We were recently asked if putting a larger engine in a Westy would enable it to tow more. Well, it depends on more than just your engine.
The topic of towing—and the decision of whether or not to tow a particular object of a particular weight behind a Vanagon—depends on several factors.
The first and most obvious is whether or not you have enough power to keep a safe speed. So, how much weight one can tow really depends on the terrain. Even with double the horsepower and torque, a Vanagon that is not towing anything would not be considered "over-powered." Any speed on severe grades is a challenge in a stock Vanagon, even without a trailer. With a stock engine, it is not wise to tow more than about 10% of the vehicle weight, about 400# max. With a GoWesty 2.2, you can up that to about 600#, with a 2.3 about 800#, about 1000# with a 2.45, and maybe 1200# with a 2.7 on just about any grade. On flat ground, you could probably double those figures. How big of a hill do you need to climb?
The second (and probably more important) factor is brakes. Any Vanagon owner that has driven down a long, steep grade in a loaded Vanagon has experienced fear. The larger GoWesty BIGGER-BRAKES are a vast improvement. We don't recommend towing anything with the stock Vanagon brakes. That is just asking for a disaster.
The third factor is stability. Stability in towing varies wildly depending on what is being towed and how its weight is distributed. A regular single-axle trailer improperly loaded can be an unwieldy beast. Even double-axle trailers can be spooky if not loaded properly. Proper loading of any trailer is typically considered to be when 10% of the total trailer (and its contents) weight is being applied on the trailer hitch ball. That in and of itself pretty much limits the amount one can expect to tow with a Vanagon, as the trailer hitch is probably good for about 250# max (that translates to 2500# trailer and contents total). Stability can be greatly improved with the addition of trailer brakes, which will help with the aforementioned second factor as well. Towing a vehicle with all four wheels on the ground or with a car dolly is inherently more stable because there is no tongue weight at all, and the four wheels on the ground are far apart (long wheel base). Towing a vehicle with a tow dolly that has brakes is probably the most easy and stable towing of all.
So, that was my long answer. My short answer: It is really up to the individual. Back about twenty five years ago, being the minimalist that I am, I purchased a 1982 VW Rabbit diesel pickup. It came time, in the course of building my business, that I needed to tow vehicles around the state. I decided to do it behind my little pickup. I replaced the original normally aspirated 1.6 liter 50HP/90 ft-lb diesel engine with a custom-built 1.9 liter 90HP/180 ft-lb intercooled turbo diesel engine. I replaced the front brakes with X-drilled Scirocco 16 valve brakes, and fitted it with an Audi 5000 master cylinder. I bought myself a tow dolly with hydraulically dampened steering and electric brakes. I towed vehicles all over the state of California behind that little truck for years without incident. You should have seen the heads spin when I would blast by folks in the slow lane, in a little black VW pickup, at 75 MPH, towing a VANAGON WESTY behind me! Don't get me wrong, it was no picnic. In fact, it took a level of concentration not unlike what is needed for the 24 hours of Le Mans. It was a white knuckler on many occasions, you can bet. But, I did it, it was legal, and I am alive to tell about it.
So, CAN you tow something behind your Vanagon, and if so, what and how heavy? Well, I know the vehicle can handle it if set up properly, and driven with respect, caution, and SHARP concentration. Now, can I tell you if you should do it? Well, I am not going to touch that with a ten foot trailer...