Re: Tow Ratings Conundrum
And towing capacity is not just a factor of engine torque and horsepower. Other factors include strength of the frame (assuming there is one), strength of the driveline behind the engine (transmission/transfer case, driveshafts, pinion gears, axle housings, axle shafts, wheel bearings & assemblies), suspension components, etc.
Even when comparing two engines of equal torque and/or horsepower, you have to consider what the shapes of the torque and horsepower curves are, especially what minimum rpm is needed to generate sufficient torque to get the combined rig (tow & trailer) moving from a dead stop. For instance, some 1.8 liter motorcycle engines are now putting out well in excess of 200 hp...but they're doing at somthing like 13,000 rpm...and I certainly wouldn't want to lash one up to 4000 lb trailer and try to start up a steep hill from a dead stop.
And finally, every engineering team (and company) has their own standards regarding margins for errors and longevity when their systems are taxed to the maximum ratings on a sustained or repititive basis.
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