I have the GMC 3/4 ton truck with the '6liter' engine (about 384). This engine is unable to tow my 25' trailer uphill at highway speeds, so I would imagine the 354 (???) would be less effective. If you meant 454, that is likely a whole different story. Also, engine is not the only factor in towing capacity, you also need the right gears, as well as transmission cooler, etc.
Hertig, please tell me more about your difficulty towing at highway speeds. I have a Chev 2500 HD with the same 6 L, 300 hp eng. & shopping around for a 5er that weighs up to 8300 lbs. How much does your Terry weigh? Do you pull it with full water tanks?
Hertig, please tell me more about your difficulty towing at highway speeds. I have a Chev 2500 HD with the same 6 L, 300 hp eng. & shopping around for a 5er that weighs up to 8300 lbs. How much does your Terry weigh? Do you pull it with full water tanks? I have the 4.10 gear ratio, auto. & tow pkg.
My Terry is rated at about 7200, dry weight is about 5200, I was towing it with water tank 1/3 full, so I would guess the weight to be in the 6000-6500 pound range. My truck (extended cab, long bed, 410 gears, towing package) gets about 12 MPG unloaded, around town. Pulling cross country (AZ to NY and back), I did not have any problems as long as the highway was level or downhill, cruise kept it right at the speed limit (usually 70 MPH). However, any up grade, the transmission would downshift, and usually the speed would drop down 5 to 10 MPH. I didn't go up any really steep grades (the worst was going west between Abilene and Albuquerque). At times during this stretch, I was limping along at 50 MPH and could not get it to go any faster. Neither transmission temperature or engine temp ever raised above normal. At low speed (20 MPH or so) I had no trouble up a short steep hill. I did not use the Tow/Haul mode, as the manual states that this is for when you are towing close to the truck limit and I was only at about 50%.
I haven't figured out the gas mileage exactly yet, but one relatively level stretch computed out to exactly 8.7 MPG, and an estimate between Abilene and Albuquerque was 6 MPG; possible, but suspect because the leg before that estimated out to 12 MPG.
The truck will probably do the job, just not always as quickly as one might prefer. I'm not looking forward to my first REAL up grade; I wonder if I would have been better off with the 8L engine...
Thanks, John. I'm not going to be in any hurry while pulling, so not too worried. But, I'll sure give priority to the lower weight 5ers I'm looking at. Guess I should have paid the extra 5 grand for the power stroke !
First, I would recommend that you should use Tow/Haul. I believe that the GM manual refers to total weight of truck and trailer, not just trailer weight relative to towing capacity. Second, because you are not using T/H, it sounds like the transmission is not downshifting when it needs to. Even with T/H engaged there are times when a manual downshift or applying more gas to force a downshift may be helpful to keep the engine power up. But overall, your towing results sound terrible given that you have the 6.0L and a 4.10 axle. Either the trailer brakes are dragging, the 6.0L is not running right or the 5th wheel is very un-aerodynamic.
I only have the 5.3L with a 3.73 axle. My 5th wheel is a 27.5ft Trail-lite (mid-profile) that is 5000lbs dry, 6550lbs GVWR. I am about 90% of my GCWR of 13000lbs. I have no problem towing to Cloudcroft, NM at 9000ft using 3rd gear (limited by speed limit more so than lack of power). And last fall, I completed 4500 miles (90% towing miles) to Canada and back to Texas and averaged 11.3 mpg. Mileage on the Interstate was about 12 mpg (65 mph, OD and rpm's under 2000) and worst mileage was 10.1 mpg on the TransCanada Highway with it's speed limit and steep grades.