Ok, obviously doing a 4x4 launch the engine will be under more of a load than 2 wheel. More load means more fuel which means more power, not to mention the traction issue. How much faster does a truck run in 4 wheel than 2 wheel? If any at all?

 

Most guys kick out of 4wd after hitting second gear. It is only for traction on the launch.

 

Like JD said, it is for traction. If you are not spinning in 2wd, there is not need to go 4wd, in fact, you will run a little slower in 4wd if you are not fighting launch traction issues.

 

thanks for the reply, just curious really. I know how much of a power gain I get when the torque converter locks in OD due to getting full lock up and more of a load, and fuel. So I was wondering if 4x4 would get more fuel. guess not though

 

No more fuel, but a boosted launch ie powerbraking it right before take off, will net a lot faster 1/4 mile time. Boosted launches is half the reason why an automatic transmission will run faster with less HP than a stick shift.

I get beat by stock automatics with a single chip all day long on the street if they do a boosted launch. If we are rolling 30 MPH, not many auto's with a single chip can hang with me!

If you do not have a billet input shaft, boosted launches are risky, but if you stay under 6 psi boost at launch, you should be ok.

Some guys launch at 20-30 psi boost with their fully built transmissions.

 

If you launch at 5 psi, you will probably boil the tires in 2wd, thus 4wd launch!

 

i launch in 4wd around 25-30 lbs boost when racin. I wouldnt do it without billet input and output shafts. Both will break easily with a good hookup

 

hahaha wow after reading this thread i switched the attitude monitor to show boost again and ive done a few 4wd launches at what looks like 10+ psi with my stock tranny, guess ill cut it back a bit.

 

Im familiar with boosted launches, they can weld clutches. Well, to be honest it's power braking with a 22 foot johnboat on the back that welds clutches, especially when overdrive kicks in. Dang dump truck driver beside me had to ask what she could do, and my dumb @$$ showed him. Needless to say I had to drop it off at the tranny shop before I got to go fishin, caught some nice red's, and tranny was under warranty other than paying for upgraded clutches seals and drop pan that I got for 150 bucks brand new. So I wasn't too upset, if it wasn't under warranty I would have cried like a baby. Thank god for Tim's 3 year unlimited HP, unlimited tow weight, unlimited mile warranty. Oh well, thats when you find a weak link. Anyway thanks for the input yall, just thinking a little to much yesterday i guess