I was out doing some errands the other day and it was nice so I zipped home and grabbed the G-Tech and headed out to do a few runs. I had just installed my Magnaflow Catback and McGaughys 3/5 drop so I was curious. The runs felt different but the times were good so I was happy. After the third run I looked over and I was in 4 HI. I guess I needed it to get through some snow and forgot to take it out. I have never launched in 4X4 before so I did a couple of more runs in 2WD for comparison purposes. The truck launches very well in 4HI and it does not seem to be a problem just to set it and forget it. There is a lot less wheel spin and in my relatively stock truck it actually seems slower and less dramatic. Even my relatively stock truck seems to benefit from launching in 4HI. I am not sure if the difference will be as noticeable when it warms up a bit and there is less salt residue on the road and I get a little better traction in 2WD but I will see. Here are a few screenshots for you.

The Speed Graph shows how much faster the truck is in 4HI. The Main Run and Comparison 1 are 4HI and 2and 3 are 2WD. Probably about .25 to .3 faster.



The HP to TQ Graph shows that the G-Tech shows as high or higher figures when launching in 2WD. Not really sure why this is? The figures also seem quite low for some reason. Always have seemed low?


The Acceleration Gs Graph shows the the Gs at launch are much higher in 4HI than in 2WD. 2WD always shows about .5G while 4HI seems to show .65G. The 2WD launch in this graph seems to be about .05G lower than normal.

 

Nice thanks for posting that.Ive allways launched in 4hi and taken it to 120mph in in with no issues.It's cool to have comparison since mine weighs about the same and your hd.I need to get to a track sometime, in the spring and spray the hell out of it.

 

The G-tech measures net horse power, not BHP, so it's always going to be low.

 

i always race in 4WD at the track. in 2WD i am also .2 slower.

 

with a 3000 stall, i have no options but to use 4WD for launching.

i have a g-tech too. i even noticed different numbers when i chose between auto 4WD and 4hi. i can't remember which one gives me better ET's, 4hi or auto 4WD.

i think 4hi was quicker. more responsive off the line. auto 4WD gave some wheel hop at times, thus making me slower

 

so really 4hi wont be any slower than 2wd?

 

I generally trap 2 to 4 MPH faster than a similarly setup Duramax 4WD at the track. The 4WD truck generally has E.T. advantage, not speed. A strong 4WD launch can net some great 60' times.