When to shift

[argve]

Ok from you more experienced types.

I will more than likely be running mine down the track in the very near future and my question is when should I shift?

Should I run the rpms out to 3k (redline) then shift or should I grab a new gear when she hit's 2500 rpm. If I shift at 3k my next rpm will be 2k after the shift. But if I shift at 2500 it will ring in at 1500, which I know from reading the graphs that Cummins supplies that 1600 is peak torque for the 6bt.

So which one is better? I know that by seat of the pants it feels pretty about the same (still plastered to the seat back). I know that if I shift at 2500 Man o man I'm a gear slinging fool, it just seems like I'm having to shift more often - but that could just be my mind set.

 

[Mike]

Are you pulling or drag racing?

 

[Ford_Forgotton]

If your sled pulling, many rules dont allow you to shift. Your supposed to pick a gear and stay in it. DOnt think it applies to automatics tho.

 

[Russ]

I think Travis will be drag racing. I would say shift at or near peak hp rpms. But then again I don't drag race :Sly

 

[argve]

Drag racing

 

[geonc]

Sled pullin' is more fun , not mention a more constant load on the drive train as opposed to trying to cut a decent tree and then yokin' the gears!

try 2nd gear/4 low, wait for the flag guy at the end to give ya the OK, just snug up the chain and then get the rpms up to 2700 { I launch at 3k } or so then bring the clutch in
STEADY......don't slip it too long....you will feel the truck start moving and your gut will tell you if you are doing it right then when the clutch is in, drop the hammer
and SMILE till you feel all but stopped- and you WILL feel when it's time to shove the clutch in.
No sense in trying to chatter the front axle for a few inches

 

[rubberfish]

Hey Travis, I'd try to shift before you hit the govenor, 2800 or so.
That'll set you up nice for the next hole. It worked well
for the 3:73 I have in the GM. You guys have 3:54 or something, right?
I have the 4GSK and I don't run to the end, I try for 3400 or so
and that puts me at 2400.
None of this is coming from a pro, just a guy goofing off at the strip

 

[JohnBoyToo]

Ya wanna try to stay at peak HP & torque as much as possible...
torque is the amount of twisting (work) it can do...
HP is how FAST it does that work...
http://auto.howstuffworks.com/horsepower1.htm

****************************
now,
with shifting a standard there are more compromises you have to make...
if u shift at peak torque, it will drop to lower than that in the next gear...

 

[Freightrain]

You want to shift at peak torque. But with the wide ratios of these trannies, you might have to stretch it some to keep it from falling too low after the shift. Seems you have it mostly figured out already. The only way is to try different rpm's and see if it slows down or picks up. I don't think you'll see a major difference either way.

 

[lukesdiesel]

Thanks for the Info..... I want to try a sledpull sometime myself