Competition Boost at the line?

[BCarmicle]

What psi should I do my 4x4 launch in from the line when drag racing? Got a DTT billet input and intermediate shaft and will eventually install a billet output shaft.



Brandon

 

[KLockliear]

I used to leave at 15psi. I found no better 60's at higher boost levels.

 

[BCarmicle]

I've only did a 4x4 launch a couple of times in this truck and was looking at the rpms instead of the boost gauge for some reason. Left the line at 2000 rpms. Guy in the Ford Harley Davidson truck (5. 4 V8 Supercharged) didn't have a chance.



Brandon

 

[CUMINNTSTRKN]

keith is right. between 15 and 20psi is perfect. any more that 20psi and traction starts to become a issue.





jim

 

[csutton7]

c-strkn--glad to see ya postin--hope things are going well--chris

 

[StakeMan]

18 psi was the sweet spot for me. I have no idea what the rpm was since my tach is dead when in kill mode.

 

[CUMINNTSTRKN]

thanks chris, yeh things are getting back to normal.



jim

 

[Idaho CTD]

With a stock output shaft be careful going over 15psi. They tend to break much higher than that and some break lower. Once you get the billet output then I would leave around 22-25psi if you have a limit slip in the rear and can keep traction. I would air the back tires down to 30-35psi and the fronts to 35-40psi.

 

[BPonci]

I tried a launch with no boost in 4x4 with 35 mudders. Smoked the tires on the launch and in 3rd gear forgot to turn the water on. Ran a 14:33 man that was fun.

 

[BCarmicle]

Do you guys have any idea of what my 1/4 times would be with my current set-up and doing a 4x4 launch at 15 psi. I've got the 48RE with a DTT 91% TC and Race VB and everything else they offered except for the output shaft. The truck dynoed at 511/970, torque calculated by tractive effort, on TST 6/6 and Edge 4.





Brandon

 

[XcumminsX]

WHAT THE HELL... . The DD turbo is holding up to the tst on 6/6 with an edge on level 4!? What are your egts like.



From a 1/4 calculator that will get you a 13. 8

 

[BCarmicle]

My DD turbo is doing pretty good. The reason its holding up is because its wastegated at 40lbs. and I can hit that real fast. Going to use it a my small turbo in a custom set of twins. The reason these other turbos are blowing up is because they are being pushed past their max boost levels. EGT's were 1500 degrees on 6/6 without the Edge box on a dyno run. Forgot to look at egts when I stacked the boxes on the dyno.



Brandon

 

[Rhondasway]

Why'd you get the DTT works but not the billet output? Didn't they just start offering the billet intermediates, when the outputs have been available for some time... ?

Regardless, it's gonna break so just get it over with.

Launch depends on traction. Max I've been able to do is 20 lbs with last year's tires. I hear some guys can do 30+. If you spin at all , you'll lose time.



Oh, and welcome back Mr. Fuller! I think I'm ready for a rematch...

 

[CUMINNTSTRKN]

rotten



thanks, i will look forward to it.



jim

 

[BCarmicle]

Rhondasway,



I haven't installed the output shaft yet because I didn't know how much drag racing I would be doing, but its most likely in the near future. From what I've been told theres not too many intermediates out there, but i was lucky enough to get one. When I had the trans put in they said that is the biggest stock output shaft they had ever saw. So I am goin to wait and see what it can handle. Probably launch at 15 psi and see what happens.



Brandon

 

[Idaho CTD]

Originally posted by BCarmicle





I haven't installed the output shaft yet because I didn't know how much drag racing I would be doing, but its most likely in the near future.



Brandon [/B]

Man I've heard that before! Trust me it is as addicting as can be. Especially when your fast enough to smoke most/all the street driven "fast" cars. There is nothing like lining up against a ricer and by the end of the track you can see him way back there in your rear view mirror

 

[BCarmicle]

Going to a 1/8 track tommorow night to test the truck. Hope there is some of those "fast" street cars there. After talking with DTT I've decided to only leave the line at no more than 10 psi and kind of take it easy since I am running big tires and wheels. Most likely goin to get the output shaft before the big May 1st race.



Brandon