I went drag racing for the first time a couple weeks ago, and I used a 4WD boost launch at around 5 lbs, 15 lbs, then 20 lbs of boost. 20 lbs of boost was by far the best launch:

60'- 2.073
330'- 6.247
1/8th- 9.845 @ 68 mph
1000'- 12.981
1/4- 15.6 @ 83.8 mph

Once I hit about 60 mph in 4WD, the truck seems to fall flat on its face, but if I'm in 2WD it will pull hard until I let out of the throttle. Seems like something's off here. I know there are more moving parts, but I wouldn't think it would slow me down that much. I do have a leaky transfer case with a noticeable vibration noise from either the transfer case or the front differential. Any ideas?

TIA, Nathan

 

The front and rear tires generally don't turn at same speed. Since driveshafts are locked together, the tires are trying to spin at least one tire. Loss of power perhaps. Measure the distance each tire rolls in ONE revolution. I suspect there will be noticable differences.

 

Would that really slow me down that much? I really wonder what other drag racers notice when they're pulling down the track in 4WD, if they notice a huge difference like that. I'll get out and measure the distance each tire travels in one revolution probably tomorrow after work and get back to you.