We tend to have a narrow concept of fuel efficiency.... MPG is the standard and very subjective measurement, and it can be relatively meaningless number considering the different uses of vehicles. For example a car with 4 people on board making 20 mpg is equivalent of a single passenger vehicle making 80 mpg. Fuel burned for work done is what matters......not mileage. My pickup will do about 22 if I am conservative about how I drive. (full size extended cab 97 Chevy with automatic and 4.3 V6). It will average about 12 mpg pulling a trailer with about 3 tons of cargo, and that figure really reflects a far greater efficiency.. due to the work being done. A semi hauling 60,000 lbs of freight at 8 mpg is many times more efficient than a car hauling 200 lbs of meat making 40 mpg. 60 times as efficient to be exact!!
Now look at fuel consumption and examine other ways of viewing efficiency. A typical gas engine runs about 20% efficiency. The remainder of the fuel goes out as waste heat in the exhaust system and cooling system. 80% !!! Wow. And we all know that heat has no uses .... Think about that a bit............. Perhaps instead of striving to maximize fuel efficiency in terms of MPG, and banging our heads against a wall of diminishing returns...... we should be looking at waste heat, and how to capture and utilize it. I spend around $1000 a year in propane. I also burn about 1000 gallons of gas per year of which 80% is wasted! I could heat my home with those 800 gallons of wasted gas!! There are other uses for energy than just moving cars down the road!! This is about overall fuel efficiency, and that should include capturing and using wasted energy. If you could capture 20 of those 80 percentage points of wasted heat, you are operating at 40% efficiency instead of 20%....... The same as doubling your gas mileage!!!!
Agreed, MPG is not a complete look at efficiency; carpooling is another common example to demonstrate that issue.
3 tons of cargo in a trailer behind a 1997 half-ton pickup is not safe or legal.
It is very difficult to harvest all that waste heat but we often have discussions about ideas for it. Some of the issues include ancillary effects on upstream systems, cost to implement the waste energy recovery system, ways to store and use the energy, and space required for the system.
"3 tons of cargo in a trailer behind a 1997 half-ton pickup is not safe or legal."
Are you joking???
I've been hauling loads all my life, from 50,000 lbs payload on a semi on down. 3 tons behind a full size extended cab pickup that weighs in at 7500 lbs empty is trivial. I would have no hesitation hauling 5 tons if I didn't have 3.07:1 gearing and a 4L60E transmission, with an equalizer hitch or a gooseneck. My springs are not set up for that much on a trailer... the tongue weight is too much that far back. I modified the transmission to allow me to lock the torque converter up manually and leave it locked up while I'm pulling it.... this required me to build a simple box that fools the computer into believing things are "normal" so it won't throw error codes. I also disable the PWM valve so the computer couldn't slip the clutches.
The trailer is set up for a gross weight of about 11,000 lbs, but I don't have enough gears to handle on the steep grades we have in Montana. The trailer tires are good, the brakes work, an my ball is on the bumper (heavily reinforced), as well as the hitch being pretty long...... all giving me excellent control.
I've hauled as much as 3000 lbs right in the box of the pickup quite well and safely...... "half ton" is a designation, not a capacity. As an example, my GMC T6500 is what we would call a 2 ton. The actual rating is 24,000 lbs gross weight, and the rear axle with dual 19.5 tires is rated 18000 lbs capacity. It is common for so called "one ton" trucks to pull a gooseneck trailer with tandem duals rated for gross weight of 22000 lbs.
3 tons behind a full size extended cab pickup that weighs in at 7500 lbs empty is trivial.
A 1997 half-ton weighs 4000-5500 pounds empty. Also, you said 3 tons of cargo in a trailer, not 3 tons behind the truck. A trailer that can carry 3 tons weighs, at a bare minimum, another whole ton. A trailer whose loaded gross weight is 3 tons is nowhere near as bad but is likely to be outside the legal limit.
I would have no hesitation hauling 5 tons if I didn't have 3.07:1 gearing and a 4L60E transmission, with an equalizer hitch or a gooseneck. My springs are not set up for that much on a trailer... the tongue weight is too much that far back. I modified the transmission to allow me to lock the torque converter up manually and leave it locked up while I'm pulling it.... this required me to build a simple box that fools the computer into believing things are "normal" so it won't throw error codes. I also disable the PWM valve so the computer couldn't slip the clutches.
What does any of that (other than the springs and tongue weight) have to do with safety and legality? Safety is about braking and handling. Legality is about GCWR.
My 2002 GMC Sierra 1500 with the factory "HD trailering suspension" option (and more curb weight than a 1997 model) shows a tow rating of 8,000 pounds but that puts it well over the truck's GCWR in real life. In the past 10 years there has been a tow rating war where manufacturers have competed to increase tow ratings every year and a 2010 model may be legal for towing a trailer heavy enough for 3 tons of cargo.
In reality, a 6,000 pound trailer behind my truck feels heavy but is safe. I once towed one that I can only guess was 8,000 pounds and it was not safe for regular usage...that one time, all backroads, ok.
I've hauled as much as 3000 lbs right in the box of the pickup quite well and safely......
Yeah, it seems that these trucks are traditionally very underrated in their ability to haul cargo. 3,000 lbs in my 1500 was also fine.
"half ton" is a designation, not a capacity.
I know, and that's how I used it. Modern half ton trucks tend to be rated for almost a whole ton (mine's rated for 1800 pounds), and in reality can haul much more safely (but not legally).
The standard towing capacity is the maximum weight the Silverado can tow regularly. The 1997 Silverado half-ton trucks were broken down into two main body styles, the regular cab and extended cab. The regular cab had a standard towing capacity of 2,000 lbs. with two-wheel drive to 2,500 lbs. with four-wheel drive. The extended cab's standard towing was rated at 2,500 lbs. The two-wheel-drive extended cab with an 8-foot bed was rated at 2,000 lbs.
The maximum towing capacity is the most that the vehicle can tow safely. The regular cab models had a maximum towing capacity of 7,000 lbs. with four-wheel drive to 7,500 lbs. with two-wheel drive. The extended cab models -- in both two-wheel and four-wheel drive -- had a maximum towing capacity of 7,500 lbs.
Again, maximum towing capacity is not for regular use, and depends on the truck having a 150 pound driver and no cargo/accessories...it's GCWR minus OEM curb weight.
Also, check the rating and the law, you are probably required to use a weight-distributing hitch instead of the ball on the bumper.
[QUOTE=theholycow;158567]A 1997 half-ton weighs 4000-5500 pounds empty. Also, you said 3 tons of cargo in a trailer, not 3 tons behind the truck. A trailer that can carry 3 tons weighs, at a bare minimum, another whole ton. A trailer whose loaded gross weight is 3 tons is nowhere near as bad but is likely to be outside the legal limit.
I don't know where your weight figures come from, but mine is from the scale at the scrap yard where I'm weighed in loaded and weighed out empty. That of course includes two bodies, and the tools I carry behind the seat, a not insignificant weight, two spare tires, and typically 100 lbs of fuel.... total of perhaps as much as 900 lbs over factory empty weight..... deducting the extra weights mentioned, I'm still at least 1000 lbs above your maximum weight. It is a certified scale, and I do have scale tickets from when I'm hauling with just the pickup. It is an extended cab 2 door with a short box and two wheel drive, and a light engine and transmission........ It would be interesting to empty the pickup completely, and scale it with a full tank of gas which can be calculated... down at the rail yard scale. There definitely is no safety issue pulling trailer with it, nor does Montana law prevent me from legally pulling the loads I do.
An alternative fuel version of the Vortec 5700 V-8 is newly available, but to get it consumers must order a C2500 Regular Cab Longbed equipped with 8,600 lb. GVWR, a 3.73 rear axle ratio, and an automatic transmission.
So even a 2500 model doesn't necessarily come with a GVWR of 8,600; your truck that weighs "7500 lbs empty" must be at least a 2500 model or is severely overloaded.
I'd love to be proven wrong by photos of the GVWR/GCWR label showing that it's a 1500 and has a GVWR of 8500+ (that'd be your 7500 net weight plus a meager 1000 pounds of payload). It would be a freak truck and I'd love to hear what option packages (see the RPO codes on the label in your glovebox) made it happen.
A ship is even more efficient. The rail system as it exists is grossly inefficient for anything other than unit trains, and needs a major rethink. I have devised a system that would be massively larger, and would NOT start and stop, allowing cars to be cut in and out of a larger train on the go, as well as allowing freight containers to be moved easily and rapidly on and off a moving train. Eliminate the stops, and for both freight and passengers, rail quickly begins to make lots of sense. I even devised a system which would allow traffic in opposite directions on the same mainline by using "time windows", and sidings that did not require stopping and switching...Trains times to hit a "pass point" at the same time so they could blow by each other without ever slowing down. Parallel track segments with synchronized loader cars would allow freight and passengers to be embarked and debarked seamlessly from a train moving 50 mph or so......... There is a lot that could be done to improve rail. The bottle neck in public transportation is and has always been the need to stop at short intervals. Eliminate the starting and stopping of an entire load just to remove some freight or some passengers, and you not only save fuel, but save time. On light passenger rail, it appears that nobody has yet realized how simply this could be done... a "merge rail" with a loader car, which falls in behind the main train, and couples up briefly, allowing passengers to walk on and off. If you are getting off, you get on the loader for the station before the one you want off at, and the loaders advance one station with each cycle....... simple.... You get on the loader, and walk onto the main train...... walk from the main train onto the loader which then stops at the station.......the train never stops. In high stop density areas, the loader might be picking up passengers at half a dozen stops, and dropping them off at half a dozen stops, the main train just blasting along the full distance, so if you are going the full 100 miles for example, you never stop except during a brief period at each end of your route. It's dead simple..... a "no brainer", so why isn't it being done? This sort of thing would greatly improve the willingness to use public transportation. A properly designed shuttle bus, could even do neighborhood pickup / dropoff, and interface with light passenger rail with a bit of imagination.