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137 Posts
Hi all, sorry so long, it wasn’t this long when I started writing…..
Wanted to make a post about my first towing experience with my 2017 Colorado Z71. Its stock with no tune or modifications (it’s still under GM warranty). I’ve had the Colorado for almost a month now. I bought it to replace my 300,000+ mile 1999 Suburban K2500 with the 6.5L diesel. I typically don’t tow long distances or on very hilly roads. I tow my 24’ long, 8’ wide enclosed race trailer to and from the track. With the dragster and equipment it weighs probably 5500 lbs but certainly less than 6000. I still need to do a better job of balancing the load as the Colorado receiver is 2” shorter than the Suburban. I’ve modified my Suburban with a tune and intercooler and it’s been maintained meticulously. Torque is about 500 ft/lbs, up from the stock 400.
Took the trailer for a 60-mile tow to the track (even though it’s closed cause of COVID-19). I wanted to see how it would tow on the highway and over the slight hills we have. I live at sea-level in NJ and the track is in the “mountains” of North Jersey. In reality the track is at about 750 above sea-level so not really much elevation compared to where many of you tow out west. It was rainy and wet so not the conditions I would really be towing in but wanted to test it out nonetheless. I clamped on my $25 FitSytems mirrors I got from Amazon, raised the hitch 1”, set the weight distribution chains to 3-links like I did with the Suburban and I was set to go. I did check that the trailer was level and it was within 1-degree, I forget forward or rearward. BTW, the mirrors worked well, no real noticeable vibration and I was able to see down the side of my 8’ wide trailer. If I were towing long distances I would definitely invest in a set or Boost mirrors but for the daily trips to the track I think these mirrors are just fine.
I was pleasantly surprised. Right off the bat I learned that I can’t give it a lot of pedal from a stop in the rain as I would spin the tires. I’m still getting used to the dead-pedal so I was giving it too much too early. Acceleration was surprisingly good! The Colorado I think accelerated better than my Suburban with the same amount of pedal. I think this is probably due to the flatter and wider torque curve and additional gearing of the 6-speed transmission. Up into 3rd gear was very pleasant. The suburban has 3.73 gears, 4% larger tires and a 4-speed 4L80 transmission, and it’s modified.
My trip took me about 40 miles on the highway and then the last 20 on state routes. On the highway I maintained 65 MPH and on the state routes I went 50 or 55MPH. On the highway there is about a 3% grade that is about 2.5 miles long. My suburban could easily make it up this hill and maintain speed but it would unlock the converter and drop into 3rd gear forcing RPM’s to 3000-3200 which for the 6.5TD is way out of its torque/HP range. The Colorado had no trouble maintaining 65 up this hill but it did drop into 4th and 3500RPM. With the Suburban I would usually make a run at the hill and get up to 70 MPH at the base and try to maintain the converter staying locked up which would drop me to 65 by the time I crested the hill. I think I’ll probably do something similar in the Colorado, probably put it into tow mode to drop it into 5th.
On that hill the EGT’s hit 1200 just as a crested the hill. While cruising on the highway with slight hills the EGT’s stayed in the 800-900 range for most of the tow. I was reading from bank 1, sensor 1 EGT which as far as I can tell is the hottest of all the factory sensors. Engine temps rose from 175 to 185, oil temps rose from 185 to 200 and trans temps rose from 185 to 200. On the backside of that hill the temps came back down into normal. Boost while cruising was around 15 psi and pulled 24 during the climb. Although I don’t know this truck as well as my suburban I assume things would have stayed lower if I had made a run at the hill at 70 in 5th gear similar to what I would do in my suburban. I was able to pass an 18 wheeler that was chugging and losing speed up the hill.
For the record I don’t like the exhaust brake at all! I think with 5500 in tow it’s generally just RPM but didn’t seem to slow much on downgrades. On the backside of the hill as I approached the exit trying to just use the exhaust brake it kept downshifting and I basically got scared when it started revving above 4000 RPM’s and didn’t feel like it was doing much. Maybe I’m old school but 4000 RPM in any diesel just feels wrong to me, especially if it’s not doing much. I switched it off and just used the brakes. I was not towing in tow mode because I wanted 6th gear on the flats which the truck had no trouble maintaining without hunting and holding about 1700 RPM.
On local state routes the truck liked 5th gear at 55, no downshifting as it was holding 1800. On slight downgrades would shift to 6th to about 1400-1500 rpm but would drop gear with slight incline and hold that on flats and inclines. When I was going 50MPH it didn’t like holding 5th gear and would unlock converter, 55 seems the sweet spot.
I had noticed the front was a little light and wanted to wander on the highway with the chains set to 3 links. 4 links was tight, much tighter than I ever remember in the suburban but the truck drove so much better and didn’t wander on the highway. Hence I know I need to raise the hitch at least another inch as I have too much tongue weight. Remember, it was one inch lower than I use to be on the suburban. I may also decide to move the 20 gallons of methanol I have in the front of the trailer to the rear, that should take 130 lbs from the very front of the trailer and move it behind the axles. Trailer has a generator on the nose, fuel, small compressor, small tool box, microwave and cabinets forward of the axles. The dragster’s engine is behind the axles.
My only gripe if I have one is that I only got 13.5 MPG, I was hoping for more. My suburban on the same tow would get 10.5 and I thought given the extra gearing, the engine being less than half the size and the truck weighing almost 2000 lbs less I would have seen at least 15. Who knows, maybe it raining had something to do with it……
Wanted to make a post about my first towing experience with my 2017 Colorado Z71. Its stock with no tune or modifications (it’s still under GM warranty). I’ve had the Colorado for almost a month now. I bought it to replace my 300,000+ mile 1999 Suburban K2500 with the 6.5L diesel. I typically don’t tow long distances or on very hilly roads. I tow my 24’ long, 8’ wide enclosed race trailer to and from the track. With the dragster and equipment it weighs probably 5500 lbs but certainly less than 6000. I still need to do a better job of balancing the load as the Colorado receiver is 2” shorter than the Suburban. I’ve modified my Suburban with a tune and intercooler and it’s been maintained meticulously. Torque is about 500 ft/lbs, up from the stock 400.
Took the trailer for a 60-mile tow to the track (even though it’s closed cause of COVID-19). I wanted to see how it would tow on the highway and over the slight hills we have. I live at sea-level in NJ and the track is in the “mountains” of North Jersey. In reality the track is at about 750 above sea-level so not really much elevation compared to where many of you tow out west. It was rainy and wet so not the conditions I would really be towing in but wanted to test it out nonetheless. I clamped on my $25 FitSytems mirrors I got from Amazon, raised the hitch 1”, set the weight distribution chains to 3-links like I did with the Suburban and I was set to go. I did check that the trailer was level and it was within 1-degree, I forget forward or rearward. BTW, the mirrors worked well, no real noticeable vibration and I was able to see down the side of my 8’ wide trailer. If I were towing long distances I would definitely invest in a set or Boost mirrors but for the daily trips to the track I think these mirrors are just fine.
I was pleasantly surprised. Right off the bat I learned that I can’t give it a lot of pedal from a stop in the rain as I would spin the tires. I’m still getting used to the dead-pedal so I was giving it too much too early. Acceleration was surprisingly good! The Colorado I think accelerated better than my Suburban with the same amount of pedal. I think this is probably due to the flatter and wider torque curve and additional gearing of the 6-speed transmission. Up into 3rd gear was very pleasant. The suburban has 3.73 gears, 4% larger tires and a 4-speed 4L80 transmission, and it’s modified.
My trip took me about 40 miles on the highway and then the last 20 on state routes. On the highway I maintained 65 MPH and on the state routes I went 50 or 55MPH. On the highway there is about a 3% grade that is about 2.5 miles long. My suburban could easily make it up this hill and maintain speed but it would unlock the converter and drop into 3rd gear forcing RPM’s to 3000-3200 which for the 6.5TD is way out of its torque/HP range. The Colorado had no trouble maintaining 65 up this hill but it did drop into 4th and 3500RPM. With the Suburban I would usually make a run at the hill and get up to 70 MPH at the base and try to maintain the converter staying locked up which would drop me to 65 by the time I crested the hill. I think I’ll probably do something similar in the Colorado, probably put it into tow mode to drop it into 5th.
On that hill the EGT’s hit 1200 just as a crested the hill. While cruising on the highway with slight hills the EGT’s stayed in the 800-900 range for most of the tow. I was reading from bank 1, sensor 1 EGT which as far as I can tell is the hottest of all the factory sensors. Engine temps rose from 175 to 185, oil temps rose from 185 to 200 and trans temps rose from 185 to 200. On the backside of that hill the temps came back down into normal. Boost while cruising was around 15 psi and pulled 24 during the climb. Although I don’t know this truck as well as my suburban I assume things would have stayed lower if I had made a run at the hill at 70 in 5th gear similar to what I would do in my suburban. I was able to pass an 18 wheeler that was chugging and losing speed up the hill.
For the record I don’t like the exhaust brake at all! I think with 5500 in tow it’s generally just RPM but didn’t seem to slow much on downgrades. On the backside of the hill as I approached the exit trying to just use the exhaust brake it kept downshifting and I basically got scared when it started revving above 4000 RPM’s and didn’t feel like it was doing much. Maybe I’m old school but 4000 RPM in any diesel just feels wrong to me, especially if it’s not doing much. I switched it off and just used the brakes. I was not towing in tow mode because I wanted 6th gear on the flats which the truck had no trouble maintaining without hunting and holding about 1700 RPM.
On local state routes the truck liked 5th gear at 55, no downshifting as it was holding 1800. On slight downgrades would shift to 6th to about 1400-1500 rpm but would drop gear with slight incline and hold that on flats and inclines. When I was going 50MPH it didn’t like holding 5th gear and would unlock converter, 55 seems the sweet spot.
I had noticed the front was a little light and wanted to wander on the highway with the chains set to 3 links. 4 links was tight, much tighter than I ever remember in the suburban but the truck drove so much better and didn’t wander on the highway. Hence I know I need to raise the hitch at least another inch as I have too much tongue weight. Remember, it was one inch lower than I use to be on the suburban. I may also decide to move the 20 gallons of methanol I have in the front of the trailer to the rear, that should take 130 lbs from the very front of the trailer and move it behind the axles. Trailer has a generator on the nose, fuel, small compressor, small tool box, microwave and cabinets forward of the axles. The dragster’s engine is behind the axles.
My only gripe if I have one is that I only got 13.5 MPG, I was hoping for more. My suburban on the same tow would get 10.5 and I thought given the extra gearing, the engine being less than half the size and the truck weighing almost 2000 lbs less I would have seen at least 15. Who knows, maybe it raining had something to do with it……
