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Ray Pickle

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  1. If the brakes are not larger that could possibly be a point of minor worry.
  2. I would guess the obvious- more payload- more tires- higher towing max capacity- more width and weight. If
  3. Without experiencing your truck's specific symptoms its hard to ascertain if it is normal drivetrain "slop". I will say that the length of driveline and rear diff setup will cause a minor clunk under certain downshift parameters. I notice it is most consistent slowing and turning as someone else has already mentioned.
  4. Engine rpm / lack thereof, due to tuning by Chevy, is darn near all the difference.
  5. I have towed that route and had no problem maintaining speed far above what TFL accomplished. Clearly the truck will perform much better than their representation. No one that knows anything about towing would allow their truck to lug like they did in their test. Understanding the desire to test uniformly, thus leaving the truck in drive, the ultra conservative tuning by GM caused the poor result. Another poster alluded to thermodynamic characteristics of small block being the reason for this tuning. My own experience indicates normal operating temps for coolant and trans temps ascending that grade at higher rpm. Further I see no significant differences in cooling capacity between the big three that would require the GM trucks to limit engine speed under those conditions more so than the competition. I would sure be interested in a more in depth reason for the tuning parameters GM has chosen to use in this truck. I don't see where a 10 speed would change the result much with the tuning parameters GM is presently operating this engine under.
  6. Minor point of clarification: it appears the old 6.l wasn't nearly as pronounced of an issue as the 6.6
  7. Iam not an engineer but have a little experience in the field of auto repair and basic understanding of thermodynamics, and would love to hear how Ford has managed this issue better. Further I have curiosity as to what has negatively impacted the new 6.6 vs the old 6.0 which apparently didnt suffer from this problem TFL tested a 2015 and it maintained 4 to 5k throughout duration of ascent other than the last mile where it lost rpm to 2900 before downshifting and then revs to the summit. Just rewatched that and they mentioned the programing issue. If it was trying to protect itself from being outside safe operating parameters the downshift is hard to explain- same as the new 6.6.
  8. If the calibrations of ecm are attempting to deny downshifts under the circumstances of TFL test I will stick with my comments on poor programming parameters. After rewatching the footage and seeing the truck downshift just prior to the peak of ascent after allowing engine to lug to approximately 2k "not good". I am convinced that poor programming is the issue. As another has posted and I agree- the cooling capacity of this engine platform is robust and at least the equal to both Ram and Ford . There is no mechanical reason this powertrain combo cannot deal with the Ike in its powerband- 4 to 5500 rpm under most circumstances. Do you have powertrain calibration data indicating that heat soak or other parameters are at play actively causing this programming need? If so do the numbers indeed indicate the 6.6 is poorer at heat dissipation than Ford and Ram? I am genuinely curious and not above learning something new, just based on my own experience and actual use I find it hard to believe.
  9. It will easily hold 3 to 4500 rpm up the ike with more weight than you describe. Further the engine/cooling system will be happier in that range than lugging it and beating the bearings out of it as a result.
  10. However to your intial comment- the engine cannot. Further the ecm is by not commanding the downshift is in fact defacto denying it. The programming is the issue- I have towed the "ike" more than once and in similiar weather variables to the test conditions along with warmer days and have never been denied a downshift. Surprisingly the truck would hold 2nd gear at redline if I desired on the steepest sections or slowly lose speed and rpm ascending in 3rd towing 12k 5vr. Trans temp would creap as you would expect if I beat it like that so I choose not to. But neither trans nor coolant temps went anywhere near the danger zone. I typically choose to tow it at a more drivetrain friendly 40 mph ish range.
  11. Where all 5k of miles using 700 gallons towing? If so , that indicates about 7.8 mpg! Thats seems to indicate some pretty aggressive/high speed towing habits for that weight or a high % of hilly terrain. If there is any non towing miles in that figure it is more perplexing. High rpm high speed towing will probably burn a little oil and may be normal. If that is not the case I would be concern about the relatively poor mileage and oil consumption.
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