Competition Launching in 4Wheel

[Sick Boy]

In April I ran my truck with the power max 3 and turned out a 16. 1 @88. 97 with a 60' time 2. 526. Since then I upgraded my box to the Comp adjustable and installed 6" stacks. Ran the truck again Friday night. This time I launched in 4 wheel drive since everyone said it makes times better. I shifted it back into 2 wheel between 2nd and 3rd-the truck actually takes a quick pause while doing this. With this ran, i turned out out worse times. with a 16. 474 @88. 55 60' time 2. 550



Does anyone know why I wouldn't be turning better times with this upgraded box? I figured I would do about a 15. 8 or 15. 9 with comp upgraded. Truck did not spin tires.

thanks

 

[E7mack96]

I just ran mine a couple weeks ago. I left it in 4 wheel drive all the way down the track, and switched to 2 wheel after the 1/4 mile. Just give it time to dis-engage before the hard turn to the left.



As for the launch, Do you have an auto, or a stick. I have a 6 speed, and found that I pretty much had to rev to about 2500 and dump the clutch, to keep the motor from bogging down.



The auto guys are building boost at the line, like 10-15 lbs i think, and launching hard.



I can't wait to bomb mine with the new Powermax CR.



I would think you would be gong faster than that too.

 

[Snow man]

DF2, do you have an auto or standard? What is your max boost,and egt's both before and after. your mph is low IMO,something is wrong. How about your fuel pressure? You should be hitting 93+mph with bd2's and a comp box. You should have picked up some low end/mid range power when you switched to the comp,but your max power should be about the same.

 

[Sick Boy]

E7mack and snowman,

I have an auto. I am building boost up to 10-11. Have no fuel pressure gauge. I think I might need a secondary lift pump Bullydog makes a big feul kit which helps the lift pump supply the injection pump It's about $250. 00 I am wondering if this will help.



I didn't know it was okay to leave it in 4 wheel all the way down the track-i heard to bump it out into two wheel in between 2nd and 3rd.

Also, you say my speeds are low but take in consideration that I have 4. 5" lift and 36" mud tires. Should my speed still be in the 90's??



Also, what is the powermax CR??

 

[HEMI®Dart]

Do you guys have the HD transfer case or the Standard one?

 

[HVAC]

I think you should leave with much more boost then 10/11. You want to run as much boost as possible to get the best 60' time. The beauty of 4x4 launches is there is no traction problem with leaving at high boost levels. Try 20 or 25 psi.



Also, leaving the xnsfer case in 4x all the way down the track has been done lots of times without problem.

 

[BillGotthelf]

Dieselfreak-get a fuel pressure gauge. How do you know what your lift pump is doing without one? Don't buy a booster pump without knowing whats going on. You should definatly be faster than you are. I am running 2wd and cannot leave without more than 3lbs of boost or my tires just spin. See my 99 sig below for more. Also most of the guys that launch in 4wd stay in 4wd all the way down the track and leave at 20 or more pounds of boost.

 

[Idaho CTD]

DF2,



Be careful leaving with too much boost if you dont have upgraded shafts in your transmission. Many a stock shaft has been broken above 15psi. Just a FYI

 

[Snow man]

Df2, I totally agree with Idaho CTD, I have broken more than one output shaft trying to launch above 20psi of boost. I wouldnt go above 15psi,unless you feel lucky. If you dont have a billet inputshaft/hub,that is even more reason to go easy out of the hole. Also leave t case in 4wd,since it wont disengage anyway under full throttle. Im guessing you dont know your fuel pressure,you need to get a guage on that sucker ASAP whenever your working the VP44 that hard. Is your auto built for the hp your at,what TC do you have. I stil think you should be able to hit 90+ if the trucks running right.

 

[KatDiesel]

Definatly keep it under 20psi, I launched in 4wd for many passes, I had up until last night kept it under 20psi. I was getting a lil too fired up racing a Supra and it snapped 1600rpm and 25psi. This was a cryoed shaft.

 

[KatDiesel]

#ad

 

[Jim Fulmer]

BAMB!!!!! Baby, yep heard about that one Eric and got to see one do the very same thing at the pulls in Muncie!



Jim

 

[Jetpilot]

Well there is a fix for the output shaft breakage.....



IE 1200 Output Shaft This will allow guys to leave the line and not worry about it breaking.

 

[KatDiesel]

Originally posted by Jetpilot

Well there is a fix for the output shaft breakage.....



IE 1200 Output Shaft This will allow guys to leave the line and not worry about it breaking.

I don't have the secret decoder ring to translate Doug... ... is this the billet shaft or the even bigger shaft from Bill via Opie?



Its on the list. but my list never seems to get any shorter for things to do on the truck

 

[Jetpilot]

Eric,



The IE 1200 Output Shaft is one of the models OPie is producing. If anyone is interested PM or email me and I will get you information.



Doug

 

[KLockliear]

You should try running the boxes back to back, launching the same way for a good comparison. They seem to be pretty close, looking at the MPH.



When racing our truck, I would launch in 4HI between 15-20psi, then shift out to 2HI just after the 1-2 shift. This disengages the TC even though the front hubs are still engaged.

 

[LoneRam]

Also, you say my speeds are low but take in consideration that I have 4. 5" lift and 36" mud tires. Should my speed still be in the 90's??

I don't know what gears you have, but I'm running 35x12. 50's with a similar set up and my best to date is 14. 0 with 1. 8X 60' times. I don't have the slip with me. I don't launch above 15 ever. Just don't feel like pulling the trans anymore for a while.



Tire Pressure?... . Just a thought.

 

[Kalaehina]

When launching in 4wh and then shifting to 2wh, would a 2wl kit like Bob V. s or BDs help out? Going down the stretch would you just use the switch instead? Would this be quicker and/or more convienient?

 

[KLockliear]

You would never use Low range at the drags.

 

[Kalaehina]

Sorry I meant using the 2wl switch in 4hi, you know how you can put it in 4hi but use the switch to disengage thus putting it back in 2hi range, could you do it this way?