Competition launch

[lumberjack98]

I had a few questions about launching and such.

1)hold brake pedal apply throttle and let off pedal and hammer it?

2)how much boost to launch with I have some mods but no input shafts yet?

3)Egt mine climb fast is it a problem if only going 1/4 mile?

4)Egt if it gets to 1400 deg how long can it stay there before trouble

I have a boat and some rolling hills that will get it hot?

5)when running on the dyno i ran 4th gear (overdrive) and does the dyno take into account for the lower gear ratio (numerically) of the overdrive gear or should it be done in 3rd 1:1 ratio with the converter locked?



Sorry for the long post and battery of questions but i am a little green when it comes to diesel racing. thanks for your help.

 

[TGibbs]

a 1/4 mile isnt a big factor with high EGTs. Last time I raced, I launched at 10 punds of boost and hit pegged the 1600 degree gauge by the time I hit 2nd, though it was also 100+ degrees out.

 

[KingS]

I launch with 20lbs of boost in 4x4 when I run and I've seen truck run 1400 post turbo on the 1/4 and they are still fine and they run alot but let it cool down between runs

 

[lumberjack98]

thanks guys my pyro sensor is pre turbo . when you launch in 4wheel drive do you take it out of 4x4 after the first shift or do you leave it in the whole time? not sure if my stock input shaft will hold 20# of boost or if i should launch at 10# or 15# to be safe? (daily driver and mods have taken effect on wallet) tia

 

[fest3er]

I had a few questions about launching and such.

1)hold brake pedal apply throttle and let off pedal and hammer it?

2)how much boost to launch with I have some mods but no input shafts yet?

3)Egt mine climb fast is it a problem if only going 1/4 mile?

4)Egt if it gets to 1400 deg how long can it stay there before trouble

I have a boat and some rolling hills that will get it hot?

5)when running on the dyno i ran 4th gear (overdrive) and does the dyno take into account for the lower gear ratio (numerically) of the overdrive gear or should it be done in 3rd 1:1 ratio with the converter locked?



Sorry for the long post and battery of questions but i am a little green when it comes to diesel racing. thanks for your help.

Since you are new to drag racing, I'll suggest you ease into it; consistency (doing the *same* thing *every* time you launch) is more important than maximizing your raw torque. For bracket racing, you could probably be most consistent launching at idle.



1. Stand on brake, apply some throttle, and at the right time, release the brake instantly and quickly ease the go pedal to the floor. ('Quickly ease' means over a 1/2 second or so, not instantly jamming it to the floor. )



2. 10# boost is quite adequate, though you might also play with picking an RPM instead. Consider enough RPM to take up any slack in the driveline - keep it taut for the launch.



3. Unless you reach 1800-2200 degrees, I don't think EGT is much of a problem in a 1/4 mile at moderate power levels.



4. You can probably get away with 1200, pre-turbo, for a minute or three, and 1400 for maybe 30 seconds. Any longer, you should downshift - get more air flowing through the engine and let it work less. The longer you run the engine at extreme EGT, the shorter its life will be.



I'm sure die-hard, heads-up drag racers will tell me I'm full of it on a couple of my responses. But consider learning how to drag race to be like learning a new job: you'll do best if you learn to do it well before you try to do it fast. Look at TS Performance's Earl Talley. I doubt he got to be so deadly on the tree by launching BTTW all the time; I'll bet he learns how each vehicle works before he tries to minimize ET and maximize MPH. And as a bracket racer, he may not care much about ET and MPH; it may be that all he cares about is staging and launching the same way every time: being consistent.



Oh, and you should be able to leave it in 4WD the whole 1/2, so long as all four tires are the same size/make/model. More than likely, even if you shift out of 4WD, there'll be enough pressure on the driveline so that it won't disengage until you take your foot out of it anyway.

 

[DavidTD]

One thing I will add about boost at the tree.



Every set-up can be different. Stall speed of the converter and HP/TQ generated from the engine has a lot to do with how much boost you can launch with. Some set-ups allow 30+psi, others 10 psi. There is not a hard rule where shafts break.

 

[Graphic man]

keep in mind the harder you try and launch it the more chance of breaking parts,

i would start out slow and work your way up like fest3er said, do the same things all the time, bracket racing is all about consistency, you only need as much boost as it take to light the turbo, try it at 5 -8 psi your first few times, look at your 60' times on your slip of paper and you will soon learn the best rpm or boost to launch at.

do it in 4x4 all the way down the track, once you are through the traps at the other end then put it back in 2x4.



Scott

 

[CBrabec]

Is it really safe to run my truck in 4wd going 100mph or more down the track? Won't that hurt anything? Just wondering?

 

[Graphic man]

Is it really safe to run my truck in 4wd going 100mph or more down the track? Won't that hurt anything? Just wondering?

you are fine to run it in 4x4 at over 100mph, just take it out after the 1/4 mile, so you can turn and come back the return road.



you can try and run it in 2x4 but you wont be able to build boost and you will light up the rear tires, thats why you need to run it in 4x4.

 

[MCummings]

Is it really safe to run my truck in 4wd going 100mph or more down the track? Won't that hurt anything? Just wondering?

I thought you were drag racing?



Yes, it's bad for it. It would last 300,000 miles, but now, probably only 100,000miles.





Merrick

 

[CBrabec]

I thought you were drag racing?



Yes, it's bad for it. It would last 300,000 miles, but now, probably only 100,000miles.





Merrick

Ok you confused me? So is it safe or not? I'm wondering this for drag racing as well as racing on the street.

 

[MCummings]

Ok you confused me?

Are you asking me? I think I did confuse you.



Breaking is racing. Will your t-case break, or fail prematurely because of drag racing? Yes, of course. Anybody who says otherwise may be suffering from some cranial rectum inversion.



Drag racing is not for those who are worried about breaking parts. The last 3 passes that I have done down the track I blew my motor everytime. That was after 3-4 years of racing almost every sunday night.



Everything in your truck will fail prematurely because of the abuse you will do to your entire vehicle. From your seat cushion, to your brake pedal, your brake pads to your u-joints, and all the way to your input shaft, and transmission fluid.





Have fun! that's what it is really all about.





Merrick

 

[Luken]

Are you asking me? I think I did confuse you.



Breaking is racing. Will your t-case break, or fail prematurely because of drag racing? Yes, of course. Anybody who says otherwise may be suffering from some cranial rectum inversion.



Drag racing is not for those who are worried about breaking parts. The last 3 passes that I have done down the track I blew my motor everytime. That was after 3-4 years of racing almost every sunday night.



Everything in your truck will fail prematurely because of the abuse you will do to your entire vehicle. From your seat cushion, to your brake pedal, your brake pads to your u-joints, and all the way to your input shaft, and transmission fluid.





Have fun! that's what it is really all about.





Merrick

Well said... .

 

[CBrabec]

Are you asking me? I think I did confuse you.



Breaking is racing. Will your t-case break, or fail prematurely because of drag racing? Yes, of course. Anybody who says otherwise may be suffering from some cranial rectum inversion.



Drag racing is not for those who are worried about breaking parts. The last 3 passes that I have done down the track I blew my motor everytime. That was after 3-4 years of racing almost every sunday night.



Everything in your truck will fail prematurely because of the abuse you will do to your entire vehicle. From your seat cushion, to your brake pedal, your brake pads to your u-joints, and all the way to your input shaft, and transmission fluid.





Have fun! that's what it is really all about.





Merrick

You did say it well. My main reason for asking is that I like to race around town and every once in a while at the track. I have done 4wd boost launches but have taken it out of 4wd after hitting around 45-50 mph. I just have heard of people running down the drag strip in 4wd the whole way. I didn't think that was safe, but I'm still very new to all this. My truck isn't designed for the drag strip, just mostly fooling around town racing rice burners, fords & chevy's :-laf and occasionaly going to the drag strip. I figured if I take it out of 4wd around these speeds, I should be safe.

 

[MCummings]

I have done 4wd boost launches but have taken it out of 4wd after hitting around 45-50 mph. I just have heard of people running down the drag strip in 4wd the whole way. .

I bought a truck that had 100,000 miles, and about 75k of them was full 4wd passes down the track, and the t-case didn't show any wear, except for when the front u-joint broke, and cracked teh transfer case.



I think you'll be fine running all the way down the track in 4wd.



Don't run in 4wd daily driving though, just racing. Constantly running in 4wd will have your t-case split in two within the month.



Merrick

 

[Graphic man]

if you don't have a billit input or out put shaft, that will be the first to break,

and if you break a input shaft good chance you will do some big damage to the trans.



yes... . racing is breaking