Semi-Tractor "Tractor" pulls

I was wondering what engines they are using in those full sized semi tractor fire breathin dragons you see at some tractor pulls. What kind of engine building tricks do they use?

Talking about passing everyone going up that next mountain fully loaded!
Bet the fuel mileage is more like gallons per mile though.

 

Well, While I know that gearing is part of it, you know they are getting lots of Hp out of those engines. Knowing how much they get from gas burners in drags, running nitro, I wouldn't be surprised if they were getting 3k hp out of those diesels in the pulls.

The way the weight shifts on those sleds, no matter how much torque or Hp you have, sooner or later the traction gives up. The torque is so outrageous you can see sparks fly from the drive shaft hitting the frame as everything in the driveline twists and leans.

Driver skill is also what wins or looses those events, just like drags.

What they need is a contest for trucker skills like they have for lumberjacks. Set up a narrow slot that represents the only spot left in a crowded and tightly spaced truck stop and see who can back in with the fastest time without hitting anything! Maybe a log book juggling contest.