found this VERY interesting article on DieselPlace web site. It does pertain to a 6.5L Silverado Trubo Diesel. (mine is a 1997 3/4 ton with 3.73 axle, ext cab, long box)
However, the author gives some great insight into those tow ratings and what I could REALLY tow. Based on this information about the 6.5L I figure I could pull, with some truck mods 10,000 GVWR and still be 3,000 below the 13,000 maximum. Having a GVWR of 10,000 doesn't mean you will load up to a 10,000 GVWR either.
- How much can the 6.5 (my truck) tow? Itís a diesel so it can pull anything, right?
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Thatís a bit of a loaded question. If you look at the ďFactoryĒ GM tow figures you may laugh your head off, or think thereís a misprint.(I certainly did)
For example, my (the author) 1997 1-Ton Dually 6.5
equipped truck was rated to tow a paltry 6000 pounds.
There are people here (and especially at the RV forums) who would suggest that you never (ever!) exceed these ďmagicalĒ figures, but we here at the Diesel Place look at it from a more realistic viewpoint - the 6.5 can tow a lot more then it was actually rated for.
Donít be stupid and think that youíre going to pull your friends 20,000# toy hauler fifth wheel, but donít be afraid by the low numbers in the manual, either - the realistic truth lies somewhere in the middle.
Done right, the 6.5 (Depending on your gear ratios and factory weight of your truck, crewcab LB versus single cab SB, etc) can tow heavy loads, but itís commonly accepted that for typical use about 13,000 LBS is the maximum
, and if you tow heavy with a 6.5 GAUGES ARE ESSENTIAL! Pyrometer, engine oil temperature and transmission temperature gauges! NO EXCEPTIONS!
Unless the previous owner installed these already youíll have to do so yourself. If youíre going to tow heavy with a 6.5, Budget it as part of your towing preparation.
A more free-flowing exhaust (discussed in the previous section) is also a wise idea to help control EGTís which are commonly an issue when heavy hauling. Needless to say, your cooling system must also be in tip-top condition otherwise you WILL (!!!) overheat towing with a 6.5.
Part of the reason 6.5 equipped trucks were rated to tow relatively low weights was the fact that heavy loads can easily drive the engine into temperature ranges where it can hurt itself. GM put extremely low rated tow limits on 6.5 equipped trucks because at those figures, even with a clueless driver at the wheel, the truck will typically manage just fine, even without all the gauges mentioned here that the truck isnít equipped with from the factory.
There are people that routinely pull fifth wheels weighing in the 16,000 Pound range with 6.5 equipped trucks (Equipped with 4.11 gearing, discussed below) and some that report towing equipment trailers weighing 18,000 or more, but gauges are critical as is your driving style - donít expect to race up grades on cruise control without paying any attention to things - you will have to work within the ability of the engine and ďTake your foot out of itĒ if the gauges indicate youíre working it too hard. Personally, I have hauled my 12,000 pound fifth wheel coast to coast, over many mountain passes, and up (and down) grades as high as 10% with my 6.5 and have been pleased with itís performance - read about my adventures at the link below if youíre interestedd.
Itís most important to again step back and realize that the 6.5 is NOT a Cummins nor a Duramax - it will not accelerate like them, it will not pull grades like them, and it probably won't stop as well either - so use your head!
The 6.5 is a much different engine from an architecture standpoint and was not designed (nor is it capable) to handle the heaviest trailers or loads out there, so go accordingly! In other words, donít buy an equipment float that weighs 25,000 pounds loaded and expect your 6.5 to pull it even if itís a 1-Ton dually - youíll have a bad experience and will probably end up breaking something.
There is a point where you have to ask yourself if what your'e trying to do is really safe, or even possible. If in question, ASK HERE - those with heavy hauling experience will be happy to offer our thoughts.
Lastly, your differential gear ratio will also drastically effect your towing ability. 6.5 equipped trucks with 3.42 ratios are very limited in what they can to tow, with the 3.73 ratio being better, (my truck)
but the 4.11 ratio being the best for towing. If you are planning to tow a heavy trailer, you want the 4.11 ratio, although for moderate or occasional towing the 3.73 ratio provides a good mix between fuel efficiency (when not towing) versus towing ability but will reduce your capacity by a few thousand pounds.
If you need help identifying your gear ratio, simply make a post here in the Diesel Place 6.5 forum, or search for previous posts on the subject using the ďSearchĒ function.
Of course, for towing heavy loads, ensuring your braking system (on both the truck and trailer) are working perfectly is essential.
Be smart, be wise, be careful.