behind the wheel of one it feels very powerful and is a pleasure to tow with. Of course it doesn’t have a turbo like a diesel and if it did it would be challenge to drive . The 7.3 with the 4:30 gear won’t match the efficiency of the 6.0 much less the 6.6 . Most fleet buyers buy the gas version and historically consumers buy the diesel but that’s changing and all it takes is getting in one . The stigma of you gotta have a diesel is dying because it’s BS. Ford gave it there best shot . Gm is just getting started with this . They can add gear selections, transmissions and bring out a big block . What you see now with Ford is all it will be for years to come with the 7.3 . Either way none of it matters to me . I have a truck that I feel more confident in than in my Diesel with the same efficiency with lower cost fuel. It pulls my stuff without a sweat and when I upgrade my fleet vehicles I won’t think twice about getting the 6.6. No missed marks here I’m delighted with it .
The 6.6 is the base model just as Ford has a base model . Ford has 3 engine options. Gm has 2 . The GM big block capability is yet to be seen. The 6.6 is completely capable of its rating
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