Okay so im new to this forum and really need some help for a project.
I have to design a caravan that is pulled by a vehicle (not a car, or tractor).
The main ones are quads and bikes.

Which quad has the most powerful engine to pull a small caravan (8 foot by 5 foot). It wont be too heavy. Everything will be as light as possible

Im looking for the best suited quad, and trying to find out exactly how much they can tow. Im guessing the engine size will be important.
Would anything else play a factor on choosing the quad? such as tyre size etc.

Really need as much help as possible, fast.
Thanks.

 

You are looking for big engine, low range transmission, 4wd and weight. Best bet would be a UTV not an ATV. Biggest and baddest of those should be the Can-Am Commander 1000. I think that their stock towing capacity is around 1,500#.

For ATV's look at the Polaris 850, Can-Am Outlander 800 or Artic Cat Thundercat 1000.

One weak link for all of these is that they have IRS rear suspensions - this causes them to squat with excessive tongue weight.

 

Welcome.
How much weight we talking total? 300lbs? 600lb? 1,500lbs? More?

 

You might consider a Polaris Sportsman X2 700 or 800 or the newer version X2 with the 850. All have rear loads rated at 400 lbs. so they don't squat as much as regular IRS quads. I've pulled an industrial sized woodchipper up a hill that our 2 4wd trucks (one with a rear locker) couldn't get enough traction to pull on the wet grass. The quad did it easily but I wouldn't recommend it for too long. It's not so much if a quad can get it going. Most 500cc and above with low ranges can get it going. It's more of a matter of stopping it with either extremely good engine braking or good brakes or both. If you stay within the manufacturer's recommendations with most machines you'll be okay. I'd also recommend whichever quad has 4 wheel disc brakes or something equivalent like Yamaha's rear wet brake system that they have on the Grizzly 700.

 

It's not so much engine size as it is gearing, I have a 500cc quad that I use to pull downed trees with, a 12' log 18" in diamiter being draged through creeks and the woods can be darn heavy. What you want to consider is tongue weight as you may need a SRA quad as the IRS quads tend to squat with a lot of wieght. You said it is gonna be 8' x 5' on wheels so you shoud be OK with any SRA 500cc or larger with a low range.

 

I would not recommend pulling anything too much heavier than the atv. If you go up any steep hills then the heavier load may pull you back down or if you go down any big hills then it can cause the atv to jack knife or push you down. I use to have an Arctic cat 300(280cc) atv and while at my friends he needed to move a piece of farm equipment so we decided to hook it to my 300. we'll we hooked it up and it made the bike squat BADLY, the tires looked as if it was going to blow. I put the bike in super low gear(it had high,low,and super low) and pulled it about 150 yards with ease. Infact it moved so easy i hardly had to give it any gas,kinda surprised me. Any ways,the farmer stopped by and asked how we moved it,and told him with the atv. His eyes got wide and his mouth dropped, and said,"that thing weighs 2 ton". After he said that i went to look at the atv and realized it had bent the frame. point is that any atv will pull more than what the manufacturer says,but whether you can stop or not is the problem.

 

These are really good points. I have a quad that is heavy, (Polaris has one of the stoutest frames on their ATVs), probably weighing in at 700 lbs. dry. I have come close to being pushed down a hill with a 4x4x3 trailer filled with wet freshcut logs. I had to stay on the brakes the whole time as it was just pushing the tires if I relied on the engine braking. If weight is really an issue I would recommend either a UTV like a Polaris Ranger or Kawasaki Mule or the Polaris Big Boss 6x6 800cc. It has 6 wheels and 6 wheel drive in a quad width sized machine. Just some random thoughts.