A semi is a specialized system (with specialized sub-systems; brakes,
suspension, etc) designed for hauling huge loads. A Vanagon is not a semi
tractor, nor does it have anything close to 300 horse, not to mention 15
forward gears, ten tires, etc. I don't understand why people keep insisting
on the illogical comparisons between semis and Vanagons. It's like comparing
a kid's toy model rocket with a Nasa booster; yeah, they're both rockets,
but so what?

As far as the formula below goes, I took its application to be a simple
dead-weight trailer or vehicle that was not assisting the tow vehicle in any
way (i.e. brakes). Assigning the number 35 to the formula is probably
shorthand for a more complicated formula; horsepower relates to torque,
which relates (in design) to the capabilities of the frame, braking system,
etc. in the common American production vehicle. In other words, a 'rule of
thumb'.

There's no way it's "all about torque", as in 'Never mind the speed, brakes,
suspension or condition of the vehicle, we've got tons o' torque!" I don't
buy it.
I learned to drive on a late '40s Ford farm tractor (tons o' torque), but I
wouldn't use one to take my travel trailer up into the mountains with,
unless I was planning to camp in it when I got there next year.

Cya,
Robert

----- Original Message -----
From: "Ryan Press" <ryan@PRESSLAB.US>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, June 23, 2004 2:05 PM
Subject: Re: Towing a Vanagon with a Vanagon?

> On Jun 23, 2004, at 4:12 PM, Robert Fisher wrote:
> >
> >     "The weight of the trailer is the most important factor. A good
> > weight-to-horsepower ratio is about 35:1, 35 lbs. of Gross Combined
> > Weight
> > (GCW) for every horsepower your engine develops. Multiply the engine's
> > rated
> > horsepower by 35 and subtract the weight of the vehicle passengers and
> > luggage. The number remaining is the approximate ideal maximum weight
> > you
> > should tow, although a numerically higher axle ratio can help
> > compensate for
> > heavier weight."
>
>
> Semi tractor trailer trucks weigh up to 80,000 lbs and have about 300 hp..
>  A ratio of 267:1!  It's all about torque, not horsepower, when towing
> something heavy.
>
> Ryan