Last trip to the track the best I could manage was a 1.97 60'. Current setup:

2003 rcsb 1500 sierra
Iron headed lq4/ 4l80e
gt45 69mm turbo 12.5psi at the time
old school harlan 2 step
ptc 3k torque converter, pushes to 4500 in boost, footbrakes to 2500ish
vacuum assisted booster
4.11s with 28x10.5x15 et drags on 15psi, clamped leafs

I was building 4-5psi on the 2 step at 2500rpms. Tried to raise the 2 step some more and it started pushing through the brakes. Even with the syty shuffle it does the same. What would be everyones next step? Will a hydroboost solve this or will I still have issues getting boost of the 2 step? Do my gears hurt me for building boost? I've thought about doing the sloppy transbrake as well(locking the trans in 3rd and letting it downshift on the line after boost is built.) Also, thought about nitrous or a transbrake. Although, thats more then I'd want to spend. I can look at my looks to see the base timing when I'm on the 2 step if anyone thinks timing would help it.

 

I had same kind of problem. I put spray(nitrous) on mine to help spool up. I later found that my waiste gate was missing the fire ring, which causing me to build boost too slow. fixed the fire ring on waiste gate and now it 60'. Just something to look into!

 

Do you pull any timing on the 2-step? I pull ALL of the timing out of it (-10 degrees) which kills the power so it doesn't push through the brakes..but still lets it bang through the turbo building boost. It will easily make 4-5 pounds at 2800 without even being close to pushing through the stock (drum) brakes. That's with a 3500 converter.

 

What exactly is the fire ring. I changed the springs here lately. I also would like to note that after a escapade last night, I cannot build more then 14lbs of boost with any spring, no muffler, or air filter. Boost leak on the hotside maybe?

No timing pulled at all on the 2 step. i figure it is running off my base timing which should be 8-13*. I always thought you wanted more timing to spool, but this concept has confused me for a bit.

 

fire ring goes in between the WG and your manifold flange. It sits in the base of the WG

 

What brand waste gate do you have?

 

Excellent quality china 60mm.

 

 

This is basically the same wastegate I have. Mine came with 4 springs which I have no idea what they are. Looks like the fire ring is built into the flange on mine?

 

Now that I think of it I may check my flex pipe in my crossover. A leak on my hotside would make sense for a lot of things. Im just using a regular flex pipe from the exhaust shop